IDENTIFIKASI HAIL BERDASARKAN ANALISIS FAKTOR CUACA DAN PEMANFAATAN TEKNIK RGB SERTA SWA PADA CITRA SATELIT HIMAWARI 8 (STUDI KASUS: KEJADIAN HUJAN ES DI KABUPATEN MALANG PADA 2 MARET 2021) - Marinda Nur Auliya; Aditya Mulya (BPPT, 2022)
Intisari Fenomena hujan es di Malang terjadi di Kecamatan Sumbermanjing Wetan (8,1 LS dan 112,4 BT) pada 2 Maret 2021. Penelitian dilakukan dengan menganalisis faktor cuaca global, regional, lokal, dan menganalisis karakteristik awan dari data citra satelit menggunakan metode RGB dan SWA saat terjadi hujan es. Hasil penelitian menunjukkan bahwa ENSO, anomali suhu permukaan laut, dan MJO tidak berpengaruh terhadap kejadian hujan es. Peta streamline menunjukkan adanya geser angin dan siklon tropis di sekitar Malang. Berdasarkan analisis cuaca permukaan menunjukkan adanya penurunan suhu, yaitu sebesar 4.4°C pada pukul 07.00 UTC hingga 08.00 UTC dan 3.6°C pada pukul 08.00 UTC hingga 09.00 UTC serta kenaikan kelembapan yang signifikan, sebesar 10% pada pukul 07.00 UTC hingga 09.00 UTC. Berdasarkan suhu puncak awan, dapat dianalisis bahwa tahap pertumbuhan terjadi pada pukul 06.00 UTC hingga 07.00 UTC. Tahap matang terjadi dari 07.00 UTC hingga 09.00 UTC. Tahap disipasi terjadi dari pukul 09.00 UTC hingga 10.00 UTC. Suhu puncak awan terendah terjadi pada pukul 07.40 UTC dan 8.40 UTC, yaitu -68,2°C. Berdasarkan metode RGB dan SWA menunjukkan bahwa pada pukul 06.40 UTC tidak banyak awan konvektif di lokasi kejadian, pada pukul 07.40 UTC dan 08.40 UTC terdapat banyak awan konvektif, yaitu cumulonimbus di lokasi kejadian, serta pada pukul 09.40 tutupan awan sudah banyak berkurang di lokasi kejadian. Kedua metode tersebut dapat menggambarkan adanya awan konvektif pada saat kejadian hujan es, namun metode SWA dapat lebih spesifik menunjukkan adanya awan konvektif jenis cumulonimbus. Abstract The hail phenomenon in Malang occurred in Sumbermanjing Wetan District (8.1° South Latitude and 112.4° East Longitude) on March 2, 2021. The study was conducted by analyzing global, regional, local weather factors, and analyzing cloud characteristics from satellite image data using the method RGB and SWA during hail. The results showed that ENSO, sea surface temperature anomalies, and MJO had no effect on the incidence of hail. The streamline map shows wind shear and tropical cyclones around Malang. Based on the analysis of the surface weather, it shows a decrease in temperature, which is 4.4°C at 07.00 UTC to 08.00 UTC and 3.6°C at 08.00 UTC to 09.00 UTC as well as a significant increase in humidity, by 10% at 07.00 UTC to 09.00 UTC. Based on the cloud top temperature, it can be analyzed that the growth stage occurs from 06.00 UTC to 07.00 UTC. The ripe stage occurs from 07.00 UTC to 09.00 UTC. The dissipation stage occurs from 09.00 UTC to 10.00 UTC. The lowest cloud top temperatures occurred at 07.40 UTC and 8.40 UTC, which was -68.2°C. Based on the RGB and SWA methods, it shows that at 06.40 UTC there were not many convective clouds at the incident location, at 07.40 UTC and 08.40 UTC there were many convective clouds, namely cumulonimbus at the scene, and at 09.40 the cloud cover had decreased a lot at the incident location. Both methods can describe the presence of convective clouds during hail events, but the SWA method can be more specific in showing the presence of cumulonimbus convective clouds.