Recent uci_eng_cee items

Characterizing wildfire behavior with ECOSTRESS land surface temperature across four California case studies

Wed, 3 Jun 2026 00:00:00 +0000

Since 2000, wildfires in the western United States have increased in both frequency and intensity due to hydro-meteorological shifts, prolonged drought, and expanded human activity. Although geostationary systems enable rapid detection and moderate-resolution sensors offer broad coverage, a gap persists for high-spatial-resolution thermal observations that can assess fine-scale fire behavior. The ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS) provides 70-meter land surface temperature (LST) observations with 1–5 days average revisit intervals, providing enhanced spatial detail for active-fire analysis. In this study, we evaluate the capability of ECOSTRESS Level 2 LST data, which uses 5 thermal bands, to characterize wildfire behavior across four California fires: Carr (2018), Kincade (2019), August Complex (2020), and Dixie (2021). We developed a consistent framework to identify hotspots (LST ≥ 60 ° C ), estimate a satellite-derived rate-of-spread...

An integrated transportation-power system model for a decarbonizing world

Sat, 11 Apr 2026 00:00:00 +0000

Rising demand for electricity from electric vehicles (EVs) will require new paradigms to guarantee reliable and low-cost electricity. This study couples an agent-based travel demand simulator and an electricity grid model to assess the economic costs of supplying power to meet EVs' added demand across the Chicago region. Results suggest that shifting from personal EVs to a fleet of shared, fully-automated all-electric vehicles (SAEVs) could lower per-mile emissions, congestion, and embodied vehicle and charging infrastructure emissions. The results should compel policymakers to shift the cost of providing power onto commercial customers, like electric ride-hail fleets, through price-indexed electricity prices, which can shift charging to off-peak periods or away from resource-scarce hours.

Innovation in environmental engineering for community-engaged research

Thu, 9 Apr 2026 00:00:00 +0000

Innovation in environmental engineering for community-engaged research

Classifying energy insecurity among households with medical devices through latent class analysis

Wed, 8 Apr 2026 00:00:00 +0000

Abstract: The growing prevalence of electricity-dependent durable medical equipment (EDME) in homes—such as oxygen concentrators, infusion pumps, and nebulizers—may widen health disparities. As climate change increasingly challenges electric grid reliability, understanding which EDME-dependent persons (EDPs) are most vulnerable to power outages becomes critical in addressing both health equity and climate resilience. Using data from 2,612 households in the 2020 Residential Energy Consumption Survey, we applied latent class analysis to identify distinct vulnerability profiles among EDPs. We identified four classes, with two experiencing energy insecurity but with different power outage preparedness probabilities and sociodemographic profiles. The most resilient yet energy-insecure class (20% of EDPs) consists primarily of homeowners with some alternative power sources (e.g., backup generators and solar panels). These findings suggest that interventions for homeowners...

The Role of Canopy Turbulence in Wildland Fire Behavior

Wed, 4 Mar 2026 00:00:00 +0000

Characterizing the physical and dynamic meteorology of wildland fires has obvious socioeconomic importance and is necessary to develop not only firefighting but also mitigation strategies such as prescribed burns and effective fuel management practices such as forest thinning. However, despite significant progress over a century, there are shortcomings in our understanding of the physical processes governing wildland fire behavior. Although some research progress has been made in understanding how fires spread on grasslands, several aspects of fire behavior within the forest canopy environment are still not well-understood. This review is an attempt to organize the fluid mechanics of the mass, momentum, and energy transfer during wildland fire events through the lens of vegetation canopy turbulence. The structure, organization, and progress of the flame front and the buoyant plume through the canopy are shown to be intricately related to the coherent structures associated with...

Transboundary water conflicts, cooperation, and pathways forward

Wed, 25 Feb 2026 00:00:00 +0000

Transboundary water conflicts, cooperation, and pathways forward

Beirut Air Pollution and Cleanup

Fri, 30 Jan 2026 00:00:00 +0000

The 2020 Beirut Port explosion released massive quantities of nitrogen oxides and particulate matter, creating an acute air quality crisis. While PM10 levels have largely returned to baseline, PM2.5 concentrations remain elevated at approximately three times acceptable cancer risk thresholds, continuing to threaten public health. A team of undergraduate students (Ethan Cheng, Justin Dawn, Sienna Hosseinbukus, Sarah Husain, and Venezia Mejia) from CEE60, taught by Professor Shakira Hobbs, developed a community-focused response strategy addressing ongoing air quality impacts. The proposed intervention employs decentralized mitigation through green roofs with locally adapted vegetation (Asteraceae, Iridaceae, Primulaceae, and Sedum), mobile HEPA filtration units, and low-cost particulate sensors in key community buildings. An Arabic-language social media campaign with Arabic & English subtitles was created to communicate health risks and promote adoption of these accessible interventi...

Measuring electric vehicle owners’ willingness to participate in smart charging programs

Wed, 14 Jan 2026 00:00:00 +0000

As power systems transition to renewable energy, integrating battery electric vehicles (BEVs) into grid operations presents new opportunities and challenges for managing electricity demand and the associated environmental impacts from BEV charging. This study examines two grid-integration strategies: supplier-managed charging (SMC), which gives utilities control over charging timing, and vehicle-to-grid (V2G), which transforms BEVs into distributed energy storage resources. Using a discrete choice experiment with 1,356 current BEV owners, we quantify how program attributes influence enrollment decisions. Using multinomial logit models, results suggest that SMC participants predominantly value operational flexibility and recurring payments while V2G participants prefer monetary incentives, indicating a willingness to provide grid services for compensation. Through simulation analysis, we identify program ‘attribute equivalencies’ that quantify changes needed in attributes to achieve...

An entropy-based multi-criteria approach for intensity measure selection in seismic resilience of structures

Wed, 14 Jan 2026 00:00:00 +0000

Seismic resilience (SR) has emerged as a critical focus in earthquake engineering to evaluate the ability of structures to endure, recover from, and adapt to seismic events. This study presents an entropy-based multi-criteria approach for selecting optimal intensity measures (IMs) to assess SR of structures. Eight representative IMs, derived from time histories and response spectrum are evaluated. Incremental dynamic analysis is conducted on a reinforced concrete structure, using engineering demand parameters such as the maximum inter-story drift and floor acceleration to generate fragility curves via a probabilistic seismic demand model. The optimal IMs are identified through a multi-criteria decision-making process, with scores calculated using the entropy weight method to incorporate factors such as efficiency, proficiency, and uncertainty based on information entropy. An effective SR framework is derived from fragility results. The findings indicate that peak ground velocity...

Multi-ignition fire complexes drive extreme fire years and impacts

Tue, 6 Jan 2026 00:00:00 +0000

Climate change is intensifying fire behavior, with the largest and fastest-spreading fires causing the greatest impacts on people and ecosystems. Yet the mechanisms driving variability and trends in large fires remain poorly understood. Using 12-hour satellite-derived fire tracking data from 2012 to 2023, we show that the merging of separate ignitions into multi-ignition complexes is a key process amplifying fire size and destructive potential across temperate and boreal ecoregions. Multi-ignition fires account for 31% of the burned area in California and 59% in the Arctic-boreal domain, spread faster and persist longer than single-ignition fires, and disproportionately contribute to extreme fire years in California, Canada, and Siberia. They also generate stronger atmospheric feedbacks, produce more pyrocumulonimbus events, and strain firefighting capacity by dispersing suppression resources. Recognizing and accounting for fire-merging dynamics are critical for improving wildfire...

Atmospheric Feedbacks Reverse the Sensitivity of Modeled Photosynthesis to Stomatal Function

Wed, 17 Dec 2025 00:00:00 +0000

Abstract Stomata mediate fluxes of carbon and water between terrestrial plants and the atmosphere. These fluxes are governed by stomatal function and can be modulated in many Earth system models by an empirical parameter within the calculation of stomatal conductance, the stomatal slope . Intuitively, represents the marginal water cost of carbon, relating it to the emergent plant property of water use efficiency. Observations show that can range widely across and within plant types in varying environments, and this distribution of is not captured within Earth system models which represent each plant type with a single value. Here we examine how influences photosynthesis using coupled Earth system model simulations by perturbing to observed and percentiles for each plant type. We find that high reduces photosynthesis nearly everywhere, while low has regionally dependent responses. Under fixed atmospheric conditions, low increases photosynthesis in the Amazon and central North America...

