Surface wind field analyses of tropical cyclones during TCS-08 relative impacts of aircraft and remotely-sensed observations

Abstract

The objective of this research is to investigate tropical cyclone wind field structure and development utilizing comprehensive observation sets collected during the Tropical Cyclone Structure 2008 (TCS-08) and The Observing System Research and Predictability Experiment (THORPEX) Pacific Asian Regional Campaign (T-PARC). Rare aircraft measurements in the western North Pacific are utilized to define surface wind distributions of TY Nuri, TY Sinlaku, and STY Jangmi. Stepped Frequency Microwave Radiometer (SFMR) surface winds are compared to Global Positioning System (GPS) dropwindsondes to determine eyewall slope and flight-level reduction factors. The combined SFMR and dropwindsonde wind speed observations are highly correlated (r = 0.88) with a RMSE of 2.58 m s-1. The three mature storm systems had a combined mean slant reduction factor and relative slope similar to that observed in Atlantic hurricanes. Analysis accuracy was defined by the RMSE between H*Wind analyses and 0-150 m-average dropwindsonde wind speeds. Satellite observations had the largest speed RMSE and the SFMR observations had the smallest speed RMSE. The ECMWF analyses had the largest intensity differences from the JTWC best-track intensity and SFMR-based analyses had the smallest intensity differences from the JTWC best-track intensity.