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for other basins, has focused primarily on temperature minima and nighttime temperature inversions. Sauberer and Dirmhirn, however, included two temperature soundings in their 1954 paper that were made partway through the postsunrise temperature inversion breakup period. These soundings, conducted on an early March morning with snow cover, showed warming progressed downward into the basin from aloft during the inversion destruction period. As we will see, our data collected during a non-snow-covered
for other basins, has focused primarily on temperature minima and nighttime temperature inversions. Sauberer and Dirmhirn, however, included two temperature soundings in their 1954 paper that were made partway through the postsunrise temperature inversion breakup period. These soundings, conducted on an early March morning with snow cover, showed warming progressed downward into the basin from aloft during the inversion destruction period. As we will see, our data collected during a non-snow-covered
specified timeof year. The tundra included spring snowmelt and the grassland incorporated snow accumulation. The sensitivityexperiments included varying the soil texture from a coarse texture typical of sand through a medium texturetypical of loam to a fine texture typical of clay. The sensitivity of the formulation to the specified total andupper soil column depth and the response to altering the parameterization of the soil albedo dependence uponsoil wetness and snow-cover were also examined. The
specified timeof year. The tundra included spring snowmelt and the grassland incorporated snow accumulation. The sensitivityexperiments included varying the soil texture from a coarse texture typical of sand through a medium texturetypical of loam to a fine texture typical of clay. The sensitivity of the formulation to the specified total andupper soil column depth and the response to altering the parameterization of the soil albedo dependence uponsoil wetness and snow-cover were also examined. The
function of cloud droplet size. However, in the polar regions, the surface is covered by snow/ice most of the time throughout the year, and visible solar radiation in AVHRR channel 1 (0.58–0.68 μ m) that is reflected by clouds over a bright snow/ice surface is not as sensitive to the cloud optical depth as over a dark surface. So, it is difficult to use AVHRR channel 1 for the retrieval of τ over snow/ice surfaces. The reflectance in channel 2 (0.725–1.10 μ m) is more sensitive to the cloud optical
function of cloud droplet size. However, in the polar regions, the surface is covered by snow/ice most of the time throughout the year, and visible solar radiation in AVHRR channel 1 (0.58–0.68 μ m) that is reflected by clouds over a bright snow/ice surface is not as sensitive to the cloud optical depth as over a dark surface. So, it is difficult to use AVHRR channel 1 for the retrieval of τ over snow/ice surfaces. The reflectance in channel 2 (0.725–1.10 μ m) is more sensitive to the cloud optical
mainly used for melting of the snow cover. For the hill station the heat fluxe~ are generally smaller. The only source is the radiation balancecal cm'~), wh/ch is only 40% of the value found for the valley station. The latent heat flux is much smaller(- 19 cal cm"I), a~d the surface temperature on the hill is higher. The sensible heat flux is slightly negative(-2 cal cm~), meaning that the air will be warmed by the surface only slightly for an average day overa year in contrast to the valley
mainly used for melting of the snow cover. For the hill station the heat fluxe~ are generally smaller. The only source is the radiation balancecal cm'~), wh/ch is only 40% of the value found for the valley station. The latent heat flux is much smaller(- 19 cal cm"I), a~d the surface temperature on the hill is higher. The sensible heat flux is slightly negative(-2 cal cm~), meaning that the air will be warmed by the surface only slightly for an average day overa year in contrast to the valley
assumption is made that the average daily air temperature is representative of the temperature of the snow surface. The snow depth ( Z s ) gives the thickness of the first layer in the snow/soil system ( Fig. 1 ). In the absence of snow cover, the air temperature is assumed to equal the temperature at the upper surface of a 1.0 × 10 −3 -m laminar layer, the thermal properties of which are characteristic of still air. To avoid the assumption of equality between the air and soil surface temperature, the
assumption is made that the average daily air temperature is representative of the temperature of the snow surface. The snow depth ( Z s ) gives the thickness of the first layer in the snow/soil system ( Fig. 1 ). In the absence of snow cover, the air temperature is assumed to equal the temperature at the upper surface of a 1.0 × 10 −3 -m laminar layer, the thermal properties of which are characteristic of still air. To avoid the assumption of equality between the air and soil surface temperature, the