Structural Behavior and Design of Recycled LDPE-FRP Hybrid Beams for Bridge Collision Protection

Fri, 7 Nov 2025 00:00:00 +0000

Structural Behavior and Design of Recycled LDPE-FRP Hybrid Beams for Bridge Collision Protection

Quantifying the effect of temperature on belite hydration kinetics through quasi in situ XRD

Thu, 9 Oct 2025 00:00:00 +0000

Belite-rich cement is a promising low-carbon material, yet the limited hydraulic reactivity of its primary component, dicalcium silicate ( β -Ca2SiO4), still poses a challenge. This study introduces a new approach to examining the reaction kinetics and acceleration strategies for low-reactivity materials like β -Ca2SiO4 using quasi in situ X-ray diffraction (XRD). By simultaneously analyzing pre-cured and fresh samples, the method reduces measurement time at the expense of lowering temporal resolution. Applying this technique to hydrating β -Ca2SiO4 pastes from 21 to 80 °C provides insight into the underlying temperature-dependent dissolution process and its apparent activation energy (AAE). The estimated AAE of 49 ± 3 kJ/mol aligns with existing data and supports the view that the rate-limiting step of belite hydration may change based on the physical properties of the material. By offering phase-specific and time-resolved data, this method serves as a useful tool in devising...

Water and climate: Recognize anthropogenic drought

Wed, 24 Sep 2025 00:00:00 +0000

California's current extreme drought must be a lesson for managing water in a warmer, more densely populated world, say Amir AghaKouchak and colleagues.

Historical changes in overtopping probability of dams in the United States

Mon, 4 Aug 2025 00:00:00 +0000

With concerns about aging dams and nonstationary changes in hydrologic extremes (e.g., flooding), questions arise about whether existing dams may be at risk of failure and pose threats to society. Here, we analyzed 33 dams across the United States to investigate temporal trends in dam overtopping probabilities of annual maximum dam water levels. These dams were selected because of the availability of public domain long-term time series of uncontrolled water levels (50 years or longer). We applied updated stationary frequency analyses using generalized extreme value distributions on 30-year rolling periods from 1973 to 2022. The results revealed an overall increasing trend in the number of dams exhibiting critical overtopping probabilities (i.e., low, moderate and high) alongside a decline in the number of non-critical overtopping probabilities (i.e., very low) over time. This approach uncovered overtopping probabilities that traditional analyses based solely on dam water...

Evaluating options for balancing the water-electricity nexus in California: Part 1-securingwater availability

Wed, 30 Jul 2025 00:00:00 +0000

The technical potential and effectiveness of different water supply options for securing water availability in a large-scale, interconnected water supply system under historical and climate-change augmented inflow and demand conditions were compared. Part 1 of the study focused on determining the scale of the options required to secure water availability and compared the effectiveness of different options. A spatially and temporally resolved model of California'smajor surface reservoirs was developed, and its sensitivity to urban water conservation, desalination, and water reuse was examined. Potential capacities of the different options were determined. Under historical (baseline) hydrology conditions, many individual options were found to be capable of securing water availability alone. Under climate change augment conditions, a portfolio approach was necessary. The water savings from many individual options other than desalination were insufficient in the latter, however, relying...

Evaluating options for balancing the water-electricity nexus in California: Part 2-greenhouse gas and renewable energy utilization impacts

Wed, 30 Jul 2025 00:00:00 +0000

A study was conducted to compare the technical potential and effectiveness of differentwater supply options for securing water availability in a large-scale, interconnected water supply system under historical and climatechange augmented inflow and demand conditions. Part 2 of the study focused on determining the greenhouse gas and renewable energy utilization impacts of different pathways to stabilize major surface reservoir levels. Using a detailed electric grid model and taking into account impacts on the operation of the water supply infrastructure, the greenhouse gas emissions and effect on overall grid renewable penetration level was calculated for each water supply option portfolio that successfully secured water availability from Part 1. The effects on the energy signature ofwater supply infrastructurewere found to be just as important as that of the fundamental processes for each option. Under historical (baseline) conditions, many option portfolios were capable of securing...

From yards to cities: a simple and generalizable probabilistic framework for upscaling outdoor water conservation behavior

Wed, 30 Jul 2025 00:00:00 +0000

Outdoor watering of lawns accounts for about half of single-family residential potable water demand in the arid southwest United States. Consequently, many water utilities in the region offer customers cash rebates to replace lawns with drought tolerant landscaping. Here we present a parcel-scale analysis of water savings achieved by a 'cash-for-grass' program offered to 60 000 homes in Southern California. The probability a resident will participate in the program, and the lawn area they replace with drought tolerant landscaping, both increase with a home's outdoor area. The participation probability is also higher if a home is occupied by its owner. From these results we derive and test a simple and generalizable probabilistic framework for upscaling water conservation behavior at the parcel-scale to overall water savings at the city-or water provider-scale, accounting for the probability distribution of parcel outdoor areas across a utility's service area, climate, cultural...

Carbon mineralization pathways in interfacial adsorbed water nanofilms

Thu, 17 Jul 2025 00:00:00 +0000

Abstract: Carbon mineralization in humidified carbon dioxide offers a promising route to mitigate anthropogenic emissions in a world stressed by water security. Despite its technological importance, our understanding of carbonation in water-poor environments lags, as traditional dissolution-precipitation pathways struggle to explain the adsorbed water nanofilm-mediated reactivity. Here, we utilize in operando X-ray diffraction (XRD) and advanced molecular simulations to investigate nanoconfined reactions driving forsterite carbonation, the magnesium-rich olivine. By examining magnesium ion dissolution and transport in atomistic simulations of the forsterite-water-carbon dioxide interface and comparing these with the in operando XRD activation energies, we identify both processes as rate-limiting at saturation. Our simulations reveal a mechanistic view of interfacial carbonation, where dissolution and precipitation are mediated by anomalous quasi two-dimensional diffusion....

Engineered nanomaterials for water treatment

Tue, 8 Jul 2025 00:00:00 +0000

The pressing need for advanced, yet cost-effective water treatment has led to the development of a wide range of engineered nanomaterials (ENMs), from carbon-based to metal and metal oxide nanomaterials, and including novel structures such as metal organic frameworks (MOFs) and covalent organic frameworks (COFs). ENMs have been developed to treat conventional water pollutants as well as emerging contaminants, and address new challenges. In this article we provide an overview of the current literature on a wide range of ENMs as well as several major classes of water contaminants.

Aging of Copper Nanoparticles in the Marine Environment Regulates Toxicity for a Coastal Phytoplankton Species

Tue, 8 Jul 2025 00:00:00 +0000

Environmental conditions in aquatic ecosystems transform toxic chemicals over time, influencing their bioavailability and toxicity. Using an environmentally relevant methodology, we tested how exposure to seawater for 1-15 weeks influenced the accumulation and toxicity of copper nanoparticles (nano-Cu) in a marine phytoplankton species. Nano-Cu rapidly agglomerated in seawater and then decreased in size due to Cu dissolution. Dissolution rates declined during weeks 1-4 and remained low until 15 weeks, when the large agglomerates that had formed began to rapidly dissolve again. Marine phytoplankton species were exposed for 5-day periods to nano-Cu aged from 1 to 15 weeks at concentrations from 0.01 to 20 ppm. Toxicity to phytoplankton, measured as change in population growth rate, decreased significantly with particle aging from 0 to 4 weeks but increased substantially in the 15-week treatment due apparently to elevated Cu dissolution of reagglomerated particles. Results indicate...

Satellite-based vertical land motion for infrastructure monitoring: a prototype roadmap in Greater Houston, Texas

Wed, 4 Jun 2025 00:00:00 +0000

Coastal regions are critical hubs for industries reliant on transport and storage. However, vital infrastructure including above-ground storage tanks (ASTs), which store hazardous materials, is vulnerable to flooding and often exacerbated by subsidence (negative vertical land motion; VLM). The U.S. Environmental Protection Agency plays a key role in mitigating risks from ASTs. Satellite remote sensing provides a powerful tool to assess hazards and inform decision-making. Here, we present a roadmap for integrating remotely-sensed observations into decision-making frameworks. Using NASA observational products for end-users from remote sensing analysis (OPERA) VLM products derived from Sentinel-1, we map VLM at ~ 30 m resolution across Greater Houston–Galveston. Our analysis reveals widespread, spatially varying subsidence. We determine where VLM trends were linear from 2016 to 2023 and extrapolate them to estimate future VLM. Combining sea-level rise (SLR) scenarios with VLM...

