منابع مشابه
Declining Mountain Snowpack in Western North America*
JANUARY 2005 AMERICAN METEOROLOGICAL SOCIETY | ountain snowpack in western North America is a key component of the hydrologic cycle, storing water from the winter (when most precipitation falls) and releasing it in spring and early summer, when economic, environmental, and recreational demands for water throughout the West are frequently greatest. In most river basins of the West, especially in...
متن کاملVariability and trends in Mountain Snowpack in Western North America
Snow course and SNOTEL measurements of spring snowpack, corroborated by a physically-based hydrologic model, are examined here for climate-driven fluctuations and trends during the period 1916-2002. Much of the mountain West has experienced declines in spring snowpack, especially since mid-century, and despite increases in winter precipitation in many places. Analysis and modeling shows that cl...
متن کاملNovel Serotype of Bluetongue Virus, Western North America
To the Editor: Bluetongue is an arboviral disease of domestic and wild ruminants characterized by vascular injury that produces widespread edema and tissue necrosis (1). Bluetongue virus (BTV), the causative agent of bluetongue, is the prototype virus of the genus Orbivirus in the family Reoviridae (2). BTV occurs throughout temperate and tropical areas of the world coincident with the distribu...
متن کاملPerformance of salmon fishery portfolios across western North America
Quantifying the variability in the delivery of ecosystem services across the landscape can be used to set appropriate management targets, evaluate resilience and target conservation efforts. Ecosystem functions and services may exhibit portfolio-type dynamics, whereby diversity within lower levels promotes stability at more aggregated levels. Portfolio theory provides a framework to characteriz...
متن کاملPhylogeography of chestnut-backed chickadees in western North America
North American chickadees and titmice are believed to be descendents of Eurasian lineages that crossed the Bering land bridge in the late Pliocene 3.5 to 4 million years ago (Gill et al. 2005; see also Chapters 1 and 2). The North American chickadees are divided into two groups based on phenotypic differences (references in Gill et al. 1989). The black-capped group contains four species: black-...
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ژورنال
عنوان ژورنال: Proceedings of the American Academy of Arts and Sciences
سال: 1917
ISSN: 0199-9818
DOI: 10.2307/20025695