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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 Received: 1 April 2019/Accepted: 15
August 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
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