A gradient-boosted tree framework to model the ice thickness of the world's glaciers (IceBoost v1.1)

Wed, 4 Jun 2025 00:00:00 +0000

Knowledge of glacier ice volumes is crucial for constraining future sea level potential, evaluating freshwater resources, and assessing impacts on societies, from regional to global. Motivated by the disparity in existing ice volume estimates, we present IceBoost, a global machine learning framework trained to predict ice thickness at arbitrary coordinates, thereby enabling the generation of spatially distributed thickness maps for individual glaciers. IceBoost is an ensemble of two gradient-boosted trees trained with 3.7 million globally available ice thickness measurements and an array of 39 numerical features. The model error is similar to those of existing models outside polar regions and is up to 30 %-40 % lower at high latitudes. Providing supervision by exposing the model to available glacier thickness measurements reduces the error by a factor of up to 2 to 3. A feature-ranking analysis reveals that geodetic data are the most informative variables, while ice velocity can...

Peer-to-peer residential charger sharing: Exploring public perceptions in California

Fri, 16 May 2025 00:00:00 +0000

Peer-to-peer residential charger sharing: Exploring public perceptions in California

Recent fire history enhances semi-arid conifer forest drought resistance

Mon, 5 May 2025 00:00:00 +0000

Climate change is amplifying both wildfire burned area and severity, as well as incidents of drought-induced tree mortality (dieback). Direct effects from climate change amplify wildfires and episodes of drought-induced dieback have well-known impacts on forest's ability to regulate climate, provide water, and store carbon. Less understood are how past disturbances produce interaction effects that can change subsequent disturbance occurrence and intensity, with implications for management decisions that can promote forest resistance and resilience. We constructed two parallel forest chrono-sequences by combining a geospatial database of historical fire with satellite and airborne observations of forests in the Sierra Nevada of California to assess the impact of fire history on vegetation recovery, water use (evapotranspiration), and drought-induced forest dieback. We used these data sets to assess two research questions: (1.) Does fire history amplify or reduce drought-dieback...

Rising forest exposure and fire severity from climate warming amplify tree cover losses from wildfire in California

Mon, 5 May 2025 00:00:00 +0000

Warmer temperatures and severe drought are driving increases in wildfire activity in the western United States, threatening forest ecosystems. However, identifying the influence of fire severity on tree cover loss (TCL) is challenging using commonly used categorical metrics. In this study, we quantify regional trends in wildfire-driven TCL as the product of annual burned area, average forest exposure (pre-fire tree cover), and average fire severity (relative loss of tree cover). We quantified these trends with Landsat-based 30 m resolution fire and tree cover datasets for California wildfires from 1986-2021. Rates of TCL rose faster than trends in burned area, with the magnitude of tree cover area loss per unit of area burned increasing by 70% from 0.20 ± 0.05 during 1986-1996 to 0.34 ± 0.10 during 2011-2021. Forest exposure (pre-fire tree cover) within fires increased by 41% from a decadal mean of 23.4% ± 5.5% (1986-1996) to 33.1% ± 7.8% (2011-2021). Increasing forest exposure...

Multi-Criteria Optimization of Energy-Efficient Cementitious Sandwich Panels Building Systems Using Genetic Algorithm

Wed, 23 Apr 2025 00:00:00 +0000

This paper presents results of a study that focuses on developing a genetic algorithm (GA) for multi-criteria optimization of orthotropic, energy-efficient cementitious composite sandwich panels (CSP). The current design concept of all commercially produced CSP systems is based on the assumption that such panels are treated as doubly reinforced sections without the consideration of the three-dimensional truss contribution of the orthotropic panel system. This leads to uneconomical design and underestimating both the strength and stiffness of such system. In this study, two of the most common types of commercially produced sandwich were evaluated both numerically and experimentally and results were used as basis for developing a genetic algorithm optimization process using numerical modeling simulations. In order to develop a sandwich panel with high structural performance, design optimization techniques are needed to achieve higher composite action, while maintaining the favorable...

Seismic Behaviors of Reinforced Concrete Column with Different Axial Compression Ratio Strengthened by Bidirectional Basalt Fiber-Reinforced Polymer (BFRP) Laminates

Wed, 23 Apr 2025 00:00:00 +0000

Seismic Behaviors of Reinforced Concrete Column with Different Axial Compression Ratio Strengthened by Bidirectional Basalt Fiber-Reinforced Polymer (BFRP) Laminates

Freshwater faces a warmer and saltier future from headwaters to coasts: climate risks, saltwater intrusion, and biogeochemical chain reactions

Fri, 11 Apr 2025 00:00:00 +0000

Alongside global climate change, many freshwater ecosystems are experiencing substantial shifts in the concentrations and compositions of salt ions coming from both land and sea. We synthesize a risk framework for anticipating how climate change and increasing salt pollution coming from both land and saltwater intrusion will trigger chain reactions extending from headwaters to tidal waters. Salt ions trigger ‘chain reactions,’ where chemical products from one biogeochemical reaction influence subsequent reactions and ecosystem responses. Different chain reactions impact drinking water quality, ecosystems, infrastructure, and energy and food production. Risk factors for chain reactions include shifts in salinity sources due to global climate change and amplification of salinity pulses due to the interaction of precipitation variability and human activities. Depending on climate and other factors, salt retention can range from 2 to 90% across watersheds globally. Salt retained in...

Microstructure-Based Magneto-Mechanical Modeling of Magnetorheological Elastomer Composites: A Comparable Analysis of Dipole and Maxwell Methods

Thu, 3 Apr 2025 00:00:00 +0000

Magnetorheological elastomers (MREs) are smart composite materials with tunable mechanical properties by ferromagnetic particle interactions. This study applied the microstructure-based dipole and Maxwell methods to evaluate the magneto-mechanical coupling and magnetostrictive responses of MREs, focusing on various particle distributions. The finite element modeling of representative volume elements with fixed volume fractions revealed that the straight chain microstructure exhibits the most significant magnetostrictive effect due to its low initial shear stiffness and significant magnetic force contributions. For particle separations exceeding three radii, the dipole and Maxwell methods yield consistent results for vertically or horizontally aligned particles. For particle separations greater than three radii, the dipole and Maxwell methods produce consistent results for vertically and horizontally aligned particles. However, discrepancies emerge for angled configurations and...

Bedmap3 updated ice bed, surface and thickness gridded datasets for Antarctica

Thu, 3 Apr 2025 00:00:00 +0000

We present Bedmap3, the latest suite of gridded products describing surface elevation, ice-thickness and the seafloor and subglacial bed elevation of the Antarctic south of 60 °S. Bedmap3 incorporates and adds to all post-1950s datasets previously used for Bedmap2, including 84 new aero-geophysical surveys by 15 data providers, an additional 52 million data points and 1.9 million line-kilometres of measurement. These efforts have filled notable gaps including in major mountain ranges and the deep interior of East Antarctica, along West Antarctic coastlines and on the Antarctic Peninsula. Our new Bedmap3/RINGS grounding line similarly consolidates multiple recent mappings into a single, spatially coherent feature. Combined with updated maps of surface topography, ice shelf thickness, rock outcrops and bathymetry, Bedmap3 reveals in much greater detail the subglacial landscape and distribution of Antarctica’s ice, providing new opportunities to interpret continental-scale landscape...

Uncrewed Aerial Vehicle‐Based Multispectral Imagery for River Soil Monitoring

Sat, 29 Mar 2025 00:00:00 +0000

ABSTRACT Flood hazards pose a significant threat to communities and ecosystems alike. Triggered by various factors such as heavy rainfall, storm surges, or rapid snowmelt, floods can wreak havoc by inundating low‐lying areas and overwhelming infrastructure systems. Understanding the feedback between local geomorphology and sediment transport dynamics in terms of the extent and evolution of flood‐related damage is necessary to build a system‐level description of flood hazard. In this research, we present a multispectral imagery‐based approach to broadly map sediment classes and how their spatial extent and relocation can be monitored. The methodology is developed and tested using data collected in the Ahr Valley in Germany during post‐disaster reconnaissance of the July 2021 Western European flooding. Using uncrewed aerial vehicle‐borne multispectral imagery calibrated with laboratory‐based soil characterization, we illustrate how fine and coarse‐grained sediments can be broadly...

