Evaluation of NARAD Precipitation Data for Rainfall Monitoring in Eastern Ontario, Canada

Abstract

The development of NEXRAD weather radar products has greatly advanced the capacity to forecast and provide warnings of severe weather conditions over large areas in a time-efficient manner. However, most studies in the literature are conducted within the U.S. This study evaluates the reliability of NEXRAD precipitation data and rain gauge measurements in Eastern Ontario, Canada, for potential flood monitoring and water budget analysis. Five-month daily rainfall data from NEXRAD and rain gauge measurements were collected and generated for two Eastern Ontario conservation authority regions. The NEXRAD data was evaluated using rain gauge measurements as the reference. A good correlation (0.78) exists between the daily NEXRAD precipitation data and rain gauge measurements, especially for heavier rainfalls. The result also shows that 62% of radar precipitation data underestimates the daily precipitation. This underestimate is more common when the rainfall is small. The evaluation of spatial patterns of rainfall suggests that radar precipitation shows a more continuous pattern than the interpolated surfaces from rain gauges. Considering that small rainfall events contribute a relatively small portion of the total precipitation, NEXRAD products can play an important role in real-time flood monitoring and water budget analysis during heavy rainfall events in Canadian regions within the working range distance of the NEXRAD system.