Identification of rainfall area in Indonesia using infrared channels of Himawari-8 Advance Himawari Imager (AHI)

Abstract

The study aims to investigate the use of Infrared (IR) channels of Himawari-8/AHI for identification of rainfall area in Indonesia. The parameters used include the IR brightness temperature (BT) at 10.4 microns (T10.4) and seven IR BT differences (BTD), which were inferred as proxies for cloud properties. Identification of rainfall in this study is based on lookup table (LUT) approach, which is used to create probability of rainfall map. The LUTs were developed by combining the IR at 10.4 microns and IR BTD with the transportable X-band radar data, gathered during the campaign period on 15 March - 5 May 2017. Statistical skill scores were used in the study to determine the overall performance of the methods. The study indicated that the best IR and BTD combination to identify rainfall area is from the bands correlated to cloud-top height proxy (T10.4 and BTD 13.3- 10.4). In visual comparison with Global Satellite Mapping of Precipitation (GSMaP) hourly rainfall image, this IR-BTD method produced rain maps with high similarity. In general, almost all IR-BTD combinations could be used to identify rainfall area with comparable results. However combination of T10.4 and BTD at 6.2 & 7.3 micron generate high false alarm rates and underestimate the area of rainfall.