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Edward A. Boyle 《Geochimica et cosmochimica acta》2005,69(21):5165-5166
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Summary Snow has been studied widely in hydrology for many decades whereas recent meteorological interest in snow is caused by increased
emphasis on high latitudes and wintertime in climate-change research as well as by the need to improve weather-forecast models
during these conditions. Ground-based measurements of snow properties are needed both to improve understanding of surface-atmosphere
exchange processes and to provide ground truth to new remote-sensing algorithms. This justifies a review of techniques to
measure snow in combination with establishment of criteria for the suitability of the methods for process studies. This review
assesses the state-of-art in ground-based snow-measurement techniques in the end of the 1990s in view of their accuracy, time
resolution, possibility to automate, practicality and suitability in different terrain. Methods for snow-pack water equivalent,
depth, density, growth, quality, liquid-water content and water leaving the snow pack are reviewed. Synoptic snow measurements
in Fennoscandian countries are widely varying and there is no single standard on which process-related studies can build.
A long-term, continuous monitoring of mass and energy properties of a snow cover requires a combination of point-measurement
techniques. Areally representative values of snow properties can be achieved through a combination of automatically collected
point data with repeated manual, areally covering measurements, remote-sensing data and digital elevation models, preferably
in a GIS framework.
Received August 27, 1999 相似文献
179.
R. A. Treidl 《Boundary-Layer Meteorology》1970,1(2):155-168
When relatively warm, moist air moves over a snow surface, sensible heat and moisture are extracted from its lower layers and used to melt the snow. The depth of the cooled layer depends on horizontal wind speeds and the presence of high vertical wind shear. The mechanism for air mass modification appears to be turbulent mixing. 相似文献
180.
In the Western Lake Baikal, recent Baikal Rift's tectonics control the topography, seismicity, climate, geomorphology, and economy. Scarps, facets, structural terraces, horsts and grabens, and trapezoid valleys can be clearly observed. They have been generated by the recent tectonic movements along the faults and represent a serious geologic hazard. The specific geological conditions predetermine a unique variety of landscapes. Thus, the main type of the economy is tourism. However, unorganized tourism leads to the degradation of the unique landscapes. It increases risk and requires disaster management. Three criteria has been used for risk assessment: (1) degree of geologic hazard; (2) degree of landscape degradation; and (3) degree of the economy's vitality. The high ecological significance and low stability to antropogeneous pressure are typical for landscapes of the Western Lake Baikal. Thus, some special activities of disaster management should be implemented based on our investigation. 相似文献