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Evolution of Drop Size Distributions during Hurricane Harvey
and Their Effects on Rain Intensity
Hurricane Harvey hit the Texas Gulf Coast as a major hurricane on August 25, 2017, before exiting the state as a tropical storm on August 29, 2017. Left in its wake was historic flooding over southeast Texas with some locations measuring more than 60 inches of rain. The Houston NEXRAD radar (KHGX) maintained operations for the entirety of the event and is utilized in this study to better understand the evolution of the drop size distribution (DSD) in the lower (liquid) portions of the storm and how changes in the DSD were tied to observed and measured changes in rain intensities. From the KHGX dual-polarimetric radar data several DSD parameters were retrieved, including three different rain rate retrievals, as well as the mass-weighted mean-drop diameter Dm, and the normalized intercept parameter NW of the gamma distribution. Two of the rain retrievals are popular hybrid approaches, where reflectivity, differential and specific differential phase are used. The other is an attenuation-based retrieval. In a previous study, it was found that both hybrid retrievals significantly underestimated the rainfall during the heaviest rain periods, while the attenuation-based retrieval, with proper adjustment, agreed quite well with a large network of gauges from the Harris County Flood Warning System. Using Dm and NW as proxies for drop size and concentration, respectively, we will show that the heaviest rain intensities were associated in areas of the storm where there was a large concentration of large drops present. It is envisaged that results of this study can be used to develop a near-real-time tuning of the attenuation-based retrieval, thus providing timely, and possibly life-saving warnings during inundating rainfall.
Document ID
20210020253
Acquisition Source
Goddard Space Flight Center
Document Type
Presentation
Authors
David B. Wolff
(Wallops Flight Facility Wattsville, Virginia, United States)
David A. Marks
(Science Systems & Applications, Inc. Hampton, VA, USA)
Ali Tokay
(University of Maryland, Baltimore County Baltimore, Maryland, United States)
Jason L. Pippitt
(Science Systems and Applications (United States) Lanham, Maryland, United States)
Date Acquired
August 9, 2021
Subject Category
Earth Resources And Remote Sensing
Meeting Information
Meeting: 2021 American Geophysical Union Meeting Fall Meeting
Location: New Orleans, LA
Country: US
Start Date: December 13, 2021
End Date: December 17, 2021
Sponsors: American Geophysical Union
Funding Number(s)
WBS: 378289.04.05.05
Distribution Limits
Public
Copyright
Public Use Permitted.
Technical Review
Single Expert
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