Abstract
The 89 and 150 GHz channels operated in window are sensitive to precipitation and humidity. The 183 GHz humidity-sensitive channels and 118 GHz temperature-sensitive channels of the Microwave Humidity and Temperature Sounder (MWHTS) on the Chinese Feng Yun 3C MWHTS (FY-3C MWHTS) polar-orbit meteorological satellite responds in part to precipitation. Combining 118 and 183 GHz channels, the paper develops a passive sub-millimeter atmospheric profile and precipitation retrievals algorithm for MWHTS onboard the FY-3C (Feng Yun-3C) satellite. The retrieval algorithm employs a number of back propagation neural network estimators trained and evaluated using the validated global reference physical model NCEP/WRF/ARTS and works for land and seawater with latitude between -40 to 40 degree. NCEP data per 6 hours were downloaded to run the Weather Research and Forecast model WRF, and to derive the typical precipitation data for the whole world. The Atmospheric Radiative Transfer Simulator ARTS is feasible for performing simulations of atmospheric radiative transfer. The results show that the profile retrievals using BP-NN algorithm has the best correlation with those from radiosonde, which is less than 18% and 1 K of root mean square error, respectively. For precipitation rate retrievals, a much better agreement is reached with rain gauge and ECMWF datasets, the RMS is between 0.80 to 30.24 mm/h for sea surface and 0.789 to 33.11 mm/h for land surface according to the classification by precipitation type. Also, the analysis of retrievals located in Tibetan plateau is provided as an example to justify the robustness and performance of retrieving model.
Highlights
There are a number of researchers working on retrieving of temperature and humidity profiles and a lot of results have been obtained, which include AMSU-B onboard NOAA-K, L, M satellite with observing frequencies at 89 GHz, 150 GHz, (183.3 ± 1) GHz, (183.3 ± 3) GHz and (183.3 ± 7) GHz
When the inversion layer was thick enough, the neural network inverse model can be well reflected for the details of atmospheric temperature changes
The retrievals showed that the root mean square (RMS) of atmospheric temperature profile was less than 2.5 K, RMS of atmospheric relative humidity profile was17.7%, which can be converted to atmospheric absolute humidity, and the RMS was less than 0.35g/m3 as shown in Figure 4 to Figure 5
Summary
There are a number of researchers working on retrieving of temperature and humidity profiles and a lot of results have been obtained, which include AMSU-B onboard NOAA-K, L, M satellite with observing frequencies at 89 GHz, 150 GHz, (183.3 ± 1) GHz, (183.3 ± 3) GHz and (183.3 ± 7) GHz. Passive microwave techniques have long been used to retrieve precipitation over sea using frequencies lower than 100 GHz. The longer wavelengths are typically absorbed by precipitation over sea, making it appear warm against the reflective sea, but it is not for precipitation over land, since precipitation generally scatters the shorter wavelengths producing reduced brightness temperatures. The longer wavelengths are typically absorbed by precipitation over sea, making it appear warm against the reflective sea, but it is not for precipitation over land, since precipitation generally scatters the shorter wavelengths producing reduced brightness temperatures In both cases the highly variable brightness temperatures of the precipitation-free background, over land, limit the accuracy of these precipitation estimates [6]
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