积云对流和云物理过程调整对气候模拟的影响

本文利用中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室 (LASG/IAP) 的大气环流谱模式SAMIL, 结合观测与政府间气候变化专门委员会第四次评估报告 (IPCC AR4) 大气模式集合平均结果, 以大气辐射通量为例, 诊断分析了物理过程调整前后模式对气候模拟的影响。旧版本SAMIL对大气辐射通量的模拟存在较大偏差, 经过大气辐射过程、 积云对流和诊断云等物理过程的调整后, 新版本SAMIL模拟的全球辐射通量的年平均结果与观测的偏差大幅减小, 其中大气顶能量收支的年变化及其平均值与观测更为接近。在积云对流方案调整基础上, 通过对诊断云物理方案的进一步调整, 新版本SAMIL对云物理量模拟更为合理, 在赤道辐合带等区域, 在很大程度上克服了单一积云对流物理过程调整引起的云宏观和微观属性不匹配问题, 能模拟出夏季气候平均辐射通量的全球分布特征, 尤其在东亚区域有较好的模拟能力。研究还表明, 在热带和副热带对流活跃区域, 当前SAMIL中积云对流过程偏差对辐射通量的模拟偏差有很大影响, 而模式中较为简单的诊断云方案也会将云宏观物理量模拟偏差带入云微观量模拟中, 也是主要偏差源之一。本文结果表明, 要继续提高SAMIL的模拟性能, 急需更新云物理参数化方案以改进云辐射过程的模拟, 同时也需要有针对性的研究积云对流和云物理过程之间相互作用, 并作进一步协同调整。     

热带大气对流垂直结构与降水模拟偏差的关系：基于GAMIL3模式的分析

针对LASG/IAP发展的大气环流模式GAMIL(Grid-point Atmospheric Model of IAP LASG)的两个版本GAMIL2(G2)和GAMIL3(G3)，评估了其对热带降水气候态以及对流垂直结构的模拟能力，在此基础上探究了新版本模式降水模拟改进的原因以及热带对流垂直结构与降水模拟偏差的关系。两个版本的GAMIL模式都较好地捕捉到了热带降水的主要特征，且G3的模拟结果整体优于G2。新版本的主要改进在于显著减小了热带西北太平洋正降水偏差。水汽收支诊断显示，模式降水偏差主要来源于蒸发项和水汽垂直平流动力项，而后者的偏差则来自于对流强度和对流垂直结构的共同作用。对流垂直结构偏差主要存在于赤道印度洋与赤道大西洋区域，表现为大气低层辐合分量偏小，对流卷出层高度偏高；在热带西北太平洋与赤道东太平洋区域，模式较好地还原了典型的“头重型”和“脚重型”对流垂直结构，但依然存在有整体性的对流偏深。湿静力能（MSE）收支显示，热带西北太平洋区域过量的净能量通量是模式垂直运动偏差的主要来源。而对流垂直结构偏深造成的总湿稳定度（Gross Moist Stability，简称GMS...     

积云对流参数化方案对大气含水量及降水的影响

中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室所发展的高分辨率全球大气环流谱模式SAMIL, 自从发展成R42L26新版本之后, 显示出对全球气候基本态的模拟能力, 但模式对流层低层以及热带地区整层偏干, 且对热带地区的降水模拟存在“双赤道辐合带”这一普遍误差, 在赤道地区以及北半球中纬度降水偏少, 而在拉丁美洲降水偏多。敏感性试验表明这些误差是相互联系的。通过将700 hPa以下的相对湿度趋近于“观测资料”的试验显示模拟的降水误差减小了。据此, 对Tiedtke 积云对流参数化方案中的浅对流部分进行修改, 增加了浅对流的侧向混合的卷入以及卷出率, 并减小了对流方案中的云水[CD*2]雨水的转换率, 将其耦合到模式中。积分结果表明, 修改后的方案明显改进了湿度和温度场的模拟, 对降水的模拟能力有了很大的提高, 基本消除了“双赤道辐合带”现象。     

