Intraseasonal and interannual analysis of the organization of mesoscale convective systems in the Indo-Pacific region using satellite measurements

The organization, strength, and distribution of mesoscale convective systems (MCSs) are related to the evolution of the El Nino Southern Oscillation (ENSO) from pre-onset to decay. The present study investigates the influence of sea surface temperature, zonal winds, variation of diurnal cycle, and Madden-Julian Oscillation (MJO) on the organization, strength, and distribution of MCSs over the Indo-Pacific region for understanding ENSO. This study is based on the Tropical Rainfall Measuring Mission's (TRMM) precipitation features datasets during boreal winters of 2001--02 to 2006--07.;The Hot Spot analysis of MCSs suggests that the systems are predominantly found clustered in the Maritime Continent (MC) and West Pacific Regions (WPRs), and are preferentially observed over ocean compared to land. Time series analyses found that 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 sea surface temperature (SST) for this month peaked between 29-30° Celsius. Convective intensity proxies demonstrated a strong positive relationship with SST, but no relationship was noted between SST and median volumetric rainfall. The zonal wind exploration indicates that strong westerly wind occurred in the Indian Ocean prior to the 2002--03 El Nino for January. The wind direction demonstrated that the maximum number of storms occurred in January 2002 when the prevailing wind direction was from the north and northwest. A cluster of higher zonal wind speeds and MCSs were noted in the Indian Ocean, consistent with storms being related to westerly wind burst events.;The magnitude of the diurnal cycle suggests that the number of MCSs peaks in the late evening over ocean and in late morning over land. The diurnal cycle over ocean is such that the number of MCSs increases from 7 AM to 10 PM but volumetric rainfall does not follow the pattern and is fairly constant throughout that day.;The relationship between MJO and MCSs is significant. The plotting of MCS observations revealed that 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 to the WPR. The strong active phase of the MJO was found in the Indian Ocean during January 2002. The MJO analysis indicates that MCSs have an impact on westerly wind bursts (WWBs) during the eastward propagation of the MJO and the WWBs have been linked to the initiation of El Nino in the Pacific. The role of extreme precipitation on food security, coastal flooding and erosion, and coastal ecosystems are discussed in the light of coastal management and policy implications.