A33P-06
Upper Tropospheric Water Vapor and Cloud Variations with Sea Surface Temperature in Observations and Models
Wednesday, 16 December 2015: 14:55
3008 (Moscone West)
Hui Su1, Jungmin Park2, Tsae-Pyng J Shen1, Jonathan H. Jiang1, Yong-Sang Choi3, Chengxing Zhai1 and Lei Huang1, (1)NASA Jet Propulsion Laboratory, Pasadena, CA, United States, (2)Ewha Womans University, Seoul, South Korea, (3)Ewha Womans University, Atmospheric Science and Engineering, Seoul, South Korea
Abstract:
Upper tropospheric water vapor and clouds (UTWVC) are critical to global radiative balance. The UTWVC variations with sea surface temperature (SST) are important components for climate feedbacks. In particular, the iris effect hypothesized by Lindzen et al. (2001) highlights that the radiative role of UTWVC is effective in relieving global warming. The iris effect and its implication for climate sensitivity and hydrological change (Mauritsen and Stevens 2015) center on the sign and magnitude of UTWVC with SST. We assess the UTWVC variations with SST using satellite observations and model simulations. The nearly 30-year observations of high cloud from the International Satellite Cloud Climatology Project and the over 10-year observations of UT water vapor, cloud and radiative fluxes from NASA’s A-Train satellites are examined, in comparison with the counterparts in 14 CMIP5 models. We find that models underestimate the increase of outgoing longwave radiation with increasing SST compared to the observations, and this behavior is linked to the modeled UTWVC variations with SST. Across the 14 models, the ones with weaker iris effect tend to have higher equilibrium climate sensitivity.
