A multi-threshold-based identification and tracking of Mesoscale Convective Systems in a multi-satellite precipitation product

Traditional tracking algorithms use a single threshold in a precipitation or infrared brightness temperature field to identify and track precipitation systems. Though valuable, these algorithms have limitations in tracking Mesoscale Convective Systems (MCSs) that sometimes occur as clusters embedded in synoptic scale disturbances such as tropical and mid-latitude waves. These embedded systems might be connected but should not be identified as a single large system since the connection is transient. The recent detect and spread (DAS) type algorithms help identify an MCS in a cluster  by identifying a core region of heavy rainfall and spreading it into adjacent regions of lower precipitation values. Also, as we move away from a single satellite and towards microsatellite constellations for various meteorological data, we need a robust method to identify and track objects of interest in a multi-satellite product. This is because each satellite in the constellation may have a different sensor that requires cross-calibration and is finally merged to create a single product.

 We present the improved version of the Forward in Time (FIT) tracking program, a multi-threshold, detect and spread type algorithm, to track MCSs in Integrated MultisatellitE Retrievals for Global Precipitation mission (IMERG), NASA's global precipitation product. IMERG is a  multi-satellite precipitation product that combines rain retrievals from passive microwave sensors on a virtual constellation of satellites and rain retrievals from Infrared sensors onboard geostationary satellites. Using the FiT algorithm, we track MCSs in the IMERG precipitation field for ten years (2011-2020) and store MCSs' properties in a publicly available dataset called Tracked IMERG Mesoscale Precipitation Sytems (TIMPS). Leveraging this dataset, we present the regional variability of MCSs properties (frequency, lifetime, and propagation velocity) and some preliminary results from ongoing studies.