Comparison of NEXRAD and Rain Gauge Precipitation Measurements in South Florida
Publication: Journal of Hydrologic Engineering
Volume 14, Issue 3
Abstract
The South Florida Water Management District (SFWMD) relies on a network of nearly 300 rain gauges in order to provide rainfall data for use in operations, modeling, water supply planning, and environmental projects. However, the prevalence of convective and tropical disturbances in South Florida during the wet season presents a challenge in that the current rain gauge network may not fully capture rain events that demonstrate high spatial variability. Next Generation Radar (NEXRAD) technology offers the advantage of providing a spatial account of rainfall, although the quality of radar-rainfall measurements remains largely unknown. The comparison of rainfall estimates from a gauge-adjusted, NEXRAD-based product developed by the OneRain Company with precipitation measurements from SFWMD rain gauges was performed for the Upper and Lower Kissimmee River Basins over a four-year period from 2002 to 2005. Overall, NEXRAD was found to underestimate rainfall with respect to the rain gauges for the study period, demonstrating a radar to gauge ratio of 0.95. Further investigation of bias revealed the tendency for NEXRAD to overestimate small rainfall amounts and underestimate large rainfall amounts relative to the gauge network. The nature of bias present in the data led to the development of a radar-rain gauge relationship to predict radar precipitation estimates as a function of rain gauge measurements. The intent of this paper is to demonstrate the importance of identifying systematic offsets which may be present in radar-rainfall data before application in hydrologic analysis.
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Acknowledgments
The writers appreciate the contribution of several individuals including Steve Hill, Scott Huebner, Greg Shaughnessy, and Eric Swartz of the SFWMD, as well as David Curtis, Lou Torrence, and Baxter Vieux. The writers would also like to acknowledge the SFWMD for funding this study, as well as the reviewers for providing insightful comments to help improve this work.
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Information & Authors
Information
Published In
Journal of Hydrologic Engineering
Volume 14 • Issue 3 • March 2009
Pages: 248 - 260
Copyright
© 2009 ASCE.
History
Received: Feb 18, 2007
Accepted: May 30, 2008
Published online: Mar 1, 2009
Published in print: Mar 2009
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