The Properties of Mesoscale Convective Systems in Indonesia Detected Using the Grab 'Em Tag 'Em Graph 'Em (GTG) Algorithm

Abstract

 A mesoscale convective system (MCS) is organized thunderstorms with connected anvils, which has significant impact to the global climate. Focusing on MCS over the Maritime Continent of Indonesia, this study aims to gain a better understanding on the properties of MCSs over the study area. The “Grab 'em Tag 'em Graph 'em” (GTG) tracking algorithm is applied to hourly Multi-functional Transport Satellite-1R (MTSAT-1R) data for two years period to observe the distribution of MCSs and the evolution of MCSs along their lifetime. The result of MCS identification is combined with CloudSat data products to study the vertical structure of the MCSs at various MCS life stages: developing, mature, and dissipating.

 The distribution of MCSs in Indonesia has a seasonal variation and distinct diurnal cycle. The life stages of observed MCSs are characterized by distinct cloud microphysics at each stage. In developing stage, the upper level of the MCS raining region shows the presence of precipitating ice particles. As the MCS matures, the proportion of raining area becomes smaller and the intensity of rain is reduced, accompanied by larger occurrence of smaller-sized ice particles at the upper level. In dissipating stage, large hydrometeors no longer exist at the upper part of raining region. Within the MCS anvils, the dissipating stage shows a more uniform distribution of ice-particle effective radius compared to developing and mature stages.

 MCS characteristics over the land and ocean are also clarified to differ on the minimum brightness temperature, the equivalent radius, the maximum rain rate, and the rain fraction which vary along MCS evolution.