An improved diagnostic stratocumulus scheme based on estimated inversion strength and its performance in GAMIL2  

作　　者：GUO Zhun ZHOU TianJun 

机构地区：[1]Climate Change Research Center (CCRC) [2]State Key Laboratory of Numerical Modeling for Atmospheric Sciences & Geophysical Fluid Dynamics (LASG)

出　　处：《Science China Earth Sciences》2014年第11期2637-2649,共13页中国科学（地球科学英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant No.41125017);the National Basic Research Program of China(Grant No.2010CB951904)

摘　　要：Based on satellite data and the estimated inversion strength(EIS) derived by Wood et al.(2006), a feasible and uncomplicated stratocumulus scheme is proposed, referred to as EIS scheme. It improves simulation of cloud radiative forcing(CRF) in the Grid-point Atmospheric Model of IAP/LASG version 2(GAMIL2.0) model. When compared with the original lower troposphere stability(LTS) scheme, the EIS scheme reproduces more reasonable climatology distributions of clouds and CRF. The parameterization partly corrects CRF underestimation at mid and high latitudes and overestimation in the convective region. Such improvements are achieved by neglecting the effect of free-tropospheric stratification changes that follow a cooler moist adiabat at middle and high latitude, thereby improving simulated cloudiness. The EIS scheme also improves simulation of the CRF interannual variability. The positive net CRF and negative stratiform anomaly in the East Asian and western North Pacific monsoon regions(EAWNPMR) are well simulated. The EIS scheme is more sensitive to sea surface temperature anomalies(SSTA) than the LTS. Therefore, under the effect of a warmer SSTA in the EAWNPMR, the EIS generates a stronger negative stratiform response, which reduces radiative heating in the low and mid troposphere, in turn producing strong subsidence and negative anomalies of both moisture and cloudiness. Consequent decreases in cloud reflection and shading effects ultimately improve simulation of incoming surface shortwave radiative fluxes and CRF. Because of the stronger subsidence, a stronger anomalous anticyclone over the Philippines Sea is simulated by the EIS run, which leads to a better positive precipitation anomaly in eastern China during ENSO winter.Based on satellite data and the estimated inversion strength （EIS） derived by Wood et al. （2006）, a feasible and uncomplicated stratocumulus scheme is proposed, referred to as EIS scheme. It improves simulation of cloud radiative forcing （CRF） in the Grid-point Atmospheric Model of IAP/LASG version 2 （GAMIL2.0） model. When compared with the original lower troposphere stability （LTS） scheme, the EIS scheme reproduces more reasonable climatology distributions of clouds and CRF. The parameterization partly corrects CRF underestimation at mid and high latitudes and overestimation in the convective region. Such improvements are achieved by neglecting the effect of free-tropospheric stratification changes that follow a cooler moist adiabat at middle and high latitude, thereby improving simulated cloudiness. The EIS scheme also improves simulation of the CRF interannual variability. The positive net CRF and negative stratiform anomaly in the East Asian and western North Pacific monsoon regions （EAWNPMR） are well simulated. The EIS scheme is more sensitive to sea surface temperature anomalies （SSTA） than the LTS. Therefore, under the effect of a warmer SSTA in the EAWNPMR, the EIS generates a stronger negative stratiform response, which reduces radiative heating in the low and mid troposphere, in turn producing strong subsidence and negative anomalies of both moisture and cloudiness. Consequent decreases in cloud reflection and shading effects ultimately improve simulation of incoming surface shortwave radiative fluxes and CRF. Because of the stronger subsidence, a stronger anomalous anticyclone over the Philippines Sea is simulated by the EIS run, which leads to a better positive precipitation anomaly in eastern China during ENSO winter.

关 键 词：stratocumulus scheme AGCM cloud radiative forcing 

分 类 号：P426.4[天文地球—大气科学及气象学]