Understanding the evolution of storms embedded in MCSs and associated three-dimensional structures using remote sensing observations

Mesoscale convective systems (MCS) are the largest type of deep convective storms and are important as they account for a large fraction of precipitation in the tropics, cause severe weather, and influence the larger-scale circulation. During the Indian summer monsoon (June-September), synoptic-scale weather systems forming over the head Bay of Bengal and moving north-west across the monsoon zone are responsible for frequently initiating MCSs. MCSs often produce widespread and heavy rain across the monsoon zone which is largely dependent on rainfall as a primarily farming society. The studies on structure and evolution of MCSs highlighting the organization of convection over the monsoon zone are lacking.
The MCSs can be categorized into leading-line/trailing stratiform and disorganized structures based on the arrangement of storms within them. Thus, the storms play an important role in MCS organization. Here, we focused on the evolution of internal structures of MCSs over their life cycle. A high spatio-temporal S-band Doppler weather radar data collected within the monsoon zone is used to explore 3-D structures of storms embedded in MCSs and how it relates to the MCS life cycle. First, a cloud-tracking algorithm is applied to geostationary satellite infrared brightness temperature and GPM IMERG precipitation to identify and track individual MCS events during monsoon 2014-2017. For the observed MCSs over a radar domain, we defined the embedded storm structure by applying a storm classification method to radar data. Storm classification provided each grid column with radar echoes into 5 categories namely convective, precipitating stratiform, non-precipitating stratiform, anvil, and convective updraft. 
We observed that an MCS contain multiple precipitation features, particularly during the initial development stage when multiple convective clusters begin to aggregate. Further, we examined the time series of co-evolution of storm properties (e.g., areas of convective/stratiform precipitation, convective core length, and convective core echo top heights). During the convective initiation and MCS genesis stages, the convective feature is most intense and largest, as evidenced by the deepest convective feature echo-top heights and the largest horizontal dimensions. Having identified different storms that are embedded in MCS, we applied a technique of Contoured frequency-by-altitude diagram (CFADs) to investigate the depth and internal vertical structure of storms and to show how ensemble properties of the group of storms evolve. Distinct structures of CFADs are observed. The statistics of the evolution of 3-D storm structures for all identified MCS cases will be presented and discussed at the conference.