Characterization of aerosol optical properties, such as aerosol optical depth, Angstrom exponent, and volume size distribution at the semiarid site of Tombstone Arizona (31823VN, 110805VW, 1408 m) will be presented for one annual cycle. In this region, extensive observations of selected optical parameters such as aerosol optical depth (AOD) have been made in the past and reported on in the lite...

[1] In recent years, a number of relatively high resolution seismic tomography models for the uppermost mantle underneath the western United States have been published, and vigorous debate has ensued about their tectonic interpretation. I present a straightforward, yet quantitative, comparison between models in order to help establish a framework for geodynamic interpretation, and to help judge...

United States ERainstorm Member, Johnnie Formation (34)^ but chose to equate it with a postulated Gaskiers-related dC excursion from circa 580 Ma (35). Instead, our data indicate that this globally correlated negative dC excursion is not related to any known glaciation (36). The duration of this excursion is unconstrained; however, given that it is captured within over 100 m of section in Oman ...

The water resources of the western United States depend heavily on snowpack to store part of the wintertime precipitation into the drier summer months. A well-documented shift toward earlier runoff in recent decades has been attributed to 1) more precipitation falling as rain instead of snow and 2) earlier snowmelt. The present study addresses the former, documenting a regional trend toward sma...

[1] Persistent, widespread wet conditions in the western United States in the early twentieth century have been noted in a number of studies. Here, we investigate the character of this pluvial, which covered a roughly 9-state region and lasted about 13 years. Paleoclimatic data used to evaluate the period in a long-term context indicate that the twentiethcentury pluvial is an extremely rare eve...

We examine 20-yr data sets of seismic activity from 10 volcanic areas in the western United States for annual periodic signals (seasonality), focusing on large calderas (Long Valley caldera and Yellowstone) and stratovolcanoes (Cascade Range). We apply several statistical methods to test for seasonality in the seismic catalogs. In 4 of the 10 regions, statistically significant seasonal modulati...

within the national forests of the west, is one of the most contentious natural resource issues in the US today. One recent response to the controversy is the Healthy Forests Restoration Act (HFRA) of 2003 (Public Law 108-V148). This law has potentially profound consequences for forests and their biodiversity and must therefore be implemented on the basis of the best scientific information and ...

PURPOSE To determine the incidence of exercise-associated hyponatremia (EAH), the associated biochemical measurements and risk factors for EAH, and whether there is an association between postrace blood sodium concentration ([Na+]) and changes in body mass among participants in the 2009 Western States Endurance Run, a 161-km mountain trail run. METHODS Change in body mass, postrace [Na+], and...

The relative role of block versus continuum deformation of continental lithosphere is a current subject of debate. Continuous deformation is suggested by distributed seismicity at continental plate margins and by cumulative seismic moment sums which yield slip estimates that are less than estimates from plate motion studies. In contrast, block models are favored by geologic studies of displacem...

In this article we develop a simulation model for estimating the economic efficiency of fuel treatments and apply it to two sagebrush ecosystems in the Great Basin of the western United States: Wyoming Sagebrush Steppe and Mountain Big Sagebrush. These two ecosystems face the two most prominent resource management concerns in sagebrush ecosystems relative to wildfire: annual grass invasion and ...