Journal of Climate, 23, 4556-4570.

Diagnosis of zonal mean relative humidity changes in a warmer climate


Jonathon Wright
Department of Applied Physics and Applied Mathematics, Columbia University, New York, NY.

Adam H. Sobel
Department of Applied Physics and Applied Mathematics and Department of Earth and Environmental Sciences, Columbia University, New York, NY.

Joseph Galewsky
Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, NM.


Abstract

The zonal mean relative humidity response to a doubling of CO2 in a climate model is examined, using two different methods to differentiate the effects of circulation changes from spatially inhomogeneous temperature changes. The tropical and subtropical response are found to be largely dependent on circulation changes, particularly a poleward expansion and deepening of the Hadley circulation, a poleward shift of the extratropical jets, and an increase in the height of the tropopause. The responses near the extratropical tropopause and in the lower troposphere are largely dependent on changes in the distribution and gradients of temperature.The zonal mean relative humidity response to a doubling of CO2 in a climate model is examined, using two different methods to differentiate the effects of circulation changes from spatially inhomogeneous temperature changes. The tropical and subtropical response are found to be largely dependent on circulation changes, particularly a poleward expansion and deepening of the Hadley circulation, a poleward shift of the extratropical jets, and an increase in the height of the tropopause. The responses near the extratropical tropopause and in the lower troposphere are largely dependent on changes in the distribution and gradients of temperature.