Air-Sea Coupled Data Assimilation Experiment for Typhoons Kilo, Etau and the September 2015 Kanto-Tohoku Heavy Rainfall with the Advanced Microwave Scanning Radiometer 2 Sea Surface Temperature

[摘要]  The September 2015 Kanto-Tohoku heavy rainfall event occurred in a stationary linear convective system between Typhoons Kilo and Etau. We investigated the influence of sea surface temperature (SST) on the local heavy rainfall event using a regional air-sea strongly coupled data assimilation system based on the local ensemble transform Kalman filter (LETKF) and a nonhydrostatic atmosphere model (NHM) coupled with an ocean-surface wave model and a multilayer ocean model with an Advanced Microwave Scanning Radiometer 2 (AMSR2) level 2 (L2) SST product. From the validation of SST analyzed by the coupled data assimilation system with the Japanese geostationary multi-functional transport satellite 2 hourly SST product and in-situ observations at a moored buoy, we demonstrated that the coupled system with the AMSR2 L2 SST led to an improvement in the SST analysis. Based on the verification using radiosonde observations and radar-rain gauge rainfall analysis, the analysis of the lower-atmospheric components was improved by the air-sea coupled NHM-LETKF.

[学科分类] 大气科学

[关键词] air-sea coupled data assimilation;sea surface temperature;linear convective system;typhoon