نتایج جستجو برای: snow cover area
تعداد نتایج: 691239 فیلتر نتایج به سال:
A fully automated method uses Landsat Thematic Mapper data to map snow cover in the Sierra Nevada and make quantitative estimates of the fractional snow-covered area within each pixel. We model winter and spring reference scenes as linear mixtures of image end member spectra to produce the response variables for tree-based regression and classification models. Decision trees identify cloud cove...
How does snow’s anisotropic directional reflectance affect the mapping of snow properties from imaging spectrometer data? This sensitivity study applies two spectroscopy models to synthetic images of the spectral hemispherical–directional reflectance factor (HDRF) with prescribed snow-covered area and snow grain size. The MEMSCAG model determines both sub-pixel snow-covered area and the grain s...
The snow cover in lower mountain areas is often a very dynamic matter. For flood forecast, but also for continuous water balance modelling, a detailed knowledge of the snow cover, its temporal dynamics and current snow properties is essential. According to this, modelling of the snow cover is a constituent part of applied water balance models. To drive and calibrate the models, spatial measurem...
Most snow mold pathogens cause plant injury only under prolonged snow cover, so snow mold diseases are severe primarily in regions where snow cover persists for more than 100 days. Even within these regions, disease occurrence and severity varies greatly from year to year. When disease is severe, individual fungal colonies coalesce, resulting in substantial losses in plant stand (20). In other ...
The disproportionate amount of water runoff from mountains to surrounding arid and semiarid lands has generated much research in snow water equivalent (SWE) modeling. A primary input in SWE models is snow covered area (SCA) which is generally obtained via satellite imagery. Mixed pixels in alpine snow studies complicate SCA measurements and can reduce accuracy. A simple method was developed to ...
A technique of using satellite-derived data for constructing continuous snow characteristics fields for distributed snowmelt runoff simulation is presented. The satellite-derived data and the available ground-based meteorological measurements are incorporated in a physically based snowpack model. The snowpack model describes temporal changes of the snow depth, density and water equivalent (SWE)...
Snow cover in the Tibetan Plateau is highly variable in space and time and plays a key role in ecological processes of this cold-desert ecosystem. Resolution of passive microwave data is too low for regional-scale estimates of snow cover on the Tibetan Plateau, requiring an alternate data source. Optically derived snow indices allow for more accurate quantification of snow cover using higherres...
introduction: snowmelt runoff plays an important role in providing water and agricultural resources, especially in mountainous areas. there are different methods to simulate the process of snowmelt. inter alia, degree-day model, based on temperature-index is more cited. snowmelt runoff model is a conceptual hydrological model to simulate and predict the daily flow of rivers in the mountainous b...
Timely information on spatial distribution and temporal dynamics of snow cover in the pan-Arctic zone is needed, as snow cover plays an important role in climate, hydrology and ecological processes. Here we report estimates of snow cover in the pan-Arctic zone (north of 45‡N) at 1-km spatial resolution and at a 10-day temporal interval over the period of April 1998 to December 2001, using 10-da...
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