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Cover page of Calibration Methodology for the Scripps 13C/12C and 18O/16O stable Isotope program 1992-2018

Calibration Methodology for the Scripps 13C/12C and 18O/16O stable Isotope program 1992-2018


This report details calibration method for measurements of 13C/12C and 18O/16O ratios of atmospheric CO2 by the Scripps CO2 program from 1992-2018.  The method depends principally on repeat analysis of CO2 derived from a suite of high-pressure gas cylinders filled with compressed natural air pumped at La Jolla.  The first set of three cylinders were given isotopic assignments in 1994 based on comparisons with material artifacts NBS16, NBS17, and NBS19.  Six cylinders subsequently brought into service were assigned values by comparing directly or indirectly with this first set.  A tenth cylinder with natural CO2 in air was obtained from MPI Jena.  Aliquots of CO2 from these cylinders, which serve as secondary standards, were extracted into heat-sealed glass ampoules (“flame-off tubes”) before introduction into the mass spectrometer.  Some of these ampoules have been stored for many years before analysis, allowing long-term isotopic drift of the cylinders to be quantified.  All secondary standards contain natural levels of N2O.  The method corrects for any detected drift, while also applying corrections for N2O interference, for isobaric interferences (“Craig correction”) and for an inter-lab offset identified in early comparisons with the isotope lab at the University of Groningen.  The Jena cylinder was found to be drifting upwards in δ18O at a rate of +0.10 ‰ per decade.  Five of the other nine cylinders were found to be drifting downwards in δ18O, δ13C, or both, at rates of up to -0.11‰ per decade.  The secondary standards were applied uniformly across a transition to a new mass spectrometer in 2000, thereby establishing continuity across this transition.  Results are presented also for instrumental precision based on replicate analyses of standards.  Drift-corrected analyses of the Jena cylinder establishes offsets of +0.037 ‰ in δ13C and +0.041 ‰ in δ18O between the Scripps and JRAS isotopic scales (Scripps more positive).

Cover page of On the Natural Geography of North San Diego County

On the Natural Geography of North San Diego County


As a consequence of the prevailing geographic diversity, the county has an extraordinary variety of plants and animals. It is an internationally recognized "biodiversity hot spot" and has very few equals in that regard, in all of North America or elsewhere on our planet.

Cover page of On “CHAPARRAL” versus “COASTAL SAGE SCRUB” in San Diego County

On “CHAPARRAL” versus “COASTAL SAGE SCRUB” in San Diego County


The County of San Diego has both "Coastal Sage Scrub" and "Chaparral" in abundance. In fact, these two ecosystems cover most of the ground in the county, albeit with many different types. Many of the plants involved in the two systems are deceptively similar, although they quite commonly belong to different species. Naturally, one would like to know how to keep the two communities apart. The criteria, evidently, are plant species distributions. These have been and are being mapped by various methods, including field work by expert observers, collections of specimens in museum repositories, and the study of air photos and satellite images.

Cover page of Hans E. Suess (1909-1993): Radiocarbon, Sun and Climate Pioneer

Hans E. Suess (1909-1993): Radiocarbon, Sun and Climate Pioneer


Hans Suess was interested in the question of how the sun’s activity changes through time, and whether the variations in activity can be recognized in climate proxy records.

Cover page of Stable Isotope Protocols: Sampling and Sample Processing

Stable Isotope Protocols: Sampling and Sample Processing


These protocols are designed to provide the information needed by researchers or managers to conduct natural abundance stable isotopic analyses of marsh food sources (suspended particulate organic matter [SPOM], vascular plants, benthic microalgae[BMI], benthic macroalgae) and sediments, as well as common invertebrate and vertebrate consumers (snails, mussels, crabs, macroinfauna and fish). A list of supplies required to carry out the protocols is given in Table A-1.

Cover page of SPOTL: Some Programs for Ocean-Tide Loading

SPOTL: Some Programs for Ocean-Tide Loading


The increasing precision of geodetic measurements has made the effects of loading by ocean tides(or other sources) important to a wider range of researchers than just the earth-tide community.Computing such loading effects has, however, remained a rather specialized activity. This collectionof programs aims to make it easy to compute load tides, or, with slight modifications, the effects ofother loads.Given that the most accurate representations of the ocean tides require both global and regionalmodels, my aim has also been to make it easy to combine different tidal models, and to use differentEarth models (though the method is restricted to spherically symmetric ones). Especially for theglobal ocean tide there are many models available; this package provides a set of current modelsfound using different methods.The package also includes programs to allow the computed loads (or the ocean tide) to be convertedinto harmonic constants, and to compute the tide in the time domain from these constants. Forcompleteness a program for direct computation of the body tides is included; while its accuracy isnot as high as that of some others (for example Merriam (1992)), it should be more than adequatefor representing any but (perhaps) gravity-tide measurements with low-noise instruments.This package can actually be used to find the surface effects of any load, so long as these effects arefrom elastic deformation, which is appropriate for any load with a time constant shorter than years:for example, changing reservoir water levels, seasonal groundwater changes, and non-tidal oceanloading.

Cover page of Miklankovitch Theory - Hits and Misses

Miklankovitch Theory - Hits and Misses


Milankovitch Theory has become an important tool in geologic practice andthought, and is sufficiently conspicuous to provide a rewarding target for criticism.The chief problem arising has to do with the prominence of a cycle near 100,000years, whose origin is not clear. Most practitioners, presumably, would accept aclose relationship of that cycle to precession of the equinoxes (that is, cyclicchanges in seasonality), along with dynamical properties of the system thatenhance the amplitude of the 100-kyr cycle at the expense of others. In anycase, Milankovitch Theory has proved useful, both for age assignments and forstimulating thought about relationships between climate change andsedimentation, as is readily evident from the relevant literature. It would bedifficult to replace. Neither does it seem desirable to do so: the chief problemnoted in regard of the theory (the 100-kyr problem) is not necessarily a part of thetheory, which is concerned with change rather than with condition. The 100-kyrcycle is linked to condition. The problem raised by critics seems to be the timescale of integration of change, a problem not addressed in Milankovitch Theory.A necessity for additional processes and mechanisms not considered inMilankovitch Theory cannot be excluded.

Cover page of References Cited in “Ocean, Reflections on a Century of Exploration” (University of California Press, 2009)

References Cited in “Ocean, Reflections on a Century of Exploration” (University of California Press, 2009)


In the following are listed the various references used in a treatise on ocean exploration, recently published by the University of California Press (Berger, W.H., 2009. Ocean – Reflections on a Century of Exploration. UC Press, Berkeley 519pp.; with contributions by E.N. Shor). The list is alphabetical (unlike in the volume) and is suited for electronic searching and for downloading. The references were assembled to reflect ocean research in the 20th century. There is some bias toward marine geology and ecology, and toward work in these fields at the U.S. West Coast. Also, there is some emphasis on research at Scripps Institution of Oceanography (which celebrated the centennial of its founding in 2003). Historical aspects owe much to numerous contributions by E.N. Shor. For topics that were not represented in my collection of reprints and books, I used various symposia and encyclopedias. One that proved especially useful is the 6-volume encyclopedia on the ocean edited by Steele et al. (2001). Some relevant references only list the name of the contributor and the treatise. A few references are incomplete in the original book and have been completed for the present list. The total number of references is 889.