Satellite-derived Sea Surface Temperatures – a Case Study of Error Variability

In situ measurements of skin and bulk sea surface temperatures have been obtained during a cruise of the RV Southern Surveyor during June 2006. Comparisons with satellite-derived estimates of SST show error variability that may lead to a better understanding of the role of the ocean surface and atmospheric conditions in contributing to the in situ/satellite differences. During the first half of the cruise the satellite estimates from AVHRR tended to be hotter than the in situ measurements while the reverse was the case for the latter half of the cruise. For AMSR-E on the AQUA satellite the estimates at night were in many cases warmer than the ship measurements while the daytime estimates were more accurate. AATSR gave measurements that were close to both the thermosalinograph and a ship-borne infrared radiometer. Measurements of total water vapour column from AMSR-E data and near-surface relative humidity suggest that the AVHRR anomalies are related to vertical water vapour structure in the lower atmosphere. This supports earlier theoretical work reported at the Salzburg ENVISAT Symposium in 2004 and demonstrates the possibility of reducing errors in the SST derivation from AVHRR and other nadir-viewing satellite instruments such as MODIS.