A retrieval method of tropical cyclone wind speed and sea level pressure based on HY-2 satellite data
Tropical cyclones are accompanied by different degrees of rainfall,which attenuates the remote sensing parameters obtained by the active microwave remote sensor to varying degrees,resulting in the underestimate of wind speed,and the wind speed above 30 m/s cannot be observed effectively.Based on the comprehensive consideration of the sensitivity of HY-2 satellite radar altimeter and calibration microwave radiometer to wind speed observation,this paper proposes a new method for the joint observation of tropical cyclone wind speed and sea level pressure based on HY-2 satellite active and passive microwave remote sensor,that is,the influence of rainfall on radar altimeter observation during typhoon is compensated by using the brightness temperature of calibration radiometer T18 channel,to improve the observation ability of high wind speed;Based on the effective observation of typhoon high wind speed and the relationship between typhoon central pressure difference and wind speed difference,an inversion method of sea surface pressure is proposed.The method can realize high-precision observation of wind speed above 50 m/s.The absolute error between the method and SFMR airborne observation data is within 2 m/s,and the RMSE is 1.0 m/s.The absolute errors of the proposed sea level pressure observation method compared with SFMR airborne observation data and CMA,JTWC and NHC are all within 10 hPa,and RMSE is 4.6 hPa,which proves the reliability of the method.At the same time,the method in this paper also has the ability to observe the sea level pressure under the condition of medium and low wind speed.Based on HY-2 satellite data,a method for active and passive microwave remote sensing to jointly observe tropical cyclone sea surface wind speed and pressure is presented.This method is suitable for satellite radar altimeter and correction microwave radiometer data,which can make up for the shortage of active microwave remote sensing payload observation ability under the condition of tropical cyclone rainfall,and has the ability to simultaneously obtain the information of tropical cyclone wind speed and sea level pressure.The deficiency lies in that,due to the time and space limitations of HY-2 satellite observation data in the study,there are few comparison data that meet the requirements of verification.Subsequently,HY-2 satellite observation data for a longer period of time and global tropical cyclone data will be accumulated for more comprehensive data analysis and evaluation.In terms of data evaluation,it is proposed to apply the method in this paper to the Jason series of satellite observation to obtain the satellite observation data of tropical cyclone in a long time series,and realize more observation of typhoon or hurricane wind speed,so as to give more objective statistical analysis results.At the same time,it can also further test the applicability of the method in this paper on similar satellites.In terms of sea level pressure observation,the method in this paper is proposed to be further improved and evaluated with NDBC buoy data in order to realize sea level pressure observation under non-cyclone conditions and expand radar altimeter.
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