again occur over regions classified by the USGS as having wooded tundra. The standard deviations of R 2 values are the largest, indicating uncertainty, over water bodies and wooded tundra. The R 2 values remain higher than 0.5 over the well-vegetated land uses mentioned above. The lower R 2 values over wooded tundra suggest that frozen surface soil and snow cover may disturb the relationships between the NCI and observed cloud indices. Figure 6 shows that the weakest relationships for both
again occur over regions classified by the USGS as having wooded tundra. The standard deviations of R 2 values are the largest, indicating uncertainty, over water bodies and wooded tundra. The R 2 values remain higher than 0.5 over the well-vegetated land uses mentioned above. The lower R 2 values over wooded tundra suggest that frozen surface soil and snow cover may disturb the relationships between the NCI and observed cloud indices. Figure 6 shows that the weakest relationships for both
present study, by employing a soil model that makes use of daily routine meteorological data, the daily and seasonal variation of heat and water balances in different climatic regions have been simulated. The following themes are investigated: the variations in the heat balance and the soil-water content under different climatic conditions, such as in moist, semiarid, and arid regions; the relationship between soil type and water balance;and the effect of snow cover on the heat and water balances. The
present study, by employing a soil model that makes use of daily routine meteorological data, the daily and seasonal variation of heat and water balances in different climatic regions have been simulated. The following themes are investigated: the variations in the heat balance and the soil-water content under different climatic conditions, such as in moist, semiarid, and arid regions; the relationship between soil type and water balance;and the effect of snow cover on the heat and water balances. The
help identify surface and cloud types. Cirrus, cumulus, and stratocumulus clouds have significantly different macro- and microtextural characteristics whichcan be quantitatively measured (Welch et al. 1988; Kuoet al. 1988). Features such as cold, bumpy cloud tops,cloud shadows on the snow, illumination of cloud sides,and cracks and leads in the sea ice can aid the humanobserver in distinguishing cloud cover from sea ice andsnow in satellite imagery (Kukla 1984; Welch et al.1989). Ebert (1987) used
help identify surface and cloud types. Cirrus, cumulus, and stratocumulus clouds have significantly different macro- and microtextural characteristics whichcan be quantitatively measured (Welch et al. 1988; Kuoet al. 1988). Features such as cold, bumpy cloud tops,cloud shadows on the snow, illumination of cloud sides,and cracks and leads in the sea ice can aid the humanobserver in distinguishing cloud cover from sea ice andsnow in satellite imagery (Kukla 1984; Welch et al.1989). Ebert (1987) used
-yearperiod between 1962 and 1966. Data on incoming shortwave radiation, albedo, incoming longwave radiation,and net total radiation are summarized in the form of monthly and annual averages. Due to the prevalenceof summer clouds, incident shortwave radiation (Q) reaches a peak in early ~une with maximum flux valuesin excess of 50 mW cm-a. Increasing cloud cover throughout the snow-free period results in a distributionfor Q which is asymmetric about the summer solstice. Atmospheric transmissivity averages vary
-yearperiod between 1962 and 1966. Data on incoming shortwave radiation, albedo, incoming longwave radiation,and net total radiation are summarized in the form of monthly and annual averages. Due to the prevalenceof summer clouds, incident shortwave radiation (Q) reaches a peak in early ~une with maximum flux valuesin excess of 50 mW cm-a. Increasing cloud cover throughout the snow-free period results in a distributionfor Q which is asymmetric about the summer solstice. Atmospheric transmissivity averages vary
. Retrieved high refiectivities over land surface at 90 GHz and 183 GHzare presumably related to snow cover on the ground. This suggests that radiometric measurements at thesefrequencies could be used to map snow at high-latitude regions.1. Introduction The radiometric measurements near the strong watervapor absorption line of 183.3 GHz have in the pastbeen used mostly for retrieval of atmospheric watervapor profiles (Schaefer and Wilbeit 1979; Rosenkranzet at. 1982; Kakar 1983; W,?ng et ai. 1983
. Retrieved high refiectivities over land surface at 90 GHz and 183 GHzare presumably related to snow cover on the ground. This suggests that radiometric measurements at thesefrequencies could be used to map snow at high-latitude regions.1. Introduction The radiometric measurements near the strong watervapor absorption line of 183.3 GHz have in the pastbeen used mostly for retrieval of atmospheric watervapor profiles (Schaefer and Wilbeit 1979; Rosenkranzet at. 1982; Kakar 1983; W,?ng et ai. 1983
