梅雨前線上に発生したメソ低気圧のアンサンブル予報実験

Abstract

Ensemble forecast experiments were conducted to investigate the mechanisms and predictability of a meso-scale cyclone observed by vessels in the East China Sea during the field campaign for the Baiu frontal zone and Kuroshio in late June to early July 2022. The forecast from 1200 UTC, 18 June predicts a meso-scale cyclone with heavy precipitation similar to the one observed by the three vessels on 19th. Some ensemble members reproduce the precipitation more realistically. Stronger cooling in the boundary layer of the improved forecast reduces the underestimation of sea-surface flux. However, the convective available potential energy is not intensified due to the significantly lower sea-surface temperature prescribed in the model than the reports from the vessels. The sea-surface flux estimated from ship reports varies with the potential temperature difference and wind speed associated with the meso-scale disturbances to compensate the boundary-layer potential temperature consumed by convection.