Unraveling climate change-induced compound low-solar-low-wind extremes in China

Fri, 31 Jan 2025 00:00:00 +0000

China's pursuit of carbon neutrality targets hinges on a profound shift towards low-carbon energy, primarily reliant on intermittent and variable, yet crucial, solar and wind power sources. In particular, low-solar-low-wind (LSLW) compound extremes present a critical yet largely ignored threat to the reliability of renewable electricity generation. While existing studies have largely evaluated the impacts of average climate-induced changes in renewable energy resources, comprehensive analyses of the compound extremes and, particularly, the underpinning dynamic mechanisms remain scarce. Here we show the dynamic evolution of compound LSLW extremes and their underlying mechanisms across China via coupling multi-model simulations with diagnostic analysis. Our results unveil a strong topographic dependence in the frequency of compound LSLW extremes, with a national average frequency of 16.4 (10th-90th percentile interval ranges from 5.3 to 32.6) days/yr, when renewable energy resources...

Temporal and spatial pattern analysis of escaped prescribed fires in California from 1991 to 2020

Wed, 29 Jan 2025 00:00:00 +0000

BackgroundPrescribed fires play a critical role in reducing the intensity and severity of future wildfires by systematically and widely consuming accumulated vegetation fuel. While the current probability of prescribed fire escape in the United States stands very low, their consequential impact, particularly the large wildfires they cause, raises substantial concerns. The most direct way of understanding this trade-off between wildfire risk reduction and prescribed fire escapes is to explore patterns in the historical prescribed fire records. This study investigates the spatiotemporal patterns of escaped prescribed fires in California from 1991 to 2020, offering insights for resource managers in developing effective forest management and fuel treatment strategies.ResultsThe results reveal that the months close to the beginning and end of the wildfire season, namely May, June, September, and November, have the highest frequency of escaped fires. Under similar environmental conditions,...

Bathymetry of the Antarctic continental shelf and ice shelf cavities from circumpolar gravity anomalies and other data

Mon, 20 Jan 2025 00:00:00 +0000

Bathymetry critically influences the intrusion of warm Circumpolar Deep Water onto the continental shelf and under ice shelf cavities in Antarctica, thereby forcing ice melting, grounding line retreat, and sea level rise. We present a novel and comprehensive bathymetry of Antarctica that includes all ice shelf cavities and previously unmeasured continental shelf areas. The new bathymetry is based on a 3D inversion of a circumpolar compilation of gravity anomalies constrained by measurements from the International Bathymetric Chart of the Southern Ocean, BedMachine Antarctica, and discrete seafloor measurements from seismic and ocean robotic probes. Previously unknown troughs with thicker ice shelf cavities are revealed in many parts of Antarctica, especially East Antarctica. The greater depths of troughs on the continental shelf and ice shelf cavities imply that many glaciers are more vulnerable to ocean subsurface warming than previously thought, which may increase the projections...

The International Bathymetric Chart of the Arctic Ocean Version 5.0

Thu, 2 Jan 2025 00:00:00 +0000

Knowledge about seafloor depth, or bathymetry, is crucial for various marine activities, including scientific research, offshore industry, safety of navigation, and ocean exploration. Mapping the central Arctic Ocean is challenging due to the presence of perennial sea ice, which limits data collection to icebreakers, submarines, and drifting ice stations. The International Bathymetric Chart of the Arctic Ocean (IBCAO) was initiated in 1997 with the goal of updating the Arctic Ocean bathymetric portrayal. The project team has since released four versions, each improving resolution and accuracy. Here, we present IBCAO Version 5.0, which offers a resolution four times as high as Version 4.0, with 100 × 100 m grid cells compared to 200 × 200 m. Over 25% of the Arctic Ocean is now mapped with individual depth soundings, based on a criterion that considers water depth. Version 5.0 also represents significant advancements in data compilation and computing techniques. Despite these improvements,...

L-Band Microwave Satellite Data and Model Simulations Over the Dry Chaco to Estimate Soil Moisture, Soil Temperature, Vegetation, and Soil Salinity

Wed, 4 Dec 2024 00:00:00 +0000

The Dry Chaco in South America is a semi-arid ecoregion prone to dryland salinization. In this region, we investigated coarse-scale surface soil moisture (SM), soil temperature, soil salinity, and vegetation, using L-band microwave brightness temperature (TB) observations and retrievals from the soil moisture ocean salinity (SMOS) and soil moisture active passive satellite missions, Catchment land surface model (CLSM) simulations, and in situ measurements within 26 sampled satellite pixels. Across these 26 sampled pixels, the satellite-based SM outperformed CLSM SM when evaluated against field data, and the forward L-band TB simulations derived from in situ SM and soil temperature performed better than those derived from CLSM estimates when evaluated against SMOS TB observations. The surface salinity for the sampled pixels was on average only 4 mg/g and only locally influenced the TB simulations, when including salinity in the dielectric mixing model of the forward radiative transfer...

Comment on “Improving Bayesian Model Averaging for Ensemble Flood Modeling Using Multiple Markov Chains Monte Carlo Sampling”

Wed, 4 Dec 2024 00:00:00 +0000

Abstract: Huang and Merwade (2023), https://doi.org/10.1029/2023wr034947, hereafter conveniently referred to as HM23, wrongly claim improvement of their method for postprocessing multi‐model water stage predictions using Bayesian Model Averaging (BMA). Their results show all signs of a flawed implementation of the Metropolis algorithm. In this comment I will point out the many mistakes and shortcomings of the BMA methodology of HM23. Their method is deficient, inefficient and ineffective and wrongly quantifies BMA model parameter and predictive uncertainty. Furthermore, HM23 misrepresent BMA literature, articulate a poor understanding of Markov chain Monte Carlo methods and misuse the autocorrelation function for monitoring convergence of the sampled Markov chains. A proper implementation of the random walk Metropolis algorithm would have led HM23 to substantially different results and findings about their ensemble of water stage predictions. The MODELAVG toolbox of Vrugt (2018)...

Distribution‐Based Model Evaluation and Diagnostics: Elicitability, Propriety, and Scoring Rules for Hydrograph Functionals

Wed, 4 Dec 2024 00:00:00 +0000

Distribution forecasts P over future quantities or events are routinely made in hydrology but usually traded for a (likelihood-weighted) mean or median prediction to accommodate error measures or scoring functions such as the mean absolute error or mean squared error. Case in point is the so-called KG efficiency (KGE) of Gupta et al. (2009, https://doi.org/10.1016/j.jhydrol.2009.08.003) and improvements thereof (Lamontagne et al., 2020, https://doi.org/10.1029/2020wr027101), which have rapidly gained popularity among hydrologists as alternative scoring functions to the commonly used Nash and Sutcliffe (1970, https://doi.org/10.1016/0022-1694(70)90255-6) efficiency, but are equally exclusive in how they quantify model performance using only single-valued output of the quantities of interest. This point-valued mapping necessarily implies a loss of information about model performance. This paper advocates the use of probabilistic watershed model training, evaluation and...

Using climate information as covariates to improve nonstationary flood frequency analysis in Brazil

Wed, 4 Dec 2024 00:00:00 +0000

Climatic drivers of floods have been widely used to improve nonstationary flood frequency analysis (FFA). However, the forecast ability of nonstationary FFA with out-of-sample prediction has not been comprehensively evaluated. We use 379 flood records from Brazil to assess the ability of process-informed nonstationary models for out-of-sample FFA using the generalized extreme value (GEV) distribution. Five drivers of floods are used as covariates: annual temperature, El Nino Southern Oscillation, annual rainfall, annual maximum rainfall, and annual maximum soil moisture content. Our results reveal that a nonstationary model is preferable when there is a significant correlation between flood and climate covariates in both the training period and full record. The rainfall-based covariates lead to better out-of-sample nonstationary FFA models. These findings highlight that using climate information as covariates in nonstationary FFA is a promising approach for estimating future floods...

Soil Moisture‐Cloud‐Precipitation Feedback in the Lower Atmosphere From Functional Decomposition of Satellite Observations

Wed, 4 Dec 2024 00:00:00 +0000

The feedback of topsoil moisture (SM) content on convective clouds and precipitation is not well understood and represented in the current generation of weather and climate models. Here, we use functional decomposition of satellite-derived SM and cloud vertical profiles (CVP) to quantify the relationship between SM and the vertical distribution of cloud water in the central US. High-dimensional model representation is used to disentangle the contributions of SM and other land-surface and atmospheric variables to the CVP. Results show that the sign and strength of the SM-cloud-precipitation feedback varies with cloud height and time lag and displays a large spatial variability. Positive anomalies in antecedent 7-hr SM and land-surface temperature enhance cloud reflectivity up to 4 dBZ in the lower atmosphere about 1-3 km above the surface. Our approach presents new insights into the SM-cloud-precipitation feedback and aids in the diagnosis of land-atmosphere interactions simulated...

