Disclaimer: This material is being kept online for historical purposes. Though accurate at the time of publication, it is no longer being updated. The page may contain broken links or outdated information, and parts may not function in current web browsers. Visit espo.nasa.gov for information about our current projects.

 

Observed and Simulated Upper-Tropospheric Water Vapor Feedback

The core information for this publication's citation.: 
Gettelman, A., and Q. Fu (2008), Observed and Simulated Upper-Tropospheric Water Vapor Feedback, J. Climate, 21, 3282-3289, doi:10.1175/2007JCLI2142.1.
Abstract: 

Satellite measurements from the Atmospheric Infrared Sounder (AIRS) in the upper troposphere over 4.5 yr are used to assess the covariation of upper-tropospheric humidity and temperature with surface temperatures, which can be used to constrain the upper-tropospheric moistening due to the water vapor feedback. Results are compared to simulations from a general circulation model, the NCAR Community Atmosphere Model (CAM), to see if the model can reproduce the variations. Results indicate that the upper troposphere maintains nearly constant relative humidity for observed perturbations to ocean surface temperatures over the observed period, with increases in temperature ϳ1.5 times the changes at the surface, and corresponding increases in water vapor (specific humidity) of 10%–25% °CϪ1. Increases in water vapor are largest at pressures below 400 hPa, but they have a double peak structure. Simulations reproduce these changes quantitatively and qualitatively. Agreement is best when the model is sorted for satellite sampling thresholds. This indicates that the model reproduces the moistening associated with the observed uppertropospheric water vapor feedback. The results are not qualitatively sensitive to model resolution or model physics.

PDF of Publication: 
Download from publisher's website.
Research Program: 
Atmospheric Composition Modeling and Analysis Program (ACMAP)
Modeling Analysis and Prediction Program (MAP)