A comparison of ground-based Doppler lidar and airborne in situ wind observations above complex terrain

Airborne wind observations collected by the National Oceanic and Atmospheric Administration's (NOAA) WP-3D aircraft are compared with the winds retrieved by the NOAA/Environmentai Technology Laboratory's ground-based scanning Doppler lidar within the Wipp Valley during the Special Observing Period of the Mesoscale Alpine Programme. Comparisons are performed along individual flight tracks and over an aggregated dataset consisting of all pairs of WP-3D and lidar observations that were approximately coincident in time and space. The impact of several different quality-control thresholds on the root mean square (r.m.s.) difference between the two observations is explored. The overall quality-controlled r.m.s. difference between radial wind speeds measured by each platform was 3.0 m s(-1), with larger r.m.s. errors in the region up valley from the lidar than in the region down valley. A bias was also evident, in which the wind speeds from the WP-3D exceeded those from the lidar; this bias was small down valley (0.4 m s(-1)) and much larger up valley (2.4 m s(-1)).