Identification of key parameters controlling demographicallystructured vegetation dynamics in a Land Surface Model [CLM4.5(ED)]

Wed, 4 Dec 2024 00:00:00 +0000

Abstract. Vegetation plays a key role in regulating global carbon cycles and is a key component of the Earth System Models (ESMs) aimed to project Earth's future climates. In the last decade, the vegetation component within ESMs has witnessed great progresses from simple 'big-leaf' approaches to demographically-structured approaches, which has a better representation of plant size, canopy structure, and disturbances. The demographically-structured vegetation models are typically controlled by a large number of parameters, and sensitivity analysis is generally needed to quantify the impact of each parameter on the model outputs for a better understanding of model behaviors. In this study, we use the Fourier Amplitude Sensitivity Test (FAST) to diagnose the Community Land Model coupled to the Ecosystem Demography Model, or CLM4.5(ED). We investigate the first and second order sensitivities of the model parameters to outputs that represent simulated growth and mortality as well as...

Mechanical Properties, Durability, and Structural Applications of Rubber Concrete: A State-of-the-Art-Review

Wed, 20 Nov 2024 00:00:00 +0000

Substituting rubber particles for a portion of the standard coarse aggregates in concrete is regarded as a sustainable solution for tackling the issue of waste-tires disposal. In order to assess the structural performance of rubber concrete (RC), many studies have been conducted on the proportions, mechanical properties, curing conditions, usages, and serviceability performance of the material over the decades. This review systematically summarizes the mechanical properties (e.g., static and dynamic), testing method, and durability of RC, emphasizing its dynamic characteristics from the perspectives of material and component. The inclusion of rubber particles weakens the static properties of the concrete, while the low module of inherent rubbers improves the concrete dynamic properties, such as low stiffness degradation, high strain-rate sensitivity, excellent energy dissipations, and good ductility. With the increase in the strain rate, the improvement in energy absorption and...

The anthropogenic salt cycle

Mon, 18 Nov 2024 00:00:00 +0000

Increasing salt production and use is shifting the natural balances of salt ions across Earth systems, causing interrelated effects across biophysical systems collectively known as freshwater salinization syndrome. In this Review, we conceptualize the natural salt cycle and synthesize increasing global trends of salt production and riverine salt concentrations and fluxes. The natural salt cycle is primarily driven by relatively slow geologic and hydrologic processes that bring different salts to the surface of the Earth. Anthropogenic activities have accelerated the processes, timescales and magnitudes of salt fluxes and altered their directionality, creating an anthropogenic salt cycle. Global salt production has increased rapidly over the past century for different salts, with approximately 300 Mt of NaCl produced per year. A salt budget for the USA suggests that salt fluxes in rivers can be within similar orders of magnitude as anthropogenic salt fluxes, and there can...

Freshwater salinization syndrome limits management efforts to improve water quality

Thu, 7 Nov 2024 00:00:00 +0000

Freshwater Salinization Syndrome (FSS) refers to groups of biological, physical, and chemical impacts which commonly occur together in response to salinization. FSS can be assessed by the mobilization of chemical mixtures, termed "chemical cocktails", in watersheds. Currently, we do not know if salinization and mobilization of chemical cocktails along streams can be mitigated or reversed using restoration and conservation strategies. We investigated 1) the formation of chemical cocktails temporally and spatially along streams experiencing different levels of restoration and riparian forest conservation and 2) the potential for attenuation of chemical cocktails and salt ions along flowpaths through conservation and restoration areas. We monitored high-frequency temporal and longitudinal changes in streamwater chemistry in response to different pollution events (i.e., road salt, stormwater runoff, wastewater effluent, and baseflow conditions) and several types of watershed...

Spatial variability in Arctic–boreal fire regimes influenced by environmental and human factors

Wed, 30 Oct 2024 00:00:00 +0000

Wildfire activity in Arctic and boreal regions is rapidly increasing, with severe consequences for climate and human health. Regional long-term variations in fire frequency and intensity characterize fire regimes. The spatial variability in Arctic–boreal fire regimes and their environmental and anthropogenic drivers, however, remain poorly understood. Here we present a fire tracking system to map the sub-daily evolution of all circumpolar Arctic–boreal fires between 2012 and 2023 using 375 m Visible Infrared Imaging Radiometer Suite active fire detections and the resulting dataset of the ignition time, location, size, duration, spread and intensity of individual fires. We use this dataset to classify the Arctic–boreal biomes into seven distinct ‘pyroregions’ with unique climatic and geographic environments. We find that these pyroregions exhibit varying responses to environmental drivers, with boreal North America, eastern Siberia and northern tundra regions showing the highest...

Understanding Party Size in Ride-Hailing: Solo Versus Group Travel

Sat, 26 Oct 2024 00:00:00 +0000

Emerging mobility technologies, like ride-hailing, are underrepresented in travel behavior surveys. Consequently, travel demand modelers have often resorted to simplistic solo-traveler assumptions or relied on aggregate trip size factors within activity- and agent-based models. To address this gap and help modelers understand ride-hail party size, this study analyzed data collected from a 2021 to 2022 household travel survey in the greater Twin Cities (Minneapolis–St. Paul, MN) region. Ride-hail trips were paired with person-, household-, and trip-level attributes to provide context for both single-party and multiparty ride-hailing. Binary logistic regression models indicated that shared micromobility users, households with more children, renters in large multifamily buildings, and individuals with at most a high school education were significantly more likely to use ride-hailing for group travel than for solo trips. A hurdle regression for party size count revealed that lower-income...

Characterizing firebrands and their kinematics during lofting

Thu, 24 Oct 2024 00:00:00 +0000

Spot fires pose a major risk and add to the already complex physics, which makes fire spread so hard to predict, especially in the wildland urban interface. Firebrands can not only cross fuel breaks and thwart other suppression efforts but also directly damage infrastructure and block evacuation routes. Transport models and computational fluid dynamics tools often make simplifications when predicting spot fire risk, but there is a relative lack of experimental data to validate such parameterizations. To this end, we present a field experiment performed at the University of California Berkeley Blodgett Research Forest in California where we recorded the flame and firebrands emanating from a nighttime hand-drawn pile fire using high-frequency imaging. We used image-processing to characterize the fire intensity and turbulence as well as particle tracking velocimetry to measure ejected firebrand kinematics as they are lofted by the plume. We further collected embers that settled around...

A Single Compartment Relaxed Eddy Accumulation Method

Thu, 24 Oct 2024 00:00:00 +0000

Abstract The relaxed eddy accumulation (REA) method is a widely‐known technique that measures turbulent fluxes of scalar quantities. The REA technique has been used to measure turbulent fluxes of various compounds, such as methane, ethene, propene, butene, isoprene, nitrous oxides, ozone, and others. The REA method requires the accumulation of scalar concentrations in two separate compartments that conditionally sample updrafts and downdraft events. It is demonstrated here that the assumptions behind the conventional or two‐compartment REA approach allow for one‐compartment sampling, therefore called a one compartment or 1‐C‐REA approach, thereby expanding its operational utility. The one‐compartment sampling method is tested across various land cover types and atmospheric stability conditions, and it is found that the one‐compartment REA can provide results comparable to those determined from conventional two‐compartment REA. This finding enables rapid expansion and practical...

A State-Space Method for Vibration of Double-Beam Systems with Variable Cross Sections

Wed, 9 Oct 2024 00:00:00 +0000

In this paper, a state-space method for double-beam systems with variable cross sections is developed, making it possible to calculate the transverse vibration of the double-beams accurately and effectively. Due to the variability in the double-beam cross sections with the viscoelastic interlayer in between, the governing equations of vibration for the systems become highly coupled partial differential equations, making the problem difficult to solve. A basic double-beam system is introduced to modify the original governing equations to two inhomogeneous differential equations. Given the separation of variables, several mode-shape coefficients and a state variable are defined to construct the state-space equations. The coupling terms and variables are transferred into the constant coefficient matrix of the state-space equations, decoupling them. Numerical procedures are presented to solve the state-space equations to obtain homogenous and inhomogeneous solutions, including the...

