Resolving discrepancies between MSU estimates of the tropical tropospheric temperature trend
Abstract
Three independent groups (NOAA STAR, UAH, and RSS) have constructed long-term temperature records for the troposphere using the polar orbiting microwave sounding unit (MSU), but these groups disagree on the magnitude of the trend since 1979. This is especially true over the tropics where the tropospheric temperature trend from UAH is smaller than the NOAA and RSS trends. In particular, the tropical tropospheric temperature trend from UAH is smaller than the observed surface trend, while NOAA and RSS show enhanced warming compared to the surface. These discrepancies result from different satellite calibration methods, which can lead to "jumps" or discontinuities in the temperature time series. For example, different methods for removing the "instrument body effect" can account for a large fraction of the trend differences. The diurnal adjustments for drifts in the local equatorial crossing time, which are large in the tropics, can also lead to spurious trends. Understanding the effects of dislocations and drifts in the temperature time series can help explain differences between the three satellite-derived estimates of the tropical tropospheric temperature trend. We attempt to assess the impact of jumps and spurious trends on the various satellite datasets using radiosonde data in order to constrain the tropical tropospheric temperature trend. This effort is important for understanding and testing global circulation models that predict that the tropical troposphere will warm more than the surface.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFM.A51A0130P
- Keywords:
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- 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0325 ATMOSPHERIC COMPOSITION AND STRUCTURE / Evolution of the atmosphere;
- 1610 GLOBAL CHANGE / Atmosphere;
- 1640 GLOBAL CHANGE / Remote sensing