Level and source of predictability of seasonal rainfall anomalies in Malaysia using canonical correlation analysis

Abstract

This study examines the level and origin of seasonal forecast skills of rainfall anomalies in Malaysia. The forecast models are based on an empirical technique known as the canonical correlation analysis (CCA). The CCA technique searches for maximally correlated coupled patterns between sets of predictor and predictand matrices. The predictive skills of five predictor fields, namely station rainfall in preceding seasons (i.e. the predictand itself), local sea surface temperature (SST) over the western Pacific sector, quasi-global SST, sea level pressure, and northern hemisphere 700 hPa geopotential height, are investigated. The sequence of four consecutive 3-month predictor periods is used to capture evolutionary features in the predictor fields. The predictor-predictand setup is designed such that the predictor fields are followed by a lead-time ranging from 0 to 9 months and then by a single predictand period of 3 months' duration. The skills are estimated in hindcast mode using the one-year-out version of the cross-validation technique. Skill estimates are expressed as temporal correlation coefficients between forecasts and observed values.A series of experiments with different predictor combinations reveal that the model with quasi-global SST alone produces most favourable forecast skills. The forecast skills of this model generally outperform the persistence forecast. Moreover, the model also has higher forecast skills in the East Malaysian region compared to those in Peninsular Malaysia. The forecast skill peaks during the late Northern Hemisphere winter season (January-February-March (JFM)) with a secondary maximum during the early summer season (May-June-July, (MJJ)). The average forecast skills are between 0.3-0.5 for up to 5 months' lead-time in the East Malaysian region and this can be considered very useful for the appropriate users. In the Peninsular Malaysia region, the forecast skills are generally weak, although some stations registered modest skills even at a 5-month lead-time. For both prediction periods, the source of predictability originates from anomalous SST conditions associated with the El Niño-Southern Oscillation (ENSO) phenomenon. Generally, during a La Niña (an El Niño) event, regions in northern Borneo experience excess (deficit) rainfall during the JFM period. Similar conditions are experienced during the MJJ period except that the impact tends to be more widespread throughout the country. Interestingly, the origin of predictability during the JFM period can be traced to typical ENSO events, while ENSO events of longer duration are responsible for the MJJ period.

Determination of forest water yield in Malaysian tropical watershed using calibrated satellite-based rainfall data

“…On overall perspectives, the forest water yield which evaluated on spatial basis using satellite measurement agrees with most previous rainfall and climatology studies such as Desa et al [21], Juneng et al [22] and Juneng et al [23].…”

Rainfall Characteristics and Regionalization in Peninsular Malaysia Based on a High Resolution Gridded Data Set

“…Hence, together with the lower pressure, the increases the rainfall anomalously over the region as shown by the positive lagged correlations in Table 6. Conventionally, the warm ENSO phases are associated with dry rainfall anomalies over Malaysia [17] during the development of ENSO events and this relationship was used to forecast the seasonal rainfall anomalies in the country [20]. The lagged positive relationship found in this study is an important consideration in predicting seasonal rainfall anomalies over Peninsular Malaysia with a longer lead time.…”

“…The relation between Malaysian rainfall anomalies, sea surface temperature and El Niño-Southern Oscillation (ENSO) were studied by Tangang and Juneng [17] and Juneng and Tangang [19,20]. The global warming/temperature trends and variations were investigated by Tangang et al [21] and Ng et al [22].…”

Study on Precipitation and Its Relation to Pressure and Temperature Over Malaysia During The ENSO Phenomenon

“…Fenomena El Niño juga memberi impak penting ke atas rantau Asia Tenggara, terutamanya dari aspek anomali iklim serantau dan kesejahteraan sosioekonomi penduduknya (Juneng et al 2008;Feng et al 2010). Malaysia terjejas secara langsung akibat kemarau El Niño dimana berlaku kekurangan air dan jerebu yang berterusan (Tangang et al 2004;Juneng et al 2005).…”