Tracking the shape change of tropical cyclone precipitation in gridded observational data

Authors: Yao Zhou*, University of Central Florida, Corene Matyas, University of Florida
Topics: Climatology and Meteorology, Geographic Information Science and Systems
Keywords: tropical cyclones, precipitation, GIS, statistical modelling
Session Type: Paper
Day: 4/3/2019
Start / End Time: 12:40 PM / 2:20 PM
Room: Stones Throw 1 - Granite, Marriott, Lobby Level
Presentation File: No File Uploaded

The accurate detecting and quantifying the spatial pattern of tropical cyclone precipitation (TCP) can improve forecasts. The goal of this study is to examine changes in the spatial pattern of TCP before and after landfall. Precipitation features associated with tropical cyclones (TCs) landfalling over western North Atlantic coast are created by tracking 3-hourly observed rainfall in the TRMM 3B42 and IMERG data sets. We develop a revised centroid-based tracking algorithm that considers TC size, storm movement, overlap area, and centroid distance of precipitation features. Sensitivity analysis of the tracking algorithm to the rain rate, minimum rainfall area, and overlap threshold is discussed. For each TC, we identify five events in precipitation feature topology: generation, continuity, split, merger, and dissipation. The spatial pattern is quantified using a variety of shape metrics, including elongation, roundness, fragmentation, dispersion, displacement, and solidity. Trend analysis is applied to identify the significate change in rainfall shape metrics over multiple moving windows ranging from 21-48 hours. Non-parametric methods and regressions are used to link the TC attributes and environmental conditions to changes in rainfall topology and shape metrics. The results show that the roundness has higher significant increasing trends over southeastern Gulf, Florida, and the central Caribbean Sea, while more increasing trends in elongation of a continuous rainfall feature occur over the ocean adjacent to Georgia and the Carolinas and/or during the extratropical transition. Dispersion and fragmentation increase with new features generation as TCs approach coastline, while fragmentation decreases as TCs move inland and rainfall dissipates.

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