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At least 415 records · Page 23Linked to original sources

The interplay between transpiration and Runoff formulations in land surface schemes used with atmospheric models

The Project for Intercomparison of Land-surface Parameterization Schemes (PILPS) has shown that different land surface models (LSMs) driven by the same meteorological forcing can produce markedly different surface energy and water budgets, even when certain critical aspects of the LSMs (vegetation cover, albedo, turbulent drag coefficient, and snowcover) are carefully controlled. To help explain these differences, the authors devised a monthly water balance model that successfully reproduces the annual and seasonal water balances of the different PILPS schemes. Analysis of this model leads to the identification of two quantities that characterize an LSM's formulation of soil water balance dynamics: 1) the efficiency of the soil's evaporation sink integrated over the active soil moisture range, and 2) the fraction of this range over which runoff is generated. Regardless of the LSM's complexity, the combination of these two derived parameters with rates of interception loss, potential evaporation, and precipitation provides a reasonable estimate for the LSM's simulated annual water balance. The two derived parameters shed light on how evaporation and runoff formulations interact in an LSM, and the analysis as a whole underscores the need for compatibility in these formulations.

Journal of Climate

Coastal plain pond water quality and mercury contend of biota of the Long Island Central Pine Barrens and Mashomack Preserve: Effects of atmospheric deposition and human development

Pine barrens are considered an imperiled ecosystem in the northeastern U.S. The Suffolk County Pine Barrens, once the second largest in the Northeast, were substantially reduced and fragmented by development during the 20th century. The coastal plain ponds being considered in this study occur in central Suffolk County within the Long Island Central Pine Barrens region. This highly unique natural environment, embedded with forests and woodlands, resulted from its glacial origins and a land use history that predates European colonization. Included in this study was The Nature Conservancy’s Mashomack Preserve, located on Shelter Island between Peconic Bay and Gardiner’s Bay. There are no freshwater ponds in the Mashomack Preserve, but this area was included with the Central Pine Barrens investigation, because Shelter Island has a similar geologic and land-use history that has resulted in a similarly unique low-nutrient forest and woodland ecosystem with extremely coarse-textured soils.

New York

Patterns of orographic uplift in the Sierra Nevada and their relationship to upper-level atmospheric circulation

We examine monthly and seasonal patterns of precipitation across various elevations of the eastern Central Valley of California and the Sierra Nevada. A measure of the strength of the orographic effect called the “precipitation ratio” is calculated, and we separate months into four groups based on being wet or dry and having low or high precipitation ratios. Using monthly maps of mean 700-mb height anomalies, we describe the northern hemisphere mid-tropospheric circulation patterns associated with each of the four groups. Wet months are associated with negative height anomalies over the eastern Pacific, as expected. However, the orientation of the trough is different for years with high and low precipitation ratios. Wet months with high ratios typically have circulation patterns factoring a west-southwest to east-northeast storm track from around the Hawaiian Islands to the Pacific Northwest of the United States. Wet months with low precipitation ratios are associated with a trough centered near the Aleutians and a northwest to southeast storm track. Dry months are marked by anticyclones in the Pacific, but this feature is more localized to the eastern Pacific for months with low precipitation ratios than for those with high ratios. Using precipitation gauge and snow course data from the American River and Truckee-Tahoe basins, we determined that the strength of the orographic effect on a seasonal basis is spatially coherent at low and high elevations and on opposite sides of the Sierra Nevada crestline.

California

Solubility of cryolite at 25° C and 1 atmosphere pressure

For natural cryolite from Greenland the activity product for the reaction (in water), Na 3 Al F 6 c --> 3Na + + Al 3+ + 6F - , was found to be 10 -34.3 +/- 0.1 . This is in good agreement with earlier work in which equilibrium was approached from supersaturation.

Journal of Research of the U.S. Geological Survey

Correlation between atmospheric precipitation and recent explosions at Mount St. Helens, Washington

Scientists attribute the recent small explosion-like seismic signals at Mount St. Helens to either the geyser-like flashing of superheated groundwater to steam or the release of magmatic gas from the cooling magma system, or both. The contribution of magmaic gas in these events is not currently known. If meteoric water from rain or melting snow is the source, however, we might expect these events to occur most frequently during the rainy season, perhaps even during or immediately following individual storms.

Washington

Waste isolation and contaminant migration - Tools and techniques for monitoring the saturated zone-unsaturated zone-plant-atmosphere continuum

In 1976 the U.S. Geological Survey (USGS) began studies of unsaturated zone hydrology next to the Nation’s first commercial disposal facility for low-level radioactive waste (LLRW) near Beatty, NV. Recognizing the need for long-term data collection, the USGS in 1983 established research management areas in the vicinity of the waste-burial facility through agreements with the Bureau of Land Management and the State of Nevada. Within this framework, the Amargosa Desert Research Site (ADRS; http://nevada.usgs.gov/adrs/) is serving as a field laboratory for the sustained study of water-, gas-, and contaminant-transport processes, and the development of models and methods to characterize flow and transport. The research is built on multiple lines of data that include: micrometeorology; evapotranspiration; plant metrics; soil and sediment properties; unsaturated-zone moisture, temperature, and gas composition; geology and geophysics; and groundwater. Contaminant data include tritium, radiocarbon, volatile-organic compounds (VOCs), and elemental mercury. Presented here is a summary of monitoring tools and techniques that are being applied in studies of waste isolation and contaminant migration.

Conference Paper