Deteksi Overshooting Top Menggunakan Satelit Himawari-8 dan Dampaknya terhadap Cuaca Permukaan di Wilayah Jabodetabek ( September – November 2017)

Abstract

Overshooting top (OT) results from a strong updraft on a cumulonimbus cloud that can penetrate to tropopause layer. The IRW-texture method can detect OT using the Himawari-8 satellite image of the IR-1 and visible channels. The IR-1 channel image determines the cloud top temperature must be less than 215 K, and the cloud top temperature is colder than 2.5 K from the NWP tropopause temperature, then computes the mean anvil temperature surrounding OT and subtract with the coldest cloud top temperature, so the difference is more than 6.5 K, then OT is identified. The visible channel image looks at the cloud texture shaped like a bump. OT occurrence is always associated with lightning activity, where OT, which results from convective clouds penetrating the tropopause layer, can increase lightning activity. Thus, an increase in lightning activity may indicate that OT occurs in a region. Research conducted from September to November 2017 in the Jabodetabek area obtained 14 cases of OT occurrence. OT mainly occurred between 14.00 to 16.00 WIB and mostly happened in the Bogor region. OT can cause bad weather on the surface, such as heavy rain, hail, and strong winds in a radius of up to 40 km.