Multi-source Satellite Remote Sensing Of Tropical Cyclone Intensity And Structure And Its Applications

In this paper,wind fields of 257 tropical cyclones monitored by L-band Soil Moisture Active Passive(SMAP)radiometer and 118 tropical cyclones monitored by C-band Synthetic Aperture Radar(SAR)onboard Sentinel-1A/B(S1-A/B)and RADARSAT-2(RS-2)are used to develop technical methods for estimating typhoon intensity and structure parameters(the radius of 34,50 and 64 kt winds,hereinafter referred to as R34,R50,R64).The estimated results are compared with the best-track data to verify the accuracy of the estimated parameters.The Root Mean Square Errors(RMSEs)of R34,R50 and R64 are 57.8?40.4 and 31.6 km for SMAP radiometer,and 40.1?30.5 and 30.2 km for SAR,respectively.The bias and RMSE of intensity parameter are-0.2 m/s and 5.8 m/s for radiometer,and 4.4 m/s and 9.1 m/s for SAR,respectively.The differences between satellite calculations and best-track data may be related to the spatial average effect of satellite sensors,the swath width,the inherent uncertainty of the best-track data itself and different definitions of intensity between satellite estimates and best-track data.Taking typhoon Lionrock as an example,we find that the structure and intensity parameters of typhoon can be extracted from a combination of SMAP radiometer and SAR winds,which are more accurate than those from single satellite winds.The multi-temporal wind observations from SMAP radiometer and SAR clearly show the evolution of typhoon Noru.The derived maximum wind speed shows similar variation with the best-track data,and shows a good relationship with sea surface temperature(SST)underlying typhoon Noru.It can be illustrated that the cooperative use of multi-source satellite observations from the active and passive microwave remote sensing can better extract typhoon parameters and monitor dynamic evolution,and is of great value to the scientific research and operational applications of typhoons.Based on 104 SAR wind observations,considering more influence factors(intensity,translation,environmental wind shear and latitude),the technical method for the development of the parametric asymmetry wind model is established,and the model is finally constructed.The model can reproduce the azimuthal asymmetry characteristics.Compared with the symmetrical model and the asymmetric model which simply considers translation effects,the radial wind profile distributions simulated by the derived model are closer to the remote sensing observations from SAR and the Stepped Frequency Microwave Radiometer(SFMR).The model can be used in the absence and presence of wind field observations.It is suitable for case analysis when prior observation is not available.With available observations,the simulated wind distributions should be better than those from traditional symmetrical model and the asymmetric model which simply considers translation effects.The model has the potential to be further improved and developed,and can better adapt to the requirements of scientific research and operational use related to typhoons.