Simultaneous airborne measurements of sea surface temperature (SST) by an infrared (IR) radiometer and radar backscatter from a scattcromcter operating at the same C band as on ERS-1, were made over the Tyrrhenian Sea. The aircraft SST field showed part of the cold and warm eddy system characteristic of the region and compared well with ship-based measurements. The radar backscatter data were examined to investigate whether any dependence on SST could be discerned. It was found that the radar backscatter data gave a more intermittent view of the eddy and that view appeared to change from day to day. A change in the radar view of the eddy could occur due to changing wind fields or atmospheric stability patterns over the thermal front and this hypothesis was discussed with regard to two periods with different atmospheric conditions. For two days of very light winds and calm sea conditions the radar signature followed the main thermal gradient features and a positive, significant correlation was obtained between the SST and radar spatial patterns. For a further three days with moderate winds from the north to east quarter, a negative and generally weakening correlation was obtained with SST, with the radar view not identifying the major thermal gradients associated with the eddy.