How urban form impacts flooding

Mon, 9 Sep 2024 00:00:00 +0000

Urbanization and climate change are contributing to severe flooding globally, damaging infrastructure, disrupting economies, and undermining human well-being. Approaches to make cities more resilient to floods are emerging, notably with the design of flood-resilient structures, but relatively little is known about the role of urban form and its complexity in the concentration of flooding. We leverage statistical mechanics to reduce the complexity of urban flooding and develop a mean-flow theory that relates flood hazards to urban form characterized by the ground slope, urban porosity, and the Mermin order parameter which measures symmetry in building arrangements. The mean-flow theory presents a dimensionless flood depth that scales linearly with the urban porosity and the order parameter, with different scaling for disordered square- and hexagon-like forms. A universal scaling is obtained by introducing an effective mean chord length representative of the unobstructed downslope...

Developing an Effective and Engaging Concept-driven Approach to Teaching Structural Design

Wed, 28 Aug 2024 00:00:00 +0000

Developing an Effective and Engaging Concept-driven Approach to Teaching Structural Design

Exploring Educational Needs and Practices in Structural Analysis

Wed, 28 Aug 2024 00:00:00 +0000

Exploring Educational Needs and Practices in Structural Analysis

Interactive Online Figures for the Core Concepts in Structural Steel Design

Wed, 28 Aug 2024 00:00:00 +0000

Interactive Online Figures for the Core Concepts in Structural Steel Design

Experimental and numerical investigation on the seismic behavior of plane frames with special-shaped concrete-filled steel tubular columns

Wed, 28 Aug 2024 00:00:00 +0000

The seismic behavior of (plane) frames with special-shaped concrete-filled steel tubular (CFST) columns (SCFSTFs), H-shaped steel beams, and exterior diaphragm connections was investigated experimentally and numerically in this study. Double-bay two-story SCFSTFs with a scale ratio of 1/2 were tested under constant vertical compressive load and cyclic horizontal loads (or displacements), which is a pseudo-static experiment considering the axial compression ratio. Based on the experimental results, failure modes, bearing capacity, hysteretic curves, skeleton curves, energy dissipation, ductility, rigidity degradation, and strength degradation of SCFSTFs were investigated. As a result, a typical strong column-weak beam failure mode was observed; degradation in strength and rigidity were minimal, and the energy dissipation capacity and ductility of SCFSTFs were adequate, demonstrating excellent seismic performance. Besides, energy dissipation capacity and horizontal load bearing...

Resistance of special-shaped concrete-filled steel tube columns under compression and bending

Wed, 28 Aug 2024 00:00:00 +0000

Resistance of special-shaped concrete-filled steel tube columns under compression and bending

Using Buckling-Restrained Braces on Long-Span Bridges. I: Full-Scale Testing and Design Implications

Wed, 28 Aug 2024 00:00:00 +0000

Using Buckling-Restrained Braces on Long-Span Bridges. I: Full-Scale Testing and Design Implications

Using Buckling-Restrained Braces on Long-Span Bridges. II: Feasibility and Development of a Near-Fault Loading Protocol

Wed, 28 Aug 2024 00:00:00 +0000

Using Buckling-Restrained Braces on Long-Span Bridges. II: Feasibility and Development of a Near-Fault Loading Protocol

Board 39: Student Opinions on Example Problem 'Solution Walkthroughs' for Civil Engineering Topics

Wed, 28 Aug 2024 00:00:00 +0000

Board 39: Student Opinions on Example Problem 'Solution Walkthroughs' for Civil Engineering Topics

Fighting “Plug and Chug” Structural Design through Effective and Experiential Demonstrations

Wed, 28 Aug 2024 00:00:00 +0000

Fighting “Plug and Chug” Structural Design through Effective and Experiential Demonstrations

Improving Student Writing Outcomes Through Dynamic Feedback, Design Oriented Projects and Curriculum Modification

Wed, 28 Aug 2024 00:00:00 +0000

Improving Student Writing Outcomes Through Dynamic Feedback, Design Oriented Projects and Curriculum Modification

Influence of soil characteristics and metal(loid)s on antibiotic resistance genes in green stormwater infrastructure in Southern California

Thu, 15 Aug 2024 00:00:00 +0000

The synergetic effects of metal(loid)s and soil characteristics on bacterial antibiotic resistance genes (ARGs) in green stormwater infrastructure (GSI) has been relatively understudied. Surface soil samples from six GSIs in Southern California over three time periods were assessed for selected ARGs, class 1 integron-integrase genes (intI1), 16S rRNA genes, and bioavailable and total concentrations of nine metal(loid)s, to investigate the relationships among ARGs, soil characteristics, and co-occurring metal(loid)s. Significant correlations existed among relative gene abundances (sul1, sul2, tetW, and intI1), total metal(loid)s (arsenic, copper, lead, vanadium, and zinc), and bioavailable metal(loid) (arsenic) (r = 0.29-0.61, p_adj < 0.05). Additionally, soil texture, organic matter, and nutrients within GSI appeared to be significantly correlated with relative gene abundances of sul1, sul2, and tetW (r = -0.57 to 0.59, p_adj < 0.05)....

Assessing Public Opinions of and Interest in Bidirectional Electric Vehicle Charging Technologies: A U.S. Perspective

Tue, 6 Aug 2024 00:00:00 +0000

An increasing number of battery-electric vehicles (BEVs) have bidirectional charging technology that provides new benefits to motorists, homeowners, and power grid operators. A web-based survey investigates the willingness of over 300 Americans to pay for added bidirectional charging features, namely, vehicle-to-load (V2L), vehicle-to-home (V2H), and vehicle-to-grid (V2G) technologies, along with their expected use frequency. Summary statistics suggest that Americans are willing to pay (WTP) an average of $280 and $776 on top of the price of a new car for V2L and V2H, respectively. About 51.3% would let their power company discharge their vehicle via V2G during grid emergencies if compensated and guaranteed a minimum battery level. Interval regression and ordered probit equations explain how demographics, travel patterns, and attitudinal variables affect the response variables, including WTP for bidirectional charging features and expected reliance on technology. The statistically...

DOME: Drone-assisted Monitoring of Emergent Events For Wildland Fire Resilience

Sun, 4 Aug 2024 00:00:00 +0000

We develop a Drone-assisted Monitoring system, DOME, that gathers real-time data for situational awareness in emergent and evolving events. The driving use case for this work is a prescribed burn event (Rx fire), o ften u sed t o r educe h azardous f uels i n forests. DOME coordinates the use of multiple heterogeneous drone platforms to support the observation of emergent physical phenomena (e.g., fire spread) by leveraging domain expert input and physics-based modeling/simulation methods. We propose an executable rule-based system for drone task generation; here, a high-level mission specification utilizes physics-based models for fire spread prediction and automatically generates monitoring instructions with locations, periods, and frequency for drones. DOME integrates algorithms for task allocation (mapping tasks to drones) and flight path planning while considering trade-offs between sensing coverage and accuracy. In addition, DOME will guide in-flight drones to store and...

QuIC-IoT: Model-Driven Short-Term IoT Deployment for Monitoring Physical Phenomena

Sun, 4 Aug 2024 00:00:00 +0000

The Internet-of-things ecosystem has been a driving force in the creation of smart communities where a variety of physical phenomena can be monitored continuously, e.g., air quality, traffic conditions on roads, energy consumption in buildings, etc. In this paper, we address how IoT can be quickly and effectively deployed for short-term and sporadic events (e.g., fire spread in a wildland area and flood propagation), where monitoring the evolving event is critical. In particular, we propose QuIC-IoT, a model-driven planning platform that aims to temporarily deploy a custom IoT infrastructure for monitoring short-term events, where phenomena-spread is driven by models that are physics-based. Our driving usecase event is a quasi-planned prescribed fire or RxFire - this is a wildfire resilience technique where intentional small fires are ignited apriori by forestry personnel to destroy fuel and help contain the spread of actual wildfires. Anomalies that may occur during these quasi-planned...