分辨率对区域气候极端事件模拟的影响

利用NCAR MM5V3对1999年6月长江流域的极端异常降水事件进行了模拟,主要研究不同水平和垂直分辨率对极端区域气候事件模拟的影响。数值模拟试验表明:模式能够模拟出极端强降水的主要分布特征;水平分辨率的提高降低了模式模拟的强降水偏差,对逐日降水变化的模拟更加合理,而垂直分辨率的提高基本上也都减小了模拟的强降水过程的偏差,改善对强降水的模拟能力;模式水平、垂直分辨率的提高在一定程度上增强了对强降水过程的模拟能力。水平分辨率的提高能够改善模式对海平面气压的模拟,而垂直分辨率的提高可以改善模式模拟的地面气温和低层环流。分辨率对中层大气环流的影响不是很敏感。不同积云对流参数化方案模拟的对流降水比率随水平分辨率的变化是不同的,Grell方案对流降水比例随分辨率的提高而增加,而Kain-Fritsch方案的结果相反。     

热带低频振荡影响中国东部冬季降水的机理

利用1979—2007年中国站点逐日降水记录、NCEP/NCAR大气再分析资料以及OLR资料等,分析了冬季热带低频振荡(MJO)与中国东部降水的关系及其伴随的大气环流扰动型,利用线性化全球大气环流模式模拟了大气对热带对流热源的响应,揭示了MJO影响中国东部冬季降水的机理。结果表明:热带对流活动从赤道印度洋西部东移至赤道西太平洋,中国东部冬季降水先后经历了长江流域多雨、整个南方多雨、华南多雨而长江流域少雨,这个过程大约经历了20 d左右时间。作为对东移性赤道热源的Rossby波型响应,当对流热源中心位于赤道印度洋中西部时,赤道以北地区的热源西部气旋式环流和热源东部反气旋式环流共同形成的西南气流扰动主要影响到中国长江流域,并造成那里多雨;而当对流热源中心东移到赤道印度洋东部时,西南气流扰动主要影响到中国华南地区,并造成那里多雨。     

积云对流参数化方案对气候数值模拟的影响

利用一个“全球五层大气环流谱模式”,试验和比较了三种不同积云对流参数化方案,即Manabe方案、Kuo方案和Arakawa-Schubert（A-S）方案,对全球气候数值模拟的影响。数值模拟的结果表明了三种方案对全球降水的模拟差别较大,差别比较明显的区域是东亚、北美和北非,且夏季的差别比冬季大。与实况相比,采用Kuo方案对东亚季风降水的模拟结果较好,而采用A-S方案对热带西太平洋、热带印度洋与北美地区降水的模拟结果较好,但采用Manabe方案却模拟不出东亚地区夏季风降水特征;并且从环流数值模拟的结果看,采用这三种方案均模拟出北半球冬、夏季中、高纬地区的环流结构,但与实况相比,采用Kuo方案能较好地模拟出冬季极涡分裂过程,并能较好地模拟出中高纬地区和东亚地区的环流系统,而采用A-S方案能较好地模拟出冬、夏季北美环流系统和太平洋副热带高压;此外,这三种方案对加热场与水汽场的描述方面也有很大不同,A-S方案的结果呈现出不同于Kuo和Manabe方案结果的特征,表明了A-S方案能反映强对流特征,而Kuo方案和 Manabe方案所描述的加热场和水汽场虽有相似之处,但在30#+[o]N以南的副热带地区,Kuo方案所描述的对流系统加热要比Manabe方案强。     

气候系统模式FGOALS-s1.1对热带降水年循环模态的模拟

文中评估了中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室(LASG/IAP)新一代耦合气候模式Fgoals_s1.1对热带降水年循环模态的模拟能力。通过与观测表层海温(SST)强迫的大气模式SAMIL试验结果比较,分析了海气耦合过程对年循环模态模拟效果的影响。结果表明Fgoals_s1.1能合理再现热带地区降水年循环模态的基本特征。Fgoals_s1.1模拟出了年平均降水场中的主要降水中心,但模拟的赤道和南太平洋降水偏多,而北太平洋降水则偏少。Fgoals_s1.1的季风模态降水呈现与观测一致的关于赤道反对称的特征,其模拟偏差大部分来自大气分量,尤其是在赤道外。Fgoals_s1.1的主要缺陷在于它对春秋非对称模态模拟能力低于单独大气模式,这主要是由于耦合模式模拟的SST距平的年循环位相与观测相反。SST纬向梯度的位相偏差使得太平洋沃克环流和印度洋的反沃克环流在春季强于秋季,最终导致模拟的春秋非对称模态的偏差。Fgoals_s1.1模拟的季风区范围接近观测,存在的问题在于模拟的西北太平洋季风区、东亚季风区都偏小。本文结果表明,大气模式偏差仅是Fgoals_s1.1在降水年循环模态模拟上的偏差的部分来源,改进模式模拟的SST,特别是赤道地区SST季节循环,是今后Fgoals_s1.1发展过程中急需解决的问题。     

