نتایج جستجو برای: snow cover area
تعداد نتایج: 691239 فیلتر نتایج به سال:
[1] We used daily remotely sensed fractional snow-covered area (SCA) at 500 m resolution to estimate snow water equivalent (SWE) across the Upper Merced and Tuolumne River basins of the Sierra Nevada of California for 2004 (dry and warm) and 2005 (wet and cool). From 1800 to 3900 m, each successively higher 300 m elevation band consistently melts out 2–3 weeks later than the one below it. We co...
1 Throughout much of the latter half of the 20th century, the dominant mode of North2 ern Hemisphere (NH) extratropical wintertime circulation variability−the Arctic Oscillation 3 (AO)−exhibited a positive trend, with decreasing high-latitude sea-level pressure (SLP) and 4 increasing mid-latitude SLP. General circulation models (GCMs) show this trend is related 5 to several factors, including N...
In many instances, snow cover and duration are a major controlling factor on a range of environmental systems in mountain regions. When assessing the impacts of climatic change on mountain ecosystems and river basins whose origin lie in the Alps, one of the key controls on such systems will reside in changes in snow amount and duration. At present, regional climate models or statistical downsca...
Arctic ecosystems have been afflicted by vast changes in recent decades. Changes in temperature, as well as precipitation, are having an impact on snow cover, vegetation productivity and coverage, vegetation seasonality, surface albedo, and permafrost dynamics. The coupled climate-vegetation change in the arctic is thought to be a positive feedback in the Earth system, which can potentially fur...
Seasonal snow covers large land areas of the Earth. Information about the snow extent in these regions is important for climate studies and water resource management. A linear spectral mixture model for snow-covered forests (the SnowFor model) has previously been developed for flat terrain. The SnowFor model includes reflectance components for snow, trees and snow-free ground. In this paper, th...
The Arctic icescape is rapidly transforming from a thicker multiyear ice cover to a thinner and largely seasonal first-year ice cover with significant consequences for Arctic primary production. One critical challenge is to understand how productivity will change within the next decades. Recent studies have reported extensive phytoplankton blooms beneath ponded sea ice during summer, indicating...
The feasibility of retrieving changes in the depth of snow cover by means of the LISA (LInear SAR) Ground-Based Synthetic Aperture Radar system has been investigated. The LISA instrument consists of a computer-controlled sledge moving along a linear axis 5 m long, a set of transmit and receive antennas, a network analyzer, and a C-Band amplifier. All the equipment is installed inside a temperat...
The Himalayas are presently holding the largest ice masses outside the polar regions and thus (temporarily) store important freshwater resources. In contrast to the contemplation of glaciers, the role of runoff from snow cover has received comparably little attention in the past, although (i) its contribution is thought to be at least equally or even more important than that of ice melt in many...
Remote sensing data can provide images of snow covered areas and, therefore, it is possible to follow the time evolution of snow melting spatial patterns with increasing spatial and temporal resolution. Snow cover patterns are dominated by the complex interplay of topography, radiation forcings and atmospheric turbulent transfer processes. The snow cover evolution in an alpine basin in Trentino...
Climate change effects on snow cover and thermic regime in alpine tundra might lead to a longer growing season, but could also increase risks to plants from spring frost events. Alpine snowbeds, i.e. alpine tundra from late snowmelt sites, might be particularly susceptible to such climatic changes. Snowbed communities were grown in large monoliths for two consecutive years, under different mani...
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