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Sensitivity of Precipitation in Aqua-Planet Experiments with an AGCM |
YU Hai-Yang1,2, BAO Qing1, ZHOU Lin-Jiong1,2, WANG Xiao-Cong1, LIU Yi-Min1 |
1State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
2Graduate University of Chinese Academy of Sciences, Beijing 100049, China |
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Abstract The sensitivity of precipitation was studied by conducting control aqua-planet experiments (APEs) with a model to determine atmospheric general circulation. The model includes two versions: that with a spectral dynamical core (SAMIL) and that with a finite-volume dynamical core (FAMIL). Three factors were investigated including dynamical core, time-step length, and horizontal resolution. Numerical results show that the dynamical core significantly affects the structure of zonal averaged precipitation. FAMIL exhibited an equatorial precipitation belt with a single narrow peak, and SAMIL showed a broader belt with double peaks. Moreover, the time step of the model physics is shown to affect the zonal-averaged tropical convective precipitation ratio such that a longer time step leads to more production and consumption of convective available potential energy and convection initiated away from the equator, which corresponds to equatorial double peaks of precipitation. Further, precipitation is determined to be sensitive to horizontal resolution such that higher horizontal resolution allows for more small-scale kinetic energy to be resolved and leads to a broader probability distribution of low-level vertical velocity. This process results in heavier rainfall and convective precipitation extremes in the tropics.
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Received: 26 March 2013
Revised: 19 April 2013
Accepted: 02 May 2013
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Corresponding Author:
BAO Qing
E-mail: baoqing@mail.iap.ac.cn
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