Peristiwa El Nino, keragaman hujan dan potensi Southern Oscillation Index untuk peramalan kualiti udara di Malaysia (El Nino events, rainfall and potential of Southern Oscillation Index for air quality forecasts in Malaysia)

Abstract

Abstrak

Kejadian peristiwa El Nino mempengaruhi taburan hujan di Malaysia dan memberi impak terhadap kekurangan bekalan air untuk masyarakat umum serta kegiatan pertanian. Kajian ini bertujuan untuk mengkaji pola kejadian El Nino dan hubungannya dengan hujan yang diterima serta kesan keadaan kering yang menjejaskan kualiti udara di Malaysia. Data taburan hujan selama 38 tahun dari 1970 hingga 2008 di 12 buah stesen kajicuaca utama di Malaysia dianalisis dengan menggunakan kaedah statistik korelasi, bivariat dan multivariat. Hasil kajian mendapati korelasi antara min tahunan Equatorial Southern Oscillation Index (EQSOI), Southern Oscillation Index (SOI) dan Oceanic Nino Index (ONI), iaitu indeks untuk mengukur El Nino dan jumlah taburan hujan adalah negatif tapi lemah untuk EQSOI dan ONI, tapi positif untuk SOI. Penurunan jumlah taburan hujan di barat Semenanjung Malaysia tidak terlalu ketara berbanding yang dicatatkan di stesen Malaysia Timur. Korelasi antara indeks pencemaran udara dan hujan adalah negatif kecuali di Malaysia Timur (julat antara 0.07 hingga -0.43) yang menunjukkan bahawa dalam keadaan El Nino, kualiti udara di Malaysia lazimnya rendah kerana keadaan yang lebih kering. Analisis regresi multivariat menunjukkan bahawa kualiti udara dapat diramalkan daripada parameter hujan, EQSOI dan SOI, walaupun kebaikan suai berjulat antara 7% hingga 34% sahaja. Implikasi kajian ini adalah perancangan di peringkat pihak berkuasa untuk mengatasi peristiwa jerebu tempatan yang disebabkan oleh pencemaran setempat atau pencemaran rentas sempadan terutama sewaktu keadaan kering berpanjangan yang melanda negara akibat daripada fenomena El Nino.

Kata kunci: El Nino, EQSOI, keragaman hujan, ONI, ramalan pencemaran udara, SOI

 Abstract

The occurrence of El Nino events affects the rainfall in Malaysia and has an impact on the shortage of water supply for the general public as well as agricultural activities. This study aims to investigate the patterns of El Nino incidences and its relation to the rain received and the effects of the dry conditions on the air quality in Malaysia. Rainfall data for 38 years from 1970 to 2008 in 12 major meteorological stations in Malaysia were analyzed using correlation, bivariate and multivariate statistical methods. The results showed that the correlation between the mean annual Equatorial Southern Oscillation Index (EQSOI), the Southern Oscillation Index (SOI) and the Oceanic Nino Index (ONI), the index for measuring El Nino and the amount of rainfall was negative but weak for EQSOI and ONI, but positive for SOI. The decrease in the rainfall received in the west of Peninsular Malaysia was not significant compared to that recorded in the East Malaysia. The correlation between the air pollution index and the rainfall was negative except in East Malaysia (ranging between 0.07 and -0.43), indicating that during El Nino, air quality in Malaysia was usually low due to drier conditions. Multivariate regression analysis showed that air quality can be predicted from rainfall, EQSOI and SOI parameters, although the goodness of the fit ranged from only 7% to 34%. The results of this study implied that planning at the authority level is necessary to overcome the local haze events caused by local pollution or transboundary pollution, especially during prolonged dry conditions that hit the country due to the El Nino phenomenon.

Keywords: El Nino, EQSOI, rainfall, ONI, air quality prediction, SOI

https://doi.org/10.17576/geo-2018-1402-02