Impact of discrepancy in atmospheric soundings between reanalysis and radiosonde data on tropicalcyclone potential intensity

Abstract

Korea Institute of Ocean Science and Technology has conducted research cruises over the western North Pacific with the research vessel ISABU since 2017. A set of 387 atmospheric soundings were obtained from the successful launch of Vaisala RS41-SG radiosondes. The atmospheric soundings were compared with the fifth generation ECMWF reanalysis (ERA5), the Japanese 55 year Reanalysis (JRA-55), and the NCEP-DOE reanalysis 2 (NCEP2). In addition, the research vessel ISABU has observed sea surface temperature (SST) with TSG. The TSG SST were compared with the reanalysis SST data: ERA5, JAR-55, and the NOAA Optimal Interpolation SST (OISST). The evaluation of reanalyses with the radiosondes reveal dry and cold biases in the low-level atmospheric soundings. The SST from ERA5 and OISST mostly corresponds to the TSG, whereas the JRA-55 underestimates SST compared to the TSG. We investigate the impact of discrepancy in atmospheric soundings between reanalysis and radiosonde data on tropical cyclone potential intensity (PI). The dry and cold biases in the low-level atmospheric soundings from reanalyses lead to the overestimated PI compared to that from the radiosondes. The impact of dry bias is relatively larger than that of cold bias on the overestimated PI.