热带加热异常影响冬季平流层极涡强度的数值模拟

本文利用大气环流模式SAMIL/LASG,通过选择两种对流参数化方案,研究了热带加热异常对热带外平流层模拟的影响。结果表明,因不同对流参数化方案引起的热带对流加热状况的差异,可显著影响模式对北半球冬季平流层极涡强度的模拟偏差。与采用Manabe对流参数化方案相比,采用Tiedtke参数化方案可以显著改善对平流层极涡强度的模拟,使平流层极涡“过强”及极区“过冷”的模拟偏差得到明显改善。研究其中的影响过程发现,由于Manabe方案最大凝结潜热加热高度过低,在对流层中低层;而Tiedtke方案的最大凝结潜热加热位置在对流层中上层,因而Tiedtke(Manabe)方案时热带大气温度在对流层中上层较为偏暖(偏冷),在平流层低层较为偏冷(偏暖)。自秋季开始,与热带对流层高层温度的暖偏差相联系,热带外对流层高层以及热带平流层低层出现伴随的温度冷偏差;与之对应,平流层中纬度从秋季开始也出现持续的温度暖偏差。另外,随着秋冬季节平流层行星波活动的出现,Tiedtke方案时热带外地区行星波1波的强度也明显强于Manabe方案,使得秋冬季节涡动引起的向极热通量在Tiedtke方案时明显偏强,从而造成了冬季平流层极区温度偏暖、极涡强度偏弱。     

BCC_CSM模式对热带降水年循环模态的模拟

本文评估了国家气候中心发展的两个不同分辨率海—陆—气—冰多圈层耦合气候系统模式BCC_CSM1.1和BCC_CSM1.1 (m) 对热带降水两个年循环模态——揭示降水冬夏季节差异的季风模态和揭示过渡季节春季和秋季非对称特征的春秋非对称模态的模拟能力,讨论了模拟偏差产生的可能原因。分析结果表明,BCC_CSM1.1和BCC_CSM1.1 (m) 均能合理再现全球年平均降水的基本分布特征,也能较合理再现热带降水年循环模态的基本分布特征,尤其季风模态中降水与环流关于赤道反对称的特征;能够较合理再现春秋非对称模态与热带海洋表面温度(SST)年循环之间的关系。大气温度场、环流场以及热带SST的模拟偏差对降水季风模态有影响;热带SST年循环的偏差对降水春秋非对称模态的模拟偏差有贡献;模式分辨率对降水年循环模态的模拟也有一定影响。对比分析显示,大气模式和陆面模式水平分辨率提高之后模式在某些模拟性能上有所提高,这表现在:BCC_CSM1.1 (m) 模拟的1～12月降水气候态的空间变率更接近观测;热带海表温度年循环总体上更接近观测;模拟的热带降水年循环模态的部分特征更合理。但BCC_CSM1.1 (m) 的模拟结果相对观测仍存在较大偏差,有待进一步改进。     

积云参数化方案对热带降水年循环模态模拟的影响

本文利用中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室( LASG)发展的大气环流模式(SAMIL),采用Zhang-McFarlane (ZM)和Tiedtke (TDK)两种积云对流参数化方案,讨论了积云对流参数化方案对热带降水年循环模态模拟的影响.结果表明,两种积云对流参数化方案均能合理再现...     

