Estimating the intensity of tropical cyclone in Western North Pacific basin with AMSU-A brightness temperature

Advanced Microwave Sounding Unit (AMSU)is well suited to analysis the warm core structure of tropical cyclone (TC) because certain wavelengths of microwave energy are able to penetrate the cirrus above TC. Through the radiative and hydrostatic equation, the upper tropospheric brightness temperature anomalies of TC are related to surface pressure anomalies. With the track of each TC happened in Western North Pacific basin during the 2002 similar to 2006 seasons, 47 TCs and 183 cases were collected according to the overpass of AMSU-A flown aboard NOAA-16/17/18. They were used to develop a linear statistical relationship between the warm core anomalies and the TC intensity report from operational centers. Further improvements in correlation, and intensity estimate accuracy, were possible through application of combining the information from AMSU-A channel 7 and 8 together and a proposed algorithm, which was devised to try to correct the bias from receiving warm core microwave radiation due to the unevenly distribution of AMSU-A footprints, and the correlation coefficient and standard deviation were found to be 0. 80 and 12.2 hPa, respectively. Independent application of the corrected algorithm in two typhoons (0414 Rananim and 0608 Saomai), which influenced China heavily in recent years, showed the mean absolute errors were about 6 hPa.