Intercomparison of Aircraft and Surface Buoy Meteorological Data during CODE-1

Abstract

Intercomparisons of meteorological data—wind speed and direction, surface temperature and surface pressure—were obtained for NCAR Queen Air overflights of four buoys during the CODE-1 experiment. The overflights were at a nominal altitude of 33 m. Wind and air temperature sensors were at 10 m on two National Data Buoy Office (NDBO) buoys and at 3.5 m on two Woods Hole Oceanographic Institution (WHOI) buoys. The buoy wind speeds were adjusted to the aircraft altitude using diabatic flux-profile relations and bulk aerodynamic formulas to estimate the surface fluxes and stability. For the experimental period (22 April-23 May 1981) and location (northern coast of California), the atmospheric surface layer was generally stable, with the Monin-Obukhov length on average 500 m with large variability. The results of the intercomparisons of the above variables were in general good. Average differences (aircraft - buoy) and standard deviations were +0.1 m s⁻¹ (±1.8) for wind speed, 3.3 deg (±11.2) for wind direction, +0.02°C (±1.7) for air temperature and +0.8 mb (+1.0) for surface pressure. The aircraft downward-looking infrared radiometer indicated a surface temperature 1°C lower than the buoy hull (NDBO) and 1 m immersion (WHOI) sea temperature sensors.