Assessing the Turbulence Kinetic Energy Budget in the Boundary Layer Using WRF-LES: Impact of Momentum Perturbation

Sun, 4 Aug 2024 00:00:00 +0000

Mesoscale-to-Large Eddy Simulation (LES) grid nesting is an important tool for many atmospheric model applications, ranging from wind energy to wildfire spread studies. Different techniques are used in such applications to accelerate the development of turbulence in the LES domain. Here, we explore the impact of a simple and computationally efficient Stochastic Cell Perturbation method (SCPM) to accelerate the generation of turbulence in the Weather Research and Forecasting (WRF) LES model on the Turbulence Kinetic Energy (TKE) budget. In a convective boundary layer, we study the variation of TKE budget terms under the initial conditions of the Scaled Wind Farm Technology (SWiFT) facility located in West Texas. In this study, WRF LES is used with a horizontal grid resolution of 12 m, and is one-way nested within an idealized mesoscale domain. It is crucial to understand how forced perturbation shifts the balance between the terms of the TKE budget. Here, we quantify the shear...

Quantifying small-scale anisotropy in turbulent flows

Sun, 4 Aug 2024 00:00:00 +0000

The verification of whether small-scale turbulence is isotropic remains a grand challenge. The difficulty arises because the presence of small-scale anisotropy is tied to the dissipation tensor, whose components require the full three-dimensional information of the flow field in both high spatial and temporal resolution, a condition rarely satisfied in turbulence experiments, especially during field scale measurement of atmospheric turbulence. To circumvent this issue, an intermittency-anisotropy framework is proposed through which we successfully extract the features of small-scale anisotropy from single-point measurements of turbulent time series by exploiting the properties of small-scale intermittency. Specifically, this framework quantifies anisotropy by studying the contrasting effects of burstlike activities on the scalewise production of turbulence kinetic energy between the horizontal and vertical directions. The veracity of this approach is tested by applying it over...

Experiments of Main Parameters Affecting the Erosive Behavior of Self-Excited Oscillating Abrasive Water Jets: Length of Self-Oscillation Chamber, Jet Pressure, Abrasive Fluid Velocity, and Abrasive Grain Size

Fri, 2 Aug 2024 00:00:00 +0000

To enhance the erosion efficiency in traditional abrasive water jet processing, an abrasive water jet processing method based on self-excited fluid oscillation is proposed. Traditional abrasive water jet methods suffer from reduced jet kinetic energy due to the presence of a stagnation layer, which hinders efficient material removal. By integrating a self-oscillation chamber into the conventional abrasive water jet nozzle, the continuous jet is transformed into a pulsed jet, thereby increasing the jet velocity and enhancing the kinetic energy of the process. This modification aims to improve material removal efficiency. Using Ansys Fluent, we simulated the material removal efficiency on workpiece surfaces with varying lengths of self-oscillation chambers. The simulation results reveal that the optimal length of the self-oscillation chamber for maximum erosion is 4 mm. SiC materials were used to evaluate the impact of self-oscillation chamber length (L), jet pressure (P), abrasive...

Water and climate: Recognize anthropogenic drought

Wed, 31 Jul 2024 00:00:00 +0000

Water and climate: Recognize anthropogenic drought

Nonstationary frequency analysis of extreme precipitation: Embracing trends in observations

Tue, 11 Jun 2024 00:00:00 +0000

Knowledge of the recurrence intervals of precipitation extremes is vital for infrastructure design, risk assessment, and insurance planning. However, trends and shifts in rainfall patterns globally pose challenges to the application of extreme value analysis (EVA) which relies critically on the assumption of stationarity. In this paper, we explore: (1) the suitability of nonstationary (NS) models in the presence of statistically significant trends, and (2) their potential in modeling out-of-sample data to improve frequency analysis of extreme precipitation. We analyze the benefits of using a nonstationary Generalized Extreme Value (GEV) model for annual extreme precipitation records from Southern Brazil. The location of the GEV distribution is allowed to change with time. The unknown GEV model parameters are estimated using Bayesian techniques coupled with Markov chain Monte Carlo simulation. Next, we use GAME sampling to compute the evidence (and their ratios, the so-called Bayes...

Widespread seawater intrusions beneath the grounded ice of Thwaites Glacier, West Antarctica

Sat, 8 Jun 2024 00:00:00 +0000

Warm water from the Southern Ocean has a dominant impact on the evolution of Antarctic glaciers and in turn on their contribution to sea level rise. Using a continuous time series of daily-repeat satellite synthetic-aperture radar interferometry data from the ICEYE constellation collected in March-June 2023, we document an ice grounding zone, or region of tidally controlled migration of the transition boundary between grounded ice and ice afloat in the ocean, at the main trunk of Thwaites Glacier, West Antarctica, a strong contributor to sea level rise with an ice volume equivalent to a 0.6-m global sea level rise. The ice grounding zone is 6 km wide in the central part of Thwaites with shallow bed slopes, and 2 km wide along its flanks with steep basal slopes. We additionally detect irregular seawater intrusions, 5 to 10 cm in thickness, extending another 6 km upstream, at high tide, in a bed depression located beyond a bedrock ridge that impedes the glacier retreat. Seawater...

Safe streets for some: A review of local active transportation responses across the U.S. during the COVID-19 pandemic

Thu, 6 Jun 2024 00:00:00 +0000

Introduction & research objectives: The COVID-19 pandemic significantly disrupted daily travel. This paper contrasts 51 US cities' responses, namely street reallocation criteria and messaging related to physical activity (PA) and active transportation (AT) during the early months of the pandemic. This study can be utilized by cities for aiding in the creation of locally responsive policies that acknowledge and remedy a lack of safe active transportation. Methods: A content analysis review was conducted of city orders and documents related to PA or AT for the largest city by population in all 50 US states and the District of Columbia. Authoritative documents issued from each city's public health declaration (ca. March 2020) to September 2020 were reviewed. The study obtained documents from two crowdsourced datasets and municipal websites. Descriptive statistics were used to compare policies and strategies, with a focus on reallocation of street space. Results: A total of 631...

We need a solid scientific basis for nature-based climate solutions in the United States

Thu, 6 Jun 2024 00:00:00 +0000

We need a solid scientific basis for nature-based climate solutions in the United States

Shared E-Scooter Trajectory Analysis During the COVID-19 Pandemic in Austin, Texas

Thu, 6 Jun 2024 00:00:00 +0000

By March of 2020, most cities worldwide had enacted stay-at-home public health orders to slow the spread of COVID-19. Restrictions on nonessential travel had extensive impacts across the transportation sector in the short term. This study explores the effects of COVID-19 on shared e-scooters by analyzing route trajectory data in the pre- and during-pandemic periods in Austin, TX, from a single provider. Although total shared e-scooter trips decreased during the pandemic, partially owing to vendors pulling out of the market, this study found average trip length increased, and temporal patterns of this mode did not meaningfully change. A count model of average daily trips by road segment found more trips on segments with sidewalks and bus stops during the pandemic than beforehand. More trips were observed on roads with lower vehicle miles traveled and fewer lanes, which might suggest more cautious travel behavior since there were fewer trips in residential neighborhoods. Stay-at-home...

Topographic hydro-conditioning to resolve surface depression storage and ponding in a fully distributed hydrologic model

Tue, 4 Jun 2024 00:00:00 +0000

Land surface depressions play a central role in the transformation of rainfall to ponding, infiltration and runoff, yet digital elevation models (DEMs) used by spatially distributed hydrologic models that resolve land surface processes rarely capture land surface depressions at spatial scales relevant to this transformation. Methods to generate DEMs through processing of remote sensing data, such as optical and light detection and ranging (LiDAR) have favored surfaces without depressions to avoid adverse slopes that are problematic for many hydrologic routing methods. Here we present a new topographic conditioning workflow, Depression-Preserved DEM Processing (D2P) algorithm, which is designed to preserve physically meaningful surface depressions for depression-integrated and efficient hydrologic modeling. D2P includes several features: (1) an adaptive screening interval for delineation of depressions, (2) the ability to filter out anthropogenic land surface features (e.g., bridges),...

Equitable infrastructure: Achieving resilient systems and restorative justice through policy and research innovation

Thu, 23 May 2024 00:00:00 +0000

Recent major investments in infrastructure in the United States and globally present a crucial opportunity to embed equity within the heart of resilient infrastructure decision-making. Yet there is a notable absence of frameworks within the engineering and scientific fields for integrating equity into planning, design, and maintenance of infrastructure. Additionally, whole-of-government approaches to infrastructure, including the Justice40 Initiative, mimic elements of process management that support exploitative rather than exploratory innovation. These and other policies risk creating innovation traps that limit analytical and engineering advances necessary to prioritize equity in decision-making, identification and disruption of mechanisms that cause or contribute to inequities, and remediation of historic harms. Here, we propose a three-tiered framework toward equitable and resilient infrastructure through restorative justice, incremental policy innovation, and exploratory...

