Multiscale interactions of tropical convection in the Indian Ocean

Deanna A. Hence
Assistant Professor, University of Illinois Urbana-Champaign 

Two high-impact weather phenomena form regularly in the Indian Ocean basin: tropical cyclones (TCs), and the convectively-active component of the Madden-Julian Oscillation (MJO). The MJO is one of the key seasonal modulators of precipitation for the equatorial Indian Ocean, Maritime Continent, and the west Pacific Ocean. Although less frequent than the other tropical cyclone basins of the world, the impacts of TCs making landfall in this region are legendary, given the highly populous countries that ring the basin. 

Our work began with using the MJO as a means to understand how differences in the larger-scale flow can influence the structure and evolution of tropical oceanic deep convection. As tropical cyclones often form within the vicinity of the active phase of the MJO, this study led to an additional question: how can these two phenomena influence each other? Using a combination of case analysis of an active MJO during the DYNAMO field campaign alongside statistical analysis of best track and ERA5 reanalysis data of tropical cyclones coinciding with the convectively-active phase of the MJO in the Indian Ocean, we examine how the presence of TCs in the basin may influence the westerly wind burst (WWB), a zone of anomalously westerly equatorial winds that follows the MJO’s convective envelope. Our results indicate possible implications for moisture convergence and precipitation at scales much larger than the TC circulation itself.

This talk is presented as a Zoom Webinar. For anyone outside the department; If you would like to attend, email [email protected]

Topic: Deanna Hence Colloquium 
Date: Oct 7, 2020
Time: 3;30-4:30 PM Eastern Time (US and Canada)

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