Extended Abstract (332K)3.4
Synergisms and comparisons between airborne Doppler Wind Lidar observations and other remote and in-situ wind measurements and model forecasts
Steven Greco, Simpson Weather Associates, Charlottesville, VA; and G. D. Emmitt, S. A. Wood, C. O'Handley, and H. Jonsson
For the past six years, Simpson Weather Associates (SWA) has utilized a unique airborne Doppler Wind Lidar (DWL) operated by the Navy's Center for Interdisciplinary Remotely Piloted Research Studies (CIRPAS) to study the atmosphere, the surface and the environment along and off the coast near Monterey, CA. More than 100 hours of flight time have been flown with most of that over the Pacific Ocean and within 50 km of the shore. The two most recent field campaigns took place in April and November of 2007.
The Twin Otter Doppler Wind Lidar (TODWL), which has been flown on the Navy Twin Otter aircraft since 2002, includes a laser beam that is directed by a two-axis scanner mounted in a side door. From this location, the TODWL can perform upward conical scans, downward conical scans, point-aheads and nadir dwells. Complete wind profiles below flight level can be obtained each 250 m of flight path. The vertical resolution of u, v and w components of the wind is ~ 50 m. The lowest level at which wind observations can be made is ~ 25-50 m above the surface. SWA has developed software, scanning strategies and data processing algorithms that have resulted in highly accurate wind observations (< .05 m/s for LOS and < .10 m/s for u, v, and w components). These DWL wind observations have been used to study the boundary layer circulations over the water as well as inland over complex terrain. In addition to winds, the TODWL system also can map aerosol structures/features (with a resolution < 5 meters in some instances) and thus provide information on the depth of the boundary layer , the vertical extent of the ocean spray zone, and the organization of aerosols and the presence of foam on the ocean surface.
Comparisons are made between the TODWL wind observations and winds measured by rawinsondes, microwave wind profilers, and buoys over the Monterey Bay. In addition, comparisons between the TODWL observation and MM5 forecasted profiles will also be presented and discussed. Special emphasis will be placed on those cases where there are discrepancies between the various observing platforms as well as between the observations and models.
By combining wind and aerosol data, the TODWL has also provided unique observations of Organized Large Eddies (OLE) over the open ocean. In the course of conducting flights, the TODWL has underflown WindSat and QuikScat on several occasions by chance and, on numerous occasions, by design. The most recent and planned underflight took place in April 2007. Comparisons are being made between the ocean vector winds from QuikSCAT and WindSat and the co-located TODWL wind profiles. Analysis of the circulations and investigation of the discrepancies between observations will be presented. Preliminary review of the Quikscat and WindSat products suggests large discrepancies on several occasions.
Session 3, Atmospheric Observations for Weather and Climate-III
Monday, 21 January 2008, 1:30 PM-2:30 PM, 204
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