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Precipitation Responses Following Abrupt Changes in Land Surface Characteristics

Authors: Shannon Alexis Nelson*, Louisiana State University, Paul W. Miller, Louisiana State University
Topics: Climatology and Meteorology
Keywords: Hydroclimate, Disturbance Hydrology, Hurricane
Session Type: Paper
Presentation File: No File Uploaded

Defoliation, a reduction in green leaves and mature vegetation, alters moisture and energy budgets that drive the local water cycle by reducing evapotranspiration (ET). Landfalling hurricanes can quickly induce severe defoliation and reduced ET, possibly redistributing precipitation near the storm’s path. Research has engaged similar environmental impacts over longer, climatological time scales, but less work has examined hydrological responses in the seasonal-to-annual scale following a strong hurricane. Understanding the nature of these more immediate hydrological consequences is important for recovery efforts for those in vulnerable, hard-hit regions. This project will compare the frequency and spatial distribution of observed pre- versus post-hurricane precipitation activity and investigate the driving physical mechanisms through a numerical weather simulation using the Weather Research and Forecasting (WRF) model version 3.8. Post-hurricane water cycle responses (ET, precipitation) to altered land surface conditions will be identified over parts of Florida and Georgia after Hurricane Michael, which delivered maximum winds of 259 km/h (161 mph) during landfall on October 10, 2018. Michael’s substantial wind defoliated an estimated area spanning 13,000 km2 (3 million acres). A control simulation assimilated with normal vegetation conditions will be compared against an experimental simulation initialized with observed post-Michael vegetation. Ground-truthing model outputs to measured precipitation will validate the model parameterization selections. By evaluating the magnitude and duration of any precipitation enhancement/reductions, this study will assess modified local water cycle patterns for the time period following an abrupt disturbance event. Results from this study will highlight the role of surface vegetation on precipitation.

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