P5.30
Using polarimetric two-stream radiative transfer model to study microwave polarimetric signatures
Quanhua Liu, CIRA/Colorado State Univ., Ft. Collins, CO; and F. Weng
There are growing needs to study polarimetric signatures at microwave frequencies for developing a physical retrieval algorithm of sea surface wind vector. In particular, the upcoming satellite sensors such as WindSAT/Coriolis and Conical Microwave Imager Sounder (CMIS) of U.S. National polar-orbiting Environmental Satellite System (NPOESS) will have full Stokes vector at low frequencies in addition to the polarization measurements at higher frequencies. The full polarimetric signatures allow us to derive both sea surface wind speed and direction which are very important for weather forecast and climate monitoring. The polarimetric two-stream radiative transfer model used here is extremely fast so that the model can be used in data assimulation and for physical retrievals of operational products. It is shown that the brightness temperature within the range of satellite viewing angle calculated from the polarimetric two-stream model differs from that obtained from the sixteen-stream model by no more than 1 K for various atmospheric and surface conditions including precipitation. Simulations show all four components of Stokes vector are sensitive to the sea surface wind direction. The variation of the first and second components (intensity and polarization) to the sea surface wind direction is about 2 K. The variation of the third component of Stokes vector can reach up to 4 K. The dependence of the sensitivity on wind direction and speed as well as frequency is discussed. The polarimetric signatures are also beneficial to other products such as sea surface wind speed and total precipitable water. The improvement to those products is discussed.
Poster Session 5, New Technology and Methods
Wednesday, 17 October 2001, 2:15 PM-4:00 PM
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