Two-dimensional, threshold-based cloud type classification using MTSAT data

Abstract

A new two-dimensional threshold diagram (2D-THR) has been developed based on maximum likelihood cloud classification results, which can readily be applied for Multi-functional Transport Satellite (MTSAT) split window datasets. Because 2D-THR was trained using northern summer 2010 data for Japan and its surrounding area, it is typically suitable only for summer. Comparison of snapshot cloud type distributions showed that 2D-THR images and the corresponding night-time microphysical colour composite images as well as 2D-THR images and Japan Meteorological Agency (JMA) cloud type images are in good agreement. A time series inter-comparison of the hourly 2D-THR cloud classification results with the JMA cloud type classification data product was performed by calculating spatial correlation of cloud percentage for 1° × 1° grid cells. For cumulonimbus, high-level, middle-level and low-level clouds over tropical and subtropical areas in the northwestern Pacific Ocean region, the spatial correlation between 2D-THR and JMA is moderate. Thus, 2D-THR cloud classification algorithm can be applied in both regions.

Acknowledgements

The authors express their gratitude to Dr. Yadu Pokhrel for his helpful comments and suggestions. This study was partially supported by the Integrated Study Project on Hydro-Meteorological Prediction and Adaptation to Climate Change in Thailand (IMPAC-T), Science and Technology Research Partnership for Sustainable Development, JST-JICA, Japan, Core Research for Evolutional Science and Technology program (CREST/JST) and Research Program on Climate Change Adaptation, Ministry of Education, Culture, Sports, Science and Technology (RECCA/MEXT). The anonymous reviewers and the editor of this journal are thanked for their valuable and very helpful comments.