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Cover page of Combining complementary observing systems to produce a basin-scale network for monitoring upper-ocean transport

Combining complementary observing systems to produce a basin-scale network for monitoring upper-ocean transport

(2021)

The high-resolution expendable bathythermograph (HR-XBT) network measures temperature down to approximately 800 m along fixed transects. In comparison, Argo floats are distributed throughout the global ocean and measure temperature and salinity down to approximately 2000 m. Over the 2004-2019 period, the HR-XBT network tended to have a greater sampling density near the coast, while Argo sampling density was generally equivalent to, or greater than, the HR-XBT network in the ocean interior. To take advantage of the benefits of each of these observing systems, a method for combining measurements from HR-XBT, Argo, and satellite altimetry observations was implemented. This method produced estimates of geostrophic velocity and transport in the upper 800 m normal to the HR-XBT transects in the Indian and Pacific Oceans over an approximately 16 year period at high spatial (0.1° along-transect spacing) and temporal (1 month) resolutions. The combined method better resolved the mean geostrophic velocity and transport in the western boundary currents and their recirculations compared to estimates from a 2004-2018 mean high-resolution climatology computed using only Argo data. An additional benefit of the combined method is that it provides a monthly time series of velocity and transport for each HR-XBT transect. This monthly time series captures the temporal variability and will allow for examination of possible drivers of ocean transport.

Cover page of Decadal Strengthening of Interior Flow of North Atlantic Deep Water Observed by GRACE Satellites

Decadal Strengthening of Interior Flow of North Atlantic Deep Water Observed by GRACE Satellites

(2020)

The Gravity Recovery and Climate Experiment (GRACE) satellite mission provides information on changes to the Earth’s gravity field, including ocean mass. Long-term trends in the GRACE data are often considered unreliable due to uncertainties in the corrections made to calculate ocean mass from the raw measurements. Here, we use an independent estimate of ocean mass from satellite altimetry and in situ density data from five mooring sites and repeat hydrography to validate trends in GRACE over the North Atlantic, finding substantial agreement between the methods. The root mean square difference between ocean mass changes calculated with this method from the mooring data and those measured by GRACE is 3.5 mm/decade, much lower than the mean signal of 15.6±1.8 mm/decade for GRACE and 17.8±5.2 mm/decade for the altimetry-mooring estimate. The GRACE ocean mass data are then used to study the change in the deep circulation of the North Atlantic between the 2002/04/01-2009/03/31 and 2010/04/01-2017/03/31 periods, revealing a large-scale anticyclonic circulation anomaly off the North American coast. The change is associated with an increase of 13.9 ± 3.3 Sv (1Sv = 106 m3 s −1) of southward North Atlantic Deep Water flow in the interior between 30◦N and 40◦N, largely balanced by a northward anomaly of 10.7±3.3 Sv for the boundary circulation.  This implies an increased importance of interior pathways compared to the Deep Western Boundary Current for the spreading of North Atlantic Deep Water, which constitutes the lower limb of the Atlantic Meridional Overturning Circulation.

Cover page of Spatial and temporal patterns in Hawai'i's intertidal: decadal changes in benthic community composition

Spatial and temporal patterns in Hawai'i's intertidal: decadal changes in benthic community composition

(2020)

Spatially broad and long-term monitoring studies are lacking in tropical intertidal systems yet are necessary to test predictions regarding community assembly. To fill this gap, we examined spatial and decadal temporal patterns in benthic community structure at rocky intertidal sites along the main islands of Hawai‘i. Quantitative community surveys done in 2017 across nine sites and five islands showed that organismal composition differed by site, substrate type, and island. Secondly, we leveraged an earlier dataset collected using the same methods and analyzed intertidal communities at five sites on three Hawaiian islands for temporal changes in organismal abundance and composition from 2006 and 2007 vs. 2016 and 2017. Overall community structure differed significantly across years and decades. Most decadal differences were site specific, such as the fivefold increase in turf algae at one site. Crustose coralline algae and Turbinaria ornata increased significantly across five sites; both are physically resilient algae and similar increases in their abundances have been observed in tropical systems worldwide. This increase in physically resilient macroalgal species is potentially caused by global drivers, such as rising temperatures and changing land uses. In conclusion, there is evidence that both local and regional factors contribute to structuring tropical intertidal communities.

Cover page of SPICE Mooring Data Report: Description and Quality Control

SPICE Mooring Data Report: Description and Quality Control

(2017)

The Solomon Sea is an important region for western Pacific water mass circulation, serving as the pathway that connects subtropical and equatorial waters. To observe this water mass transport, nine moorings were deployed in the exit channels of the Solomon Sea as an observational component of the Southwest Pacific Ocean Circulation and Climate Experiment (SPICE). This report details the deployment and recovery of the moored velocity, temperature, salinity, and pressure observations and the subsequent quality control procedures applied to the recovered observations. A summary of the quality controlled data is also given for each mooring.

Cover page of Catalog of Otoliths of Select Fishes from the California Current System

Catalog of Otoliths of Select Fishes from the California Current System

(2014)

This catalog contains images and features of sagittal otoliths from 47 species belonging to 17 families of fish found in the California Current System. We focus primarily on mesopelagic species, which are ecologically important yet are less studied than other species. For each sagitta, two images are presented, one with the sulcus up and another with the sulcus down. The linear relationship between standard length (SL) of a fish and major axis length (MAL) of its sagitta is presented for 24 species. Significant variability in SL is explained by MAL for 22 of the 24 species (n =5-61, R2 > 0.61, p < 0.05). Collection data and geometric shape features of all otoliths are also presented in tabular format. Our guide will assist researchers in the identification of sagittal otoliths of unknown origin and to estimate fish length from sagittal otolith size.

  • 1 supplemental file
Cover page of Hydrographic Atlas of the World Ocean Circulation Experiment (WOCE) Volume 4: Indian Ocean

Hydrographic Atlas of the World Ocean Circulation Experiment (WOCE) Volume 4: Indian Ocean

(2013)

The Hydrographic Programme of the international World Ocean Circulation Experiment (WOCE) was a comprehensive global hydrographic survey of physical and chemical properties, of unprecedented scope and quality, and represents the "state of the oceans" during the 1990s.   This PDF atlas is a copy of the published volume and contains full introductory text.  Web access: doi:10.21976/C61595

Cover page of Hydrographic Atlas of the World Ocean Circulation Experiment (WOCE) Volume 3: Atlantic Ocean

Hydrographic Atlas of the World Ocean Circulation Experiment (WOCE) Volume 3: Atlantic Ocean

(2011)

The Hydrographic Programme of the international World Ocean Circulation Experiment (WOCE) was a comprehensive global hydrographic survey of physical and chemical properties, of unprecedented scope and quality, and represents the "state of the oceans" during the 1990s.   This PDF atlas is a copy of the published volume and contains full introductory text.  Web access: doi.org/10.21976/C6RP4Z