大气环流模式和耦合模式模拟的降水-海温关系之比较

本文讨论了气候系统耦合模式FGOALS_s模拟的局地降水和海温的关系, 并通过与单独大气模式SAMIL的AMIP试验结果进行对比分析, 考察了海气耦合过程对局地降水和海温关系模拟的影响。结果表明, 耦合模式FGOALS_s和单独大气模式SAMIL在模拟局地降水和海温关系上各有优势。在赤道中东太平洋地区, 观测中局地降水和海温的关系是海洋强迫为主, FGOALS_s模拟的海洋对大气的强迫比观测偏弱, 因此, SAMIL相对于FGOALS_s更有优势。在西北太平洋东部地区, 观测中夏秋季节降水和海温的关系是大气强迫为主, 由于考虑了海气相互作用过程, FGOALS_s对降水和海温关系的模拟能力要优于单独的大气模式。此外, 由于大气模式SAMIL的云参数化方案导致的模拟偏差, 在赤道中东太平洋地区 (9～11月), 降水增加时入射的短波辐射通量也是增加的, 并且这种模拟的偏差在耦合后仍然保留了下来, 导致了与观测不符的云[CD*2]辐射反馈过程。因此, 改进大气模式的云参数化方案是未来工作重点之一。此外, 分析发现耦合模式模拟的潜热通量的变化过分依赖海气湿度差。     

Comparison Between GAMIL, and CAM2 on Interannual Variability Simulation

Recently, a new atmospheric general circulation model （GAMIL： Grid-point Atmospheric Model of IAP LASG） has been developed at the Institute of Atmospheric Physics （IAP）, Chinese Academy of Sciences （CAS）, which is based on the Community Atmospheric Model Version 2 （CAM2） of the National Center for Atmospheric Research （NCAR）. Since the two models have the same physical processes but different dynamical cores, the interannual variability simulation performances of the two models are compared. The ensemble approach is used to reduce model internal variability. In general, the simulation performances of the two models are similar. Both models have good per- formance in simulating total space-time variability and the Southern Oscillation Index. GAMIL performs better in the Eastern Asian winter circulation simulation than CAM2, and the model internal variability of GAMIL has a better response to external forcing than that of CAM2. These indicate that the improvement of the dynamic core is very important. It is also verified that there is less predictability in the middle and high latitudes than in the low latitudes.     

The Baseline Evaluation of LASG/IAP Climate System Ocean Model (LICOM) Version 2

The baseline performance of the latest version (version 2) of an intermediate resolution, stand-alone climate oceanic general circulation model, called LASG/IAP (State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics/Institute of Atmospheric Physics) Climate system Ocean Model (LICOM), has been evaluated against the observation by using the main metrics from Griffies et al. in 2009. In general, the errors of LICOM2 in the water properties and in the circulation are comparable with the models of Coordinated Ocean-ice Reference Experiments (COREs). Some common biases are still evident in the present version, such as the cold bias in the eastern Pacific cold tongue, the warm biases off the east coast of the basins, the weak poleward heat transport in the Atlantic, and the relatively large biases in the Arctic Ocean. A unique systematic bias occurs in LICOM2 over the Southern Ocean, compared with CORE models. It seems that this bias may be related to the sea ice process around the Antarctic continent.     

区域海气耦合模式FROALS的发展及其应用

区域海气耦合模式是研究局地海气相互作用过程影响气候变率的重要平台,也是对全球气候模式进行"动力降尺度"的重要工具.本文介绍了LASG(State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics)/IAP(Institute of Atmospheric Physics)发展的区域海气耦合模式FROALS(Flexible Regional Ocean-Atmosphere-Land System model),并总结了过去五年围绕该区域海气耦合模式开展的研究工 作.FROALS的特点之一是有两个完全不同的大气模式分量和海洋模式分量选项,可以适应不同的模拟研究需 求.针对区域海气耦合模式在西北太平洋地区的模拟偏差,通过分步骤考察不同大气模式分量和不同海洋模式分量对模式模拟性能的影响,指出大气模式是导致区域海气耦合偏差的主要分量.通过改进对流触发的相对湿度阈值标准,有效地改善了此前区域海气耦合模式在亚洲季风区普遍出现的"模拟海温冷偏差".改进的FROALS对西北太平洋地区的大气和海洋环境有较好的模拟能力,合理地再现了西北太平洋地区表层洋流气候态和年际变率.较之非耦合模式,考虑区域海气耦合过程后,改进了东亚和南亚地区的降水和热带气旋潜势年际变率的模拟.最后,针对东亚—西北太平洋地区,利用FROALS对IAP/LASG全球气候模式模拟和预估的结果进行了动力降尺 度,得到了东亚区域50 km高分辨率区域气候变化信息.分析显示,FROALS模拟得到的东亚区域气候较之全球气候模式和非耦合区域气候模式结果具有明显的"增值",显示出区域海气耦合模式在该区域良好的应用前景.     

