Hubungkaitan intensiti hujan dengan suhu kecerahan awan menerusi aplikasi maklumat satelit geo-pegun MTSAT-IR (Relationship between rainfall intensity and cloud brightness temperature measured through MTSAT-IR geo-stationary satellite application)

Abstract

Maklumat tentang intensiti hujan dari stesen cerapan hujan sangat berguna bagi tujuan peramalan. Penggunaan kaedah gema radar bagi menganggar curahan hujan mempunyai kelemahan tersendiri terutamanya terhadap batasan wilayah jangkauannya yang terhad serta aspek teknikal khususnya aspek kalibrasi peralatan yang memerlukan kepakaran dan kos yang tinggi. Artikel ini menganalisis hubungan antara suhu kecerahan awan berdasarkan maklumat inframerah satelit geo-pegun MTSAT dengan intensiti hujan di permukaan bumi. Pemilihan satelit geopegun MTSAT dilakukan memandangkan kekerapan imej secara temporal yang sangat mencukupi (24 imej/hari) serta resolusi spatialnya yang sederhana (4 km/piksel). Kajian awalan ini telah menunjukkan bahawa maklumat suhu kecerahan awan daripada kedua-dua jalur inframerah dan wap air MTSAT-IR berupaya dalam menganggarkan intensiti hujan dalam tempoh kajian yang dilakukan. Bagaimanapun, terdapat banyak usaha yang perlu dilakukan sebelum pembentukan model anggaran hujan berdasarkan maklumat imej satelit MTSAT-IR yang mempunyai tahap kesahihan dan kebolehpercayaan yang tinggi.

Katakunci: hujan, intensiti hujan, kumulonimbus, MTSAT-IR, satelit geo-pegun, suhu kecerahan awan

Station-based rainfall data are usually used in forecasting and estimating areal rainfall patterns. The use of radar in estimating and predicting areal rainfall, however, has its own weakness in terms of being limited within restricted regions as well as requiring high expertise in calibration works and involving enormous costs. This article analysed the relationship between cloud brightness temperature based on geostationary MTSAT-IR satellite and rainfall intensity in urban areas. The application of the MTSAT-IR satellite in this study is based on its high temporal frequency of images (24 images/day) and moderate spatial resolutions (4km/pixel). This preliminary investigation proved that the cloud temperature information both from infrared and water vapour bands has the capability of estimating rainfall intensity during the study period. However, substantial works have to be done before a valid rainfall estimation model based on the MTSAT-IR satellite images can be developed.

Keywords: cloud brightness temperature, cumulonimbus, geo-stationary satellite, MTSAT-IR, rainfall, rainfall
intensity