WindSat Polarimetric View of Greenland 1
Abstract — WindSat has systemically collected the first global passive polarimetric data over both land and ocean at three frequencies: 10.7, 18.7 and 37 GHz, including the brightness temperatures at vertical and horizontal polarizations, and the real and imaginary parts of the cross-correlation of...
| Main Authors: | , , |
|---|---|
| Other Authors: | |
| Format: | Text |
| Language: | English |
| Subjects: | |
| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.391.8451 http://www.mers.byu.edu/long/papers/conf/IGARSS2006_Li.pdf |
| Summary: | Abstract — WindSat has systemically collected the first global passive polarimetric data over both land and ocean at three frequencies: 10.7, 18.7 and 37 GHz, including the brightness temperatures at vertical and horizontal polarizations, and the real and imaginary parts of the cross-correlation of the vertical and horizontal polarizations. Prior to the launch of WindSat, it was commonly believed that land polarimetric signatures at satellite footprint scales are below instrumental noise levels and do not have any useful geophysical information. On the contrary, WindSat polarimetric data exhibit distinct geophysical and observation geometry signatures, particularly over Greenland and Antarctic where the signatures are related to snow accumulation, melting and metamorphism. The third and fourth Stokes parameters show well defined, large azimuth modulation which is correlated with geophysical variations, particularly with snow metamorphism, and has consistent seasonal variation. We use simple empirical models to separate and quantify such azimuthal modulations and geophysical changes. By comparing the temporal variations of harmonic coefficients and brightness temperature signatures in vertical and horizontal polarization channels, we find that both volume and surface scattering have important contributions to the polarimetric signature. Such signatures are relatively weak in the summer, when sastrugi are small and surface scattering is significant, and are strongest in spring, when the sastrugi are larger and volume scattering is important. Keywords-polarimetric microwavr radiometry; WindSat; snow; Greenland |
|---|