Simulation of Asian Monsoon Seasonal Variations with Climate Model R42L9／LASG

The seasonal variations of the Asian monsoon were explored by applying the atmospheric general circulation model R42L9 that was developed recently at the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences (LASG/IAP/CAS). The 20-yr (1979-1998) simulation was done using the prescribed 20-yr monthly SST and sea-ice data as required by Atmospheric Model Intercomparison Project (AMIP)Ⅱ in the model. The monthly precipitation and monsoon circulations were analyzed and compared with the observations to validate the model‘s performance in simulating the climatological mean and seasonal variations of the Asian monsoon. The results show that the model can capture the main features of the spatial distribution and the temporal evolution of precipitation in the Indian and East Asian monsoon areas. The model also reproduced the basic patterns of monsoon circulation. However, some biases exis tin this model. The simulation of the heating over the Tibetan Plateau in summer was too strong. The overestimated heating caused a stronger East Asian monsoon and a weaker Indian monsoon than the observations. In the circulation fields, the South Asia high was stronger and located over the Tibetan Plateau. The western Pacific subtropical high was extended westward, which is in accordance with the observational results when the heating over the Tibetan Plateau is stronger. Consequently, the simulated rainfall around this area and in northwest China was heavier than in observations, but in the Indian monsoon area and west Pacific the rainfall was somewhat deficient.     

A fast version of LASG/IAP climate system model and its 1000-year control integration

A fast version of the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geo- physical Fluid Dynamics(LASG)/Institute of Atmospheric Physics(IAP)climate system model is briefly documented.The fast coupled model employs a low resolution version of the atmospheric component Grid Atmospheric Model of IAP/LASG(GAMIL),with the other parts of the model,namely an oceanic component LASG/IAP Climate Ocean Model(LICOM),land component Common Land Model(CLM),and sea ice component from National Center for Atmospheric Research Community Climate System Model (NCAR CCSM2),as the same as in the standard version of LASG/IAP Flexible Global Ocean Atmosphere Land System model(FGOALS g).The parameterizations of physical and dynamical processes of the at- mospheric component in the fast version are identical to the standard version,although some parameter values are different.However,by virtue of reduced horizontal resolution and increased time-step of the most time-consuming atmospheric component,it runs faster by a factor of 3 and can serve as a useful tool for long- term and large-ensemble integrations.A 1000-year control simulation of the present-day climate has been completed without flux adjustments.The final 600 years of this simulation has virtually no trends in global mean sea surface temperatures and is recommended for internal variability studies.Several aspects of the control simulation’s mean climate and variability are evaluated against the observational or reanalysis data. The strengths and weaknesses of the control simulation are evaluated.The mean atmospheric circulation is well simulated,except in high latitudes.The Asian-Australian monsoonal meridional cell shows realistic features,however,an artificial rainfall center is located to the eastern periphery of the Tibetan Plateau persists throughout the year.The mean bias of SST resembles that of the standard version,appearing as a"double ITCZ"(Inter-Tropical Convergence Zone)associated with a westward extension of the equatorial eastern Pacific cold tongue.The sea ice extent is acceptable but has a higher concentration.The strength of Atlantic meridional overturning is 27.5 Sv.Evidence from the 600-year simulation suggests a modulation of internal variability on ENSO frequency,since both regular and irregular oscillations of ENSO are found during the different time periods of the long-term simulation.     