Methane Hydrate Structure I Dissociation Process and Free Surface Analysis

Mon, 20 May 2024 00:00:00 +0000

Methane hydrates are crystalline solids of water that contain methane molecules trapped inside their molecular cavities. Gas hydrates with methane as a guest molecule form structure I hydrates with two small dodecahedral cages and six tetra decahedral large cages. This study assesses the influence of occupation and the behavior of methane release from the molecular perspective during the dissociation process, particularly for the purpose of testing a series of molecular dynamics simulations. The dissociation cases conducted include an ideal 4 × 4 × 4 and 2 × 2 × 2 supercell methane hydrate system while inducing dissociation with two different types of temperature-rising functions for understanding the limitation and capability. These temperature-rising functions are temperature ramping and a single temperature step simulating in 5-7 various conditions. Temperature step results showed the earliest dissociation starting 50 ps into the simulation at an ΔT of 100 K, while at...

Investigating Fire–Atmosphere Interaction in a Forest Canopy Using Wavelets

Wed, 8 May 2024 00:00:00 +0000

Wildland fire–atmosphere interaction generates complex turbulence patterns, organized across multiple scales, which inform fire-spread behaviour, firebrand transport, and smoke dispersion. Here, we utilize wavelet-based techniques to explore the characteristic temporal scales associated with coherent patterns in the measured temperature and the turbulent fluxes during a prescribed wind-driven (heading) surface fire beneath a forest canopy. We use temperature and velocity measurements from tower-mounted sonic anemometers at multiple heights. Patterns in the wavelet-based energy density of the measured temperature plotted on a time–frequency plane indicate the presence of fire-modulated ramp–cliff structures in the low-to-mid-frequency band (0.01–0.33 Hz), with mean ramp durations approximately 20% shorter and ramp slopes that are an order of magnitude higher compared to no-fire conditions. We then investigate heat- and momentum-flux events near the canopy top through a cross-wavelet...

Impact of Momentum Perturbation on Convective Boundary Layer Turbulence

Wed, 8 May 2024 00:00:00 +0000

Abstract Mesoscale‐to‐microscale coupling is an important tool for conducting turbulence‐resolving multiscale simulations of realistic atmospheric flows, which are crucial for applications ranging from wind energy to wildfire spread studies. Different techniques are used to facilitate the development of realistic turbulence in the large‐eddy simulation (LES) domain while minimizing computational cost. Here, we explore the impact of a simple and computationally efficient Stochastic Cell Perturbation method using momentum perturbation (SCPM‐M) to accelerate turbulence generation in boundary‐coupled LES simulations using the Weather Research and Forecasting model. We simulate a convective boundary layer (CBL) to characterize the production and dissipation of turbulent kinetic energy (TKE) and the variation of TKE budget terms. Furthermore, we evaluate the impact of applying momentum perturbations of three magnitudes below, up to, and above the CBL on the TKE budget terms. Momentum...

Evaluating the performance of WRF in simulating winds and surface meteorology during a Southern California wildfire event

Wed, 8 May 2024 00:00:00 +0000

The intensity and frequency of wildfires in California (CA) have increased in recent years, causing significant damage to human health and property. In October 2007, a number of small fire events, collectively referred to as the Witch Creek Fire or Witch Fire started in Southern CA and intensified under strong Santa Ana winds. As a test of current mesoscale modeling capabilities, we use the Weather Research and Forecasting (WRF) model to simulate the 2007 wildfire event in terms of meteorological conditions. The main objectives of the present study are to investigate the impact of horizontal grid resolution and planetary boundary layer (PBL) scheme on the model simulation of meteorological conditions associated with a Mega fire. We evaluate the predictive capability of the WRF model to simulate key meteorological and fire-weather forecast parameters such as wind, moisture, and temperature. Results of this study suggest that more accurate predictions of temperature and wind speed...

Methodology for Assessing Retrofitted Hydrogen Combustion and Fuel Cell Aircraft Environmental Impacts

Wed, 1 May 2024 00:00:00 +0000

Hydrogen (H2) combustion and solid oxide fuel cells (SOFCs) can potentially reduce aviation-produced greenhouse gas emissions compared to kerosene propulsion. This paper outlines a methodology for evaluating performance and emission tradeoffs when retrofitting conventional kerosene-powered aircraft with lower-emissionH2 combustion and SOFC hybrid alternatives. The proposed framework presents a constant-range approach for designing liquid hydrogen fuel tanks, considering insulation, sizing, center of gravity, and power constraints. A lifecycle assessment evaluates greenhouse gas emissions and contrail formation effects for carbon footprint mitigation, while a cost analysis examines retrofit implementation consequences. A Cessna Citation 560XLS+ case study shows a 5% mass decrease for H2 combustion and a 0.4% mass decrease for the SOFC hybrid, at the tradeoff of removing three passengers. The lifecycle analysis of green hydrogen in aviation reveals a significant reduction in CO2...

Advancing Precipitation Estimation, Prediction and Impact Studies

Wed, 10 Apr 2024 00:00:00 +0000

Advancing Precipitation Estimation, Prediction and Impact Studies

The time validity of Philip's two‐term infiltration equation: An elusive theoretical quantity?

Wed, 20 Mar 2024 00:00:00 +0000

The two-term infiltration equation (Formula presented.) is commonly used to determine the sorptivity, (Formula presented.) (Formula presented.), and product, (Formula presented.) (Formula presented.), of the dimensionless multiple (Formula presented.) and saturated soil hydraulic conductivity (Formula presented.) (Formula presented.) from cumulative vertical infiltration measurements (Formula presented.) (L) at times (Formula presented.) (T). This reduced form of the quasi-analytical power series solution of Richardson's equation of Philip enjoys a solid physical underpinning but at the expense of a limited time validity. Using simulated infiltration data, Jaiswal et al. have shown this time validity to equal about 2.5 cm of cumulative infiltration. The goals of this work are twofold. First, we investigate the extent to which cumulative infiltration measurements larger than 2.5 cm bias the estimates of (Formula presented.) and (Formula presented.). Second, we investigate...

Reply to Comment by W. Knoben and M. Clark on “The Treatment of Uncertainty in Hydrometric Observations: A Probabilistic Description of Streamflow Records”

Wed, 20 Mar 2024 00:00:00 +0000

In this Reply, we address the concerns of Knoben and Clark (2023, https://doi.org/10.1029/2022WR034294) or KC23 that “the assumptions needed to effectively use difference-based variance estimation methods are not always met by hourly streamflow records.” There should be little doubt that the assumptions of our difference-based estimator will sometimes be violated in hourly streamflow records but the results from de Oliveira and Vrugt (2022, https://doi.org/10.1029/2022wr032263) and confirmed by the findings in our Reply show that such violations are sporadic enough not to affect much the error variance estimates. Snowmelt as pointed out by KC23 (https://doi.org/10.1029/2022WR034294) may not have received sufficient attention in our paper, yet their 365-day record is simply not long enough to demonstrate bias of our discharge error variance estimates (and their dependence on flow level). This would require analysis of a much longer, multi-year, streamflow record of a snowmelt-driven...

Global‐Scale Convergence Obscures Inconsistencies in Soil Carbon Change Predicted by Earth System Models

Wed, 20 Mar 2024 00:00:00 +0000

Soil carbon (C) responses to environmental change represent a major source of uncertainty in the global C cycle. Feedbacks between soil C stocks and climate drivers could impact atmospheric CO2 levels, further altering the climate. Here, we assessed the reliability of Earth system model (ESM) predictions of soil C change using the Coupled Model Intercomparison Project phases 5 and 6 (CMIP5 and CMIP6). ESMs predicted global soil C gains under the high emission scenario, with soils taking up 43.9 Pg (95% CI: 9.2–78.5 Pg) C on average during the 21st century. The variation in global soil C change declined significantly from CMIP5 (with average of 48.4 Pg [95% CI: 2.0–94.9 Pg] C) to CMIP6 models (with average of 39.3 Pg [95% CI: 23.9–54.7 Pg] C). For some models, a small C increase in all biomes contributed to this convergence. For other models, offsetting responses between cold and warm biomes contributed to convergence. Although soil C predictions appeared to converge in CMIP6,...

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