IAP AGCM对全球海温异常的响应——CO_2引起气候变化的等效研究  

Responses of IAP AGCM to Global SST Anomalies —— An Equivalent Study of CO_-induced Climate Changes

作　　者：王万秋[1] 张学洪[1] 曾庆存[1] 

机构地区：[1]中国科学院大气物理研究所,北京100080

出　　处：《大气科学》1993年第2期129-136,共8页Chinese Journal of Atmospheric Sciences

基　　金：国家自然科学基金

摘　　要：本文用IAP AGCM研究全球海温异常引起的气候变化,这种变化可以看作是由于CO_2含量改变引起的响应。按照Ramanathan和Cess等的观点,太阳常数的改变、CO_2含量的增减及全球海温异常对地气系统能量收支的影响是一致的,主要受控于射出净辐射的改变.本工作分别以+4℃和-4℃作为全球海温异常得到两次积分,分别记为I和D,模式的长期气候平均用作基本状态试验,记为C. 当海温增加4℃时,地表气温约增加4.4℃,而且主要由于热带对流加热的影响,气温的变化随高度增加,冬半球地表气温的增加明显大于夏半球,这是由雪的反照率和垂直温度递减率的反馈作用引起的。虽然全球平均总云量随海温增加而减少,但其纬向分布是不均匀的,尤其对个别类型的云更是如此。云的反馈在辐射能量收支中起着重要作用,例如,热带模式层顶净向下太阳辐射(S)和净向上长波辐射(R)减少(或增加最少)就归咎于穿透性对流云的增加. 全球平均降水I比C多18％.降水的变化呈正反馈趋势,即热带降水最大的地区降水加大,而在副热带地区降水增加很小,甚至减少.纬度-时间图上,降水的变化呈带状分布,正象降水本身的变化一样. 虽然我们得到的全球平均和纬向平均与Mitchell的结果一致,但区域性海温异常响应存在很大差别.The two-layer atmospheric general circulation model of the Institute of Atmospheric Physics ( IAP AGCM) is used to study climate changes caused by global sea surface temperature (SST) anomalies. As indicated by Ramanathan (1981), changes in the solar constant , in the carbon dioxide concentration and in sea surface temperatures have the same effects to the atmospheric energy budgets . The control integration (referred as to C) is obtained by prescribing SSTs according to the observed climatology . In this work , two anomalous integrations with SSTs respectively increased and decreased by 4 癈 are carried out and referred as I an D.Increases of the surface air temperatures in the winter hemisphere are larger than those in summer hemisphere due to the snow-albedo and lapse-rate feedbacks and the minimum exists in the polar region of the summer hemisphere .Although the global mean total cloud amount is reduced in the higher-SST integration , the amount of cloud type 1 (CL,) formed by middle-level or penetrative convection is increased with increases of SSTs , especially in the tropics . CL, makes radiative components compensate each other by reducing the absorption of the solar radiation and emission of the infrared radiation of the earth-atmosphere system .Global mean precipitation increases by 18% when the SSTs increase by 4 ℃ . Large scale converging is attributed to the changes of precipitation . The time-latitude section of zonal mean changes in precipitation shows a band structure like the variation of the precipitation itself.Although the global and zonal means in our experiment are similar to those in the experiment of Mitchell et al., the regional distributions are very different from each other .

关 键 词：大气环流 海温 二氧化碳 气候变化 

分 类 号：P467[天文地球—大气科学及气象学]