Moisture transport and atmospheric conditions supporting the formation of self-organization convective cloud during heavy rainfall over West Java (15-16 July 2022) Anis Purwaningsih
National Research and Innovation Agency
Abstract
Devastating floods occurred over West Java for 15 -16 July 2022. The main triggers of those floods were heavy rainfall that reached 155 mm/day at the West Java Climatology station. The indication of self-organization convective cloud developments is identified by the previous study. However, the elaboration on moisture sources and factors related to cloud formation has not been well described. This paper aims to track the moisture source of this heavy precipitation and understand the meteorological and oceanic factors supporting cloud formation resulting in heavy rainfall. We used a lagrangian approach (HYSPLIT model) to track moisture responsible for heavy precipitation over three different regions (Garut, Tangerang, and Bogor) by utilizing GDAS and ERA5 data for model input, during rainfall peaks. For three different locations tracking was conducted over three different tracking altitudes (500 m, 1000 m, and 3000 m), to determine the vertical structure of moisture and other meteorological factors (CAPE, CINH, and convergence). For analyzing the time series of rainfall, the GSMaP data was employed. Results indicate that there were two rainfall peaks at 07 UTC, on 15 July 2022, and 00 UTC, on 16 July 2022. Output models indicate that 72 hours prior to the first rainfall peak, moisture was mainly from the Southeastern Tropical Indian Ocean (SETIO) over an altitude of 1000 to 2500 m. While in the second rainfall peak, moisture advected from SETIO over a lower altitude (0 to 1500 m). Moreover, moisture recycling over Java Island was also detected to contribute as the source of this second peak. A high Integrated Vertical Moisture Transport (over 300 kg.m-1.s-1) supported the moisture advection in the second and first peaks, as the high moisture content transported from the source region toward the flooding locations. Overall, this study indicates that oceanic moisture over SETIO and terrestrial moisture over Java contributed to heavy rainfall.
