Algorithm Improvements of Convective Cloud Information Product Using Himawari-8/AHI

The Japan Meteorological Agency (JMA) has begun operating of Himawari-8 since July 2015 and backup operating of Himawari-9 since March 2017. These satellites have the Advanced Himawari Imager (AHI), whose observation performance is significantly improved in terms of spectral, spatial and temporal resolution than that of the predecessor MTSAT-series satellites. Using these observation data, JMA has developed the Convective Cloud Information (CCI) product, which consists of “Cumulonimbus Area”, “Mid/Low-cloud Unknown Area” and “Rapidly Developing Cumulus Area (RDCA)”. Since July 2015, CCI product for Japan area (121E-149E, 47N-23N) had been provided every 5 minutes during the daytime in summer using Japan Area observation data of Himawari-8/AHI. In June 2016, CCI product for Japan area was updated. Since then, it has been provided every 5 minutes throughout day in all seasons. In addition, since March 2018, CCI product for Asia and Western Pacific region (85E-180E, 55N-15S) has been provided every 10 minutes using Full Disk observation data of Himawari-8/AHI. These products are utilized for safety of air navigation.

RDCA, one of the elements of CCI product, is cloud area where lightning will occur within 60 minutes. This is detected by a statistical method, i.e. the logistic regression analysis, using cloud top features, e.g. roughness and time difference of the height, as explanatory variables. It is important how to track the cloud and what to select the explanatory variable.

This presentation introduces CCI product, particularly RDCA detection algorithm, and shows the result of the survey for improvement of RDCA detection accuracy by introduction of “cloud object” tracking method and selection of appropriate explanatory variables.