Passive and Active Microwave Studies of Wet Snowpack Properties

Abstract

Microwave signatures have been found to be related to variations in snow conditions found on the earth's surface. Most of these observations have been obtained by passive microwave radiometry. In general, inverse relationships between microwave brightness temperature (TB) and snow depth were observed for dry snowpacks. The results from truck-mounted scatterometers indicated that the backscattering cross sections from snowpacks increased with snow depths, also in dry snow conditions. The reported aircraft mission was the first trial in which simultaneous active and passive microwave measurements were made over a wet snowpack. The test site was located in the Colorado Rocky Mountains. The results from this experiment suggest that microwave techniques using both radiometers and scatterometers may be useful in determining snow water equivalent even when the snowpack is wet.

Radar measurements of snow: experiment and analysis

“…If the incremental increase is known, an accurate estimate of may be obtained by inverting (14). The incremental increase itself may really only be known if the density of the snow is also known, so that the base contribution to represented by the dry snow component may be accounted for.…”

“…There exists already numerous experimental studies of snow in the literature, both at microwave frequencies [10]- [14], and at millimeter-wave frequencies [15], [16]. Using such experimental data for the purpose of evaluation of models is very difficult because of the need to carefully characterize the target.…”

Remote sensing of snow depth and snow water equivalent

“…Empirical techniques based on the inverse relationship between brightness temperature and snow depth were the first to be proposed in the literature (e.g., Chang et al, 1978Chang et al, , 1979Chang et al, , 1986Chang et al, , 1989Chang et al, , 1980Chang et al, , 1982Chang et al, , 1985Chang et al, , 1987aChang et al, , 1987bGrody and Basist, 1996;Goodison and Walker, 1995;Tait, 1998). In particular, because of the different sensitivity of brightness temperature to snow depth and SWE at different frequencies (e.g., K-and Ka-band, Figure 5.6), algorithms based on the direct relationship between snow depth and brightness temperature spectral difference were proposed (Chang et al, 1987a):…”

Safety inspection of levees with L-band radiometry

“…From this period onwards researchers have used low frequency microwave data to derive soil moisture at different scale including in situ [2], regional [3] and global scale [4]. Other passive microwave applications over land were more related to the derivation of snow water equivalent [5], surface temperature [6] and vegetation [7]. However, so far little attention has been paid to the potential use of passive microwave remote sensing in the field of civil engineering.…”