The tropical atmosphere exhibits significant variability at intraseasonal (~30-80 day) timescales. During boreal summer, propagating intraseasonal modes produce locally rainy and dry periods within the South Asian monsoon. The Madden-Julian Oscillation (MJO) dominates intraseasonal variability during boreal winter, with areas of enhanced convection propagating from the Indian Ocean eastward over the Maritime Continent and Pacific.
Mesoscale convective systems (MCSs) are important members of the tropical cloud population, producing a large proportion of tropical rainfall as well as major flooding, hail, and strong winds. In this study, MCSs are identified using A-Train satellite observations of their raining cores and extensive cold cloud shields. Variations in MCS vertical structure and lightning production are examined during the evolution of intraseasonal modes over the South Asian monsoon and MJO regions, using radar reflectivity profiles from CloudSat and lightning observations from a ground-based detection network. Parallels in MCS behavior in the monsoon and MJO contexts illustrate the fundamental control of convective and mesoscale behavior by the large-scale environment.
613 Seminar Series Coordinators