Friday, August 12, 2005
Three Science reports (online, not yet published) address weather probe/satellite data previously interpreted to show cooling of the troposphere in the Tropics (rather than the expected warming) during the last two decades. This data had led to some to question the validity of current climate models because tropospheric warming should accompany surface warming.
The reports all address different aspects of the problem,
but all three indicate the troposphere is warming,
not cooling, and current climate change models are sound.
Santer et al conclude that the models have excellent agreement with observed surface and tropospheric temperatures on the monthly and annual time scales. Partial agreement with observed tropospheric temperatures over the decadal timescale together with empirical evidence of increases in tropospheric water vapor and tropopause height
suggest warming, not cooling, of the free troposphere.
Link: Santer, et al abstract -
Amplification of Surface Temperature Trends
and Variability in the Tropical Atmosphere
Mears and Wentz correct the satellite data for biases caused by satellite angle and diurnal cycle (time of day). Based on their correction method, global tropospheric temperatures are increasing at roughly .193 K per decade instead of .087 K per decade previously estimated;
tropical tropospheric temperatures are increasing at 9 K per decade instead of the slight cooling estimated using a different correction method. Mears and Wentz Abstract
Sherwood, Lanzante, and Meyer report that the bias caused by solar heating (time of day or diurnal cycle) has lessened over time, even though
corrections made to account for that bias have not. Taking this into account, they calculated a .14 C warming per decade in the tropical troposphere, rather than cooling.
Sherwood, Lanzante, and Meyer abstract