Urban flash flood applications of high-resolution rainfall estimation by X-band dual-polarization radar network

Flooding in general, especially the urban flash flooding is one of the most destructive nature hazards. Rainfall estimates from radar network are often used as input to various hydrological models for further flood warning and mitigations. The X-band dual-polarization radar network developed by the United States National Science Foundation Engineering Research Center (NSF-ERC) for Collaborative Adaptive Sensing of the Atmosphere (CASA) has shown great improvement to radar based Quantitative Precipitation Estimation (QPE), through many years of experimental validation studies. QPE and rainfall nowcasting are important goals of CASA X-band dual-polarization radar networks. This paper presents an overview of CASA QPE and nowcasting methodology. In addition, 20 rainfall events collected from the Oklahoma test best during the past 3 years are used to evaluate the networked radar rainfall products. Cross validation with a gauge network using these 20 events’ data shows that the estimates of instantaneous rain rate, 5-minute,10- minute, and hourly rainfall have normalized standard error of about 47.57%, 40.03%, 34.61% and 24.78% , respectively, whereas a low bias of about -3.83%, -2.83%,-2.77% and -3.45% respectively. These evaluation results demonstrate great improvement compared to the current state-of-the-art. The paper also deals with the potential role of these highresolution rainfall products for flash floods warning and mitigation.

[1]  V. Chandrasekar,et al.  High resolution rainfall mapping in the Dallas-Fort Worth urban demonstration network , 2012, 2012 IEEE International Geoscience and Remote Sensing Symposium.

[2]  David J. McLaughlin,et al.  Collaborative Adaptive Sensing of the Atmosphere: New Radar System for Improving Analysis and Forecasting of Surface Weather Conditions , 2006 .

[3]  V. Chandrasekar,et al.  Polarimetric Doppler Weather Radar: Principles and Applications , 2001 .

[4]  V. Chandrasekar,et al.  Nowcasting Rainfall Fields Derived from Specific Differential Phase , 2012 .

[5]  V. Chandrasekar,et al.  The CASA Nowcasting System , 2011 .

[6]  V. Chandrasekar,et al.  Dual‐Polarization Radar Rainfall Estimation , 2013 .

[7]  Alexander V. Ryzhkov,et al.  Advantages of Rain Measurements Using Specific Differential Phase , 1996 .

[8]  George H. Leavesley,et al.  Prediction of a Flash Flood in Complex Terrain. Part II: A Comparison of Flood Discharge Simulations Using Rainfall Input from Radar, a Dynamic Model, and an Automated Algorithmic System , 2000 .

[9]  V. Chandrasekar,et al.  Algorithm for Estimation of the Specific Differential Phase , 2009 .

[10]  J. Gourley,et al.  Evolving Multisensor Precipitation Estimation Methods: Their Impacts on Flow Prediction Using a Distributed Hydrologic Model , 2011 .

[11]  V. Chandrasekar,et al.  Short wavelength technology and the potential for distributed networks of small radar systems , 2009, 2009 IEEE Radar Conference.

[12]  V. Chandrasekar,et al.  The CASA quantitative precipitation estimation system: a five year validation study , 2012 .

[13]  Lawrence D. Carey,et al.  Mesoscale and Radar Observations of the Fort Collins Flash Flood of 28 July 1997 , 1999 .

[14]  Y. Hong,et al.  Impacts of Polarimetric Radar Observations on Hydrologic Simulation , 2010 .

[15]  Philip B. Bedient,et al.  Assessing urban hydrologic prediction accuracy through event reconstruction , 2004 .