Propagation of Radar-Rainfall Uncertainty in Runoff Predictions.

摘要

This final report documents the results obtained through the final phase of the research study. It consists of two papers that have been submitted for publication based on the research. The objective of this project is to quantitatively evaluate the worth of radar-rainfall estimates for physically based hydrologic modeling. These two papers contain valuable results. To summarize, our study has shown that the physical relationship between radar reflectivity and rainfall rate begins to disappear at a range of approximately 60 km from the radar site for radars with approximately 1 degree bean width. At farther ranges, radar returns are significantly affected by the horizontal and vertical gradients of cloud water. This result was verified through careful testing using a simulation methodology wherein convective rainfall is simulated using the Advanced Regional Prediction Model (ARPs), a radar simulator, and the two dimensional hydrologic model CASC2D. Techniques to correct runoff predictions for likely errors using a Bayesian approach are suggested.