Analysis of convective cloud presence surrounding whirlwind events in Yogyakarta, Indonesia

Whirlwinds are a meteorological disaster that often strikes Indonesia's territory, including the Special Region of Yogyakarta on Java Island. The formation of this small-diameter vortex of rapidly spiraling air depends on the presence of convective clouds, particularly Cumulonimbus (Cb). This research was intended to analyze the spatiotemporal distribution of convective clouds in the region according to whirlwinds recorded in 2019. The research used historical data consisting of the dates and locations of whirlwinds throughout 2019 to determine their spatial distribution. For this purpose, Himawari-8 images with bands 13 (IR1) and 15 (IR2) captured on said dates were processed using the split windows technique in SATAID software. Other data like daily synoptic weather, landscape, topography, and land use were also analyzed to provide atmospheric and land conditions surrounding the weather events. The analysis results showed convective clouds, especially Cumulonimbus (Cb), were present on every date of the event with various distribution and massiveness and always appeared preceding the whirlwinds. On March 17, 2019, the most massive convective cloud coincided with three whirlwinds striking Sleman, Bantul, and Kulon Progo. Tropical cyclone Savannah that hit the southern part of Java Island, including the study area, created atmospheric anomalies responsible for this cloud formation. Low air pressure, high humidity, rainfall, level topography, and land used for settlements and rice fields are concluded as contributing to the convective cloud and whirlwind formation in the region. © 2021 SPIE.