An Objective TC Intensity Estimation Method Based on Satellite Data

Researches prove that TC (tropical cyclone) intensity is mainly determined by the top cloud convection strength, distribution and size. Then how to extract this information from TC cloud image is very important for TC intensity estimation. In 1988, Adler put forward a method named CST (convective-stratiform technique) to extract tropical convective cores from TC cloud image. Using MTSAT (multi-functional transport satellite) IR1 black body temperature data, the TC cloud top strong convection is extracted. Based on the convective cores number, convective core distance to TC center and convective core black body temperature extreme value, which are closely related to TC intensity, a TC intensity (expressed by V_max, the maximum sustained wind speed near surface TC center) estimation model is put forward using stepwise regress method. The experiment result shows that there is a linear correlation between their estimation error and their intensity for V_max >40 m·s^-1 and V_max < 18 m·s^-1 samples. So according to the estimation error distribution a linear revision is carried out.Statistical tests show this model is equivalent to Dvorak method and AMSU in TC intensity estimation accuracy. It's also reliable based on the relationship between the convective cores, convective cores distribution, brightness temperature and TC intensity. It could be used in all TC life span automatically and objectively, so it could be applied in the operation.Comparing with the advanced objective dvorak technique (AODT) and objective Dvorak technique (ODT), this algorithm gives accurate results in the Western North Pacific, but it's simpler with no complicated pattern types identifying process or other rules. A fixed radius of 135 km area is used as TC convective cores searching effective area in the model, but actually the maximum wind speed radius of the TC is variable, the TC size and the strongest convective area size are different for different TC in different stage. So using the fixed searching area may affect TC intensity estimation accuracy. The research on how to get the dynamical maximum wind speed radius would be carried out in the future.