Comparisons of aircraft, ship, and buoy radiation and SST measurements from TOGA COARE

Mean radiative fluxes and sea surface temperature measured by the five Tropical Ocean-Global Atmosphere Coupled Ocean-Atmosphere Response Experiment (TOGA COARE) boundary layer research aircraft were compared with each other and with surface measurements from moored buoys and ships. The basic data-processing techniques for radiative flux and sea surface temperature (SST) measurements from an aircraft were reviewed, and an empirical optimisation method to calibrate an Eppley pyrgeometer was introduced. On the basis of aircraft wingtip-to-wingtip comparison periods, the processed aircraft downwelling shortwave and longwave irradiance and SST measurements were found to agree to 28+/-18 W m(-2), 9+/-4 W m(-2), and 0.7+/-0.4 degrees C, respectively. By using the same comparison periods, empirical corrections that removed systematic errors in the aircraft data were determined. Application of these corrections improved the wingtip comparison accuracy to 3+/-16 W m(-2), 1+/-4 W m(-2), and 0.1+/-0.3 degrees C, respectively. Comparisons between the (fully corrected) aircraft and the surface platform measurements revealed the aircraft data to be slightly greater for all three parameters. The agreement was around 3+/-37 W m(-2), 3+/-6 W m(-2), and 0.3+/-0.5 degrees C for shortwave irradiance, longwave irradiance, and SST, respectively. (Detailed comparison results were provided for each individual ship and buoy.) After applying the aircraft Empirical corrections the level of accuracy was near the COARE objectives.