A study of biases in simulation of the Indian Ocean basin mode and its capacitor effect in CMIP3/CMIP5 models

Based on 15 Coupled Model Intercomparison Project (CMIP) phase 3 (CMIP3) and 32 CMIP phase 5 (CMIP5) models, a detailed diagnosis was carried out to understand what compose the biases in simulation of the Indian Ocean basin mode (IOBM) and its capacitor effect. Cloud-radiation-SST (CRS) feedback and wind-evaporation-SST (WES) feedback are the two major atmospheric processes for SST changes. Most CMIP models simulate a stronger CRS feedback and a weaker WES feedback. During boreal fall of the El Niño/Southern Oscillation developing year and the following spring, there are weak biases of suppressed rainfall anomalies over the Maritime Continent and anomalous anticyclone over South Indian Ocean. Most CMIP models simulate reasonable short wave radiation (SWR) and weaker latent heat flux (LHF) anomalies. This leads to a weak bias of atmospheric processes. During winter, however, the rainfall anomalies are stronger due to west bias, and the anomalous anticyclone is comparable to observations. As such, most models simulate stronger SWR and reasonable LHF anomalies, leading to a strong bias of atmospheric processes. The thermocline feedback is stronger in most models. Though there is a deep bias of climatology thermocline, most models capture reasonable sea surface height-induced SST anomalies. Therefore, the effect of oceanic processes offset the weak bias of atmospheric processes in spring, and the tropical Indian Ocean warming persists into summer. However, anomalous northwest Pacific (NWP) anticyclone is weaker due to weak and west bias of the capacitor effect. The unrealistic western Pacific SST anomalies in models favor the westward extension of Rossby wave from the Pacific, weakening the effect of Kelvin wave from the Indian Ocean. Moreover, the western Pacific warming forces the NWP anticyclone move farther north than observations, suggesting a major forcing from the Pacific. Compared to CMIP3, CMIP5 models simulate the feedbacks more realistically and display less diversity. Thus, the overall performance of CMIP5 models is better than that of CMIP3 models.     

Evaluation of Surface Air Temperature Change over China and the Globe during the Twentieth Century in IAP AGCM4.0

Based on time series and linear trend analysis, the authors evaluated the performance of the fourth generation atmospheric general circulation model developed at the Institute of Atmospheric Physics, Chinese Academy of Sciences (IAP AGCM4.0), in simulating surface air temperature (SAT) during the twentieth century over China and the globe. The numerical experiment is conducted by driving the model with the observed sea surface temperature and sea ice. It is shown that IAP AGCM4.0 can simulate the warming trend of the global SAT, with the major warming regions in the high latitudes of the Northern Hemisphere and the mid-latitudes of the Southern Hemisphere. While the simulated trend over the whole globe is close to the observation, the model under-estimates the observed trend over the continents. More-over, the model simulates the spatial distribution of SAT in China, with a bias of approximately-2°C in eastern China, but with a more serious bias in western China. Compared with the global mean, however, the correlation coefficient between the simulation and observation in China is significantly lower, indicating that there is large uncertainty in simulating regional climate change.     

Boreal winter rainfall anomaly over the tropical indo-pacific and its effect on northern hemisphere atmospheric circulation in CMIP5 models

Experimental outputs of 11 Atmospheric Model Intercomparison Project （AMIP） models from phase 5 of the Coupled Model Intercomparison Project （CMIP5） are analyzed to assess the atmospheric circulation anomaly over Northern Hemisphere induced by the anomalous rainfall over tropical Pacific and Indian Ocean during boreal winter.The analysis shows that the main features of the interannual variation of tropical rainfall anomalies,especially over the Central Pacific （CP） （5°S-5°N,175°E-135°W） and Indo-western Pacific （IWP） （20°S-20°N,110°-150°E） are well captured in all the CMIP5/AMIP models.For the IWP and western Indian Ocean （WIO） （10°S-10°N,45°-75°E）,the anomalous rainfall is weaker in the 11 CMIP5/AMIP models than in the observation.During El Ni（n）o/La Ni（n）a mature phases in boreal winter,consistent with observations,there are geopotential height anomalies known as the Pacific North American （PNA） pattern and Indo-western Pacific and East Asia （IWPEA） pattern in the upper troposphere,and the northwestern Pacific anticyclone （cyclone） （NWPA） in the lower troposphere in the models.Comparison between the models and observations shows that the ability to simulate the PNA and NWPA pattern depends on the ability to simulate the anomalous rainfall over the CP,while the ability to simulate the IWPEA pattern is related to the ability to simulate the rainfall anomaly in the IWP and WIO,as the SST anomaly is same in AMIP experiments.It is found that the tropical rainfall anomaly is important in modeling the impact of the tropical Indo-Pacific Ocean on the extratropical atmospheric circulation anomaly.