Engineering topics

Broecker, Wallace S.

Publications and source records attributed to Broecker, Wallace S..

8 records

NASA NTRS1998

Antiphasing Between Rainfall in Africa's Rift Valley and North America's Great Basin

The beginning of the Bolling-Allerod warm period is marked in Greenland ice by an abrupt rise in (Delta)O-18, an abrupt drop in dust rain, and an abrupt increase in atmospheric methane content. The surface waters in the Norwegian Sea underwent a simultaneous abrupt warming. At about this time, a major change in the pattern of global rainfall occurred. Lake Victoria (latitude 0deg), which prior to this time was dry, was rejuvenated. The Red Sea, which prior to this time was hypersaline, freshened. Lake Lahontan, which prior to this time had achieved its largest size, desiccated. Whereas the chronologic support for the abruptness of the hydrologic changes is firm only for the Red Sea, in keeping with evidence obtained well away from the nor-them Atlantic in the Santa Barbara basin and the Cariaco Trench, the onset and end of the millennial-duration climate events were globally abrupt. If so, the proposed linkage between the size of African closed basin lakes and insolation cycles must be reexamined.

Broecker, Wallace S.↗

NASA NTRS1997

Summer Research Internships at Biosphere 2 Center

Through the support of NASA's Mission to Planet Earth, Biosphere 2 Center hosted 11 research interns for 6 to 8 weeks each during the summer of 1997. In addition, we were able to offer scholarships to 14 students for Columbia University summer field courses. These two types of programs engaged students in much of the range of activity of practicing Earth Scientists, with an emphasis on the collection and analysis of data in both the field and the laboratory. Research interns and students in the field courses also played an important part in the design and evolution of their research projects. In addition to laboratory and field research, students participated in weekly research seminars by resident and visiting scientists. Research interns were exposed to the geology and ecology of the region via short field trips to the Arizona Sonora Desert Museum, Mount Lemmon, Aravaipa Canyon and the Gulf of California, while field course students were exposed to laboratory-based research via intern-led hands-on demonstrations of their work. All students made oral and written presentations of their work during the summer, and two of the research interns have applied to present their results at the National Conference on Undergraduate Research in Maryland in April, 1998.

Broecker, Wallace S.↗

NASA NTRS1994

Atmospheric, Climatic, and Environmental Research

The climate and atmospheric modeling project involves analysis of basic climate processes, with special emphasis on studies of the atmospheric CO2 and H2O source/sink budgets and studies of the climatic role Of CO2, trace gases and aerosols. These studies are carried out, based in part on use of simplified climate models and climate process models developed at GISS. The principal models currently employed are a variable resolution 3-D general circulation model (GCM), and an associated "tracer" model which simulates the advection of trace constituents using the winds generated by the GCM.

Broecker, Wallace S.↗

NASA NTRS1992

Atmospheric, climatic and environmental research

Work performed on the three tasks during the report period is summarized. The climate and atmospheric modeling studies included work on climate model development and applications, paleoclimate studies, climate change applications, and SAGE II. Climate applications of Earth and planetary observations included studies on cloud climatology and planetary studies. Studies on the chemistry of the Earth and the environment are briefly described. Publications based on the above research are listed; two of these papers are included in the appendices.

Broecker, Wallace S.↗

NASA NTRS1992

Dynamic constraints on CO2 uptake by an iron-fertilized Antarctic

The topics covered include the following: tracer distribution and dynamics in the Antarctic Ocean; a model of Antarctic and Non-Antarctic Oceans; effects on an anthropogenically affected atmosphere; effects of seasonal iron fertilization; and implications of the South Atlantic Ventilation Experiment C-14 results.

Peng, Tsung-Hung↗

NASA NTRS1989

The global geochemistry of bomb-produced tritium - General circulation model compared to available observations and traditional interpretations

Observational evidence suggests that of the tritium produced during nuclear bomb tests that has already reached the ocean, more than twice as much arrived through vapor impact as through precipitation. In the present study, the Goddard Institute for Space Studies 8 x 10 deg atmospheric general circulation model is used to simulate tritium transport from the upper atmosphere to the ocean. The simulation indicates that tritium delivery to the ocean via vapor impact is about equal to that via precipitation. The model result is relatively insensitive to several imposed changes in tritium source location, in model parameterizations, and in model resolution. Possible reasons for the discrepancy are explored.

Koster, Randal D.↗

NASA NTRS1988

Tracer water transport and subgrid precipitation variation within atmospheric general circulation models

A capability is developed for monitoring tracer water movement in the three-dimensional Goddard Institute for Space Science Atmospheric General Circulation Model (GCM). A typical experiment with the tracer water model follows water evaporating from selected grid squares and determines where this water first returns to the Earth's surface as precipitation or condensate, thereby providing information on the lateral scales of hydrological transport in the GCM. Through a comparison of model results with observations in nature, inferences can be drawn concerning real world water transport. Tests of the tracer water model include a comparison of simulated and observed vertically-integrated vapor flux fields and simulations of atomic tritium transport from the stratosphere to the oceans. The inter-annual variability of the tracer water model results is also examined.

Koster, Randal D.↗

NASA NTRS1987

Gas exchange on Mono Lake and Crowley Lake, California

Gas exchange coefficients (k) have been determined for freshwater Crowley Lake and saline Mono Lake through the use of a man-made purposefully injected gas, SF6. The concentration decreased from an initial value of 40 to 4 pmol/L for Mono Lake and from 20 to 1 pmol/L for Crowley lake over a period of 6 wks. Wind-speed (u) records from anemometers on the shore of each lake made it possible to determine the relationship between k and u. The average u and k values for the experiment were identical for the two lakes, despite the large chemical differences. It is estimated that, for the u values observed over Mono Lake from July to December 1984, the exchange of CO2 occurred 2.5 times faster than without chemical enhancement. This is a factor of 4 lower than needed to explain the high invasion rate of C-14 produced by nuclear bomb tests.

Wanninkhof, Rik↗