INTERCOMPARISON OF AIRCRAFT AND BUOY MEASUREMENTS OF WIND AND WIND STRESS DURING SMILE

An intercomparison between low-level aircraft measurements of wind and wind stress and buoy measurements of wind and estimated wind stress w as made using data collected over the northern California shelf in the Shelf Mixed Layer Experiment (SMILE). Twenty-five buoy overflights we re made with the NCAR King Air at a nominal altitude of 30 m over NOAA Data Buoy Center (NDBC) environmental buoys 46013 and 46014 between 1 3 February and 17 March 1989; meteorological conditions during this pe riod were varied, with both up- and downcoast winds and variable stabi lity. The buoy winds measured at 10 m were adjusted to the aircraft al titude using flux profile relations, and the surface fluxes and stabil ity were estimated using both the TOGA COARE and Large and Pond bulk p arameterizations. The agreement between the King Air wind speed and di rection measurements and the adjusted NDBC buoy wind speed and directi on measurements was good. Average differences (aircraft - buoy) and st andard deviations were 0.6 +/- 0.8 m s(-1) for wind speed and 0.0 degr ees +/- 10.5 degrees for direction (adjusted for buoy offset), indepen dent of parameterization used. The comparisons of aircraft and buoy wi nd stress components also showed good agreement, especially at larger values of the wind stress (>0.1 Pa) when the wind stress field appeare d to be more spatially organized. For the east component, the average difference and standard deviation were 0.018 +/- 0.029 Pa using TOGA C OARE and -0.018 +/- 0.027 Pa using Large and Pond. For the north compo nent, the average difference and standard deviation are 0.003 +/- 0.01 8 Pa using TOGA COARE and 0.003 +/- 0.017 Pa using Large and Pond. The se results support the idea that low-flying research aircraft like the King Air can be used to accurately map both the surface wind and the surface wind stress fields during even moderate wind conditions.