Evolution of Mesoscale Convective Systems and its Relationship with the Madden-Julian Oscillation in the Indo-Pacific Region

Abstract

In this study we investigated the influence of sea surface temperature (SST) and Madden-Julian Oscillation (MJO) on the organization, strength, and distribution of Mesoscale Convective Systems (MCSs) over the Indo-Pacific region for understanding El Nino Southern Oscillation (ENSO). The study is based on the Tropical Rainfall Measuring Mission's (TRMM) precipitation features dataset during boreal winters of 2001-02 to 2006-07. The results of time series of hot spot analyses show that MCSs are predominantly clustered in the Maritime Continent and West Pacific Regions, and are preferentially observed over ocean compared to land. The largest quantity of MCSs were observed to the south of the equator in January 2002, and the distribution of MCSs as a function of SST for these months peaked between 29-30 o Celsius. MJO explains 11% to nearly 30% of the characteristics of MCSs in the Indo-Pacific. The percentage of MCSs over the ocean in January is larger when the MJO is in the active phase than the passive phase from the Indian Ocean to the West Pacific Region. The warm waters under the MCSs may be related to the coupled MJO process that convectively generate and maintain the storms. The effect of the MJO is strongest when it is located within the Maritime Continent region. The MJO analysis indicates that MCSs are more likely accompanied by westerly winds during the eastward propagation of the MJO and the westerly wind bursts have been linked to the onset of El Nino in the Pacific.