Sensitivity of simulated climate to two atmospheric models: Interpretation of differences between dry models and moist models

Authors:

HE ZHANG
ICCES, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
MINGHUA ZHANG
ICCES, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China, and School of Marine
and Atmospheric Sciences, Stony Brook University, Stony Brook, New York
QING-CUN ZENG
ICCES, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China

Abstract：

The dynamical core of the Institute of Atmospheric Physics of the Chinese Academy of Sciences Atmospheric General Circulation Model (IAP AGCM) and the Eulerian spectral transform dynamical core of the Community Atmosphere Model (CAM3.1) developed at the National Center for Atmospheric Research (NCAR) are used to study the sensitivity of simulated climate. We report that when the dynamical cores are used with the same CAM3.1 physical parameterizations and with comparable resolutions, the model with the IAP dynamical core simulated a colder troposphere than that from the CAM3.1 core, reducing the CAM3.1 warm bias in the troposphere in the tropics and middle latitudes. However, when the two dynamical cores are used in the idealized Held-Suarez tests without moisture physics, the IAP AGCM core simulated a warmer troposphere than that in CAM3.1. The causes of the differences in the full models and in the dry models are then investigated. We show that the IAP dynamical core simulated weaker eddies in both the full physics and the dry models than those in the CAM due to different numerical approximations. In the dry IAP model, the weaker eddies cause smaller heat loss from poleward dynamical transport and thus warmer troposphere in the tropics and middle latitudes. When moist physics is included, however, weaker eddies also lead to weaker transport of water vapor and reduction of high clouds in the IAP model, which then causes a colder troposphere due to reduced greenhouse warming of these clouds. Our results show how interactive physical processes can change the effect of a dynamical core on climate simulations between two models.

Key words：

AGCM, dynamical core, dry models, moist models

Citation:

F Zhang et al.Sensitivity of simulated climate to two atmospheric models: Interpretation of differences between dry models and moist models.Environ. Res. Lett. 9 (2014) 075002 (14pp) doi:10.1088/1748-9326/9/7/075002