AIR TRUTH VALIDATION OF CLOUD ALBEDO ESTIMATED FROM NOAA ADVANCED VERY HIGH-RESOLUTION RADIOMETER DATA

A comparison was carried out between cloud albedos observed in situ by aircraft and cloud albedos calculated with visible optical thickness retrieved from the NOAA advanced very high resolution radiometer channel 1 radiance data. The results show that the observed and calculated cloud albedos in the visible region are coincident with each other in a few percent for both homogeneous stratus and rather inhomogeneous stratocumulus clouds as long as the cloud amount is large. In the near-infrared region, on the other hand, the observed albedo is lower than that evaluated from the satellite data for stratocumulus clouds, while the observed and calculated albedos are consistent for stratus clouds. From the aircraft observation of solar radiative flux this discrepancy is not ascribed to the uncertainty in the near-infrared absorption processes as discussed in previous studies.