Sea Surface Temperature (SST)

Sea surface temperature (SST) is another surface property we are interested in from a meteorological perspective. An IR window in the atmosphere for sensing surface temperature is the 10-12mm region where absorption by water vapor is weak. However, for accurate SST the emission by the atmosphere must be accounted for in the retrieval.

The following figure is a MODerate resolution Imaging Spectrometer (MODIS) 11mm image that clearly indicates changes of SST in the vicinity of the Gulf Stream. Most of the radiation in this band is emitted by the surface and transmitted through the atmosphere. In a warm moist atmosphere the difference between the SST and the brightness temperature at 11mm (BT11) can approach 10° C. This difference is often corrected for by making observations at more than one wavelength, such as 11, 12, 3.7 and 8.5mm. Differences between these channels represent the total amount of water vapor in the column. For example, the 12mm channel has more absorption and therefore (BT11-BT12} is positive; the greater this difference the larger the water vapor loading of the atmosphere. Observations at these wavelengths are used daily to derive SST. The SST from satellite observations is typically determined from a regression derived empirically using observations from drifting buoys.

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