Sains Malaysiana 48(11)(2019): 2325–2334

http://dx.doi.org/10.17576/jsm-2019-4811-04

 

Prediction Skill of NCEP CFSv2 for Seasonal Precipitation and Surface Air Temperature Forecast over Southeast Asia

(Kemahiran Peramalan NCEP CFSv2 untuk Kerpasan dan Suhu Udara Permukaan Musiman di Asia Tenggara)

 

SITI AMALIA, FREDOLIN TANGANG, SHEAU TIEH NGAI & LIEW JUNENG*

 

Centre for Earth Sciences and Environment, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor Darul Ehsan, Malaysia

 

Diserahkan: 1 April 2019/Diterima: 15 Ogos 2019

 

ABSTRACT

Climate Forecast System version 2 (CFSv2) is the ocean-atmosphere-land coupled model and the latest version of seasonal climate forecast from National Centers for Environmental Prediction (NCEP). This study presents the prediction skill of seasonal precipitation and surface air temperature forecasting from CFSv2 over Southeast Asia. The objective of the study was to verify the prediction accuracy of CFSv2 by quantifying the deterministic quantities in term of correlation coefficients with respect to different lead times and target seasons based on a the 28-year ensemble means (1983/84 - 2010/11) for each variables. Additionally, the prediction skill of 20 sub-regions over Southeast Asia are verified with observation for regional assessment of the accuracy of seasonal precipitation and surface air temperature forecasted by CFSv2. In general, the result showed that the prediction skill of CFSv2 for seasonal precipitation and surface air temperature forecasting is reasonable, especially prediction skill after lead month-0 for all target seasons compared to other lead months. The lowest prediction skill is after lead month-6. Overall, the prediction skill of seasonal surface air temperature forecasting is better than precipitation. Moreover, the result obtained in this study highlights the advantages of using an ensemble technique for seasonal forecasting in Southeast Asia.

 

Keywords: Ensemble techniques; forecast skill assessment; NCEP CFS; seasonal forecasting; Southeast Asia

 

ABSTRAK

Sistem Ramalan Iklim versi kedua (CFSv2) merupakan sebuah model laut-atmosfera-darat berpasangan dan versi terkini model peramalan iklim bermusim dari Pusat Kebangsaan untuk Ramalan Sekitaran (NCEP). Kajian ini mengemukakan kemahiran ramalan kerpasan dan suhu udara permukaan bermusim dari CFSv2 di Asia Tenggara. Objektif kajian ini adalah untuk mengesahkan ketepatan ramalan CFSv2 dengan mengukur kuantiti deterministik dalam istilah pekali korelasi berdasarkan analisis terhadap min kelompok 28 tahun (1983/84-2010/11) bagi setiap pemboleh ubah pada masa bulan kedepan dan sasaran musim yang berbeza. Tambahan pula, kemahiran ramalan 20 subkawasan di Asia Tenggara dikesahkan dengan pemerhatian untuk melihat secara terperinci ramalan kerpasan dan suhu udara permukaan bermusim yang telah diramalkan oleh CFSv2. Secara umumnya, keputusan menunjukkan bahawa kemahiran ramalan CFSv2 bagi ramalan kerpasan dan suhu udara permukaan bermusim adalah munasabah terutama sekali kemahiran ramalan selepas 0-bulan kedepan untuk kesemua sasaran musim berbanding dengan bulan kedepan yang lain. Kemahiran ramalan paling rendah adalah selepas 6-bulan kedepan. Secara keseluruhannya, kemahiran ramalan bagi peramalan suhu udara permukaan adalah lebih baik daripada kerpasan. Tambahan pula, kajian ini telah menekankan kelebihan menggunakan teknik kelompok bagi peramalan bermusim di Asia Tenggara.

 

Kata kunci: Asia Tenggara; NCEP CFS; penilaian kemahiran ramalan; peramalan bermusim; teknik berkelompok

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*Pengarang untuk surat-menyurat; email: juneng@ukm.edu.my

 

 

 

 

 

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