Improving RUC-1 wind estimates by incorporating near-real-time aircraft reports

A verification study of wind accuracy is presented for wind nowcasts genera ted by augmenting Rapid Update Cycle (RUC) wind forecasts with near-real-ti me aircraft reports using the Integrated Terminal Weather System (ITWS) gri dded winds algorithm. Aircraft wind reports collected between the end of th e RUC data collection interval and the time each RUC forecasts is valid are available for use in augmenting the RUC wind forecast to form a wind nowca st. The 60-km resolution, hourly RUG-I wind forecasts are used. ITWS-based nowcast wind errors and RUC forecast wind errors are examined st atistically over a 1-yr dataset. The addition of the recent aircraft report s significantly reduces therms vector error and the 90th percentile vector error. Also reduced is the number of hours of sustained large errors and th e correlation among errors. The errors increase with increasing wind speed, in part due to an underestimation of wind speed that increases with increa sing wind speed. The errors in the augmented wind fields decrease with incr easing numbers of Aircraft Communications Addressing and Reporting System r eports. Different types of weather are also seen to influence wind field ac curacy.