Evidence of possible sea-ice influence on Microwave Sounding Unit tropospheric temperature trends in polar regions

Spencer and Christy have analyzed data derived from the Microwave Sounding Unit (MSU) series of satellite instruments to assess climate change. This report presents data which suggests a source of error in their MSU/AMSU TLT product. A comparison of data for high latitudes in the Southern Hemisphere demonstrate that the TLT product does not represent the seasonal cycle of temperature in the lower troposphere, as seen in radiosonde data from Antarctica. The difference appears to be the result of the yearly sea‐ice cycle, thus trends in the sea‐ice cycle may impact the TLT product. The Arctic data could also be influenced. These observations question of the validity of the TLT product as a measure of climate change at high latitudes.