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自由表面海洋环流模式的正、斜压模分解算法 总被引：1，自引：0，他引：1
大气物理研究所海洋环流模式（IAP OGCM）特点之一是消除“刚盖”近似，引入海面起伏作为模式的预报变量。为此，需设计有效的时间积分方案，以克服模式中所保留的表面重力波对时间步长的苛刻限制。本文给出了适应过程中流场正压和斜压模分解算法。研究表明，把海洋模式适应过程进一步分解为与海面起伏相联系的正压模和与密度不均匀分布相联系的斜压模，用不同的时间步长数值求解，计算效率可提高数倍以上。文中用四层IAP OGCM在北太平洋区域定量地比较了节省计算时间的有效性，并给出数值计算实例。 相似文献
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用本文第Ⅰ部分所给出的四层太平洋环流模式,模拟在定常年平均大气强迫场驱动下太平洋长期平均环流。所进行的53年数值积分表明,模式成功地模拟出观测到的太平洋大尺度环流基本特征,特别是能直接计算出在海洋动力学和大尺度海气相互作用研究中有重要应用的海面起伏,对表层流场的模拟也明显优于具有同等分辨率的其他模式的结果;对气候有重要影响的SST形势的模拟结果同观测也较为一致。本文还用第53年数值积分资料进行了扰动压力场、斜压扰动压力场和海表热通量等的诊断计算和分析。文中还对模拟结果进行了物理和动力学的分析和解释。 相似文献
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本工作发展了一个用于研究热带海洋-大气系统相互作用和El Ni?o/Southern Oscillation动力过程的混合型(hybrid)耦合模式，其中的大气部分为一个由一阶斜压模表示的自由大气和混合行星边界层所组成的简单热带大气模式(区域为热带太平洋:120°E～80°W，30°N～30°S；水平分辨率为2°×2°)，海洋部分为大气物理研究所高分辨率自由表面热带太平洋环流模式(经纬圈方向水平分辨率分别为1°和2°，垂直方向分为不等距的14层)。两模式间的耦合是这样进行的:简单大气模式计算出海表风应力，热通量由松弛公式计算，淡水通量(蒸发与降水之差)由观测资料给定，它们一起作为海洋环流模式(OGCM)的强迫场；而OGCM计算出海表温度(SST)，在其以外地区给定观测到的气候海表温度或陆地温度，作为大气模式的边界条件。本文给出采用逐日、同步耦合方案时模式对热带太平洋气候态模拟结果，表明未采用任何通量修正(fluxes correction)，耦合模式未出现气候漂移(climate drift)现象，并且非常逼真地再现了热带太平洋气候态，特别是海表风场及相伴随的辐合带和降水、海表温度和流场及它们的季节变化。文中还进行了对耦合模式的比较研究，以验证其良好性能和对实际热带太平洋气候系统的模拟能力。 相似文献
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热带太平洋环流季节变化的数值模拟 总被引：3，自引：0，他引：3
在观测到的海表风应力和热量及淡水通量驱动下，用大气物理研究所发展的高分辨率自由表面热带太平洋环流模式对热带太平洋环流季节变化进行了数值模拟。对模拟得到的热带太平洋海面起伏、温度场和流场等季节变化分析、比较表明，模式成功地模拟了观测到的环流季节变化基本特征。其中，海面起伏中西北太平洋副热带反气旋环流在冬季最强，赤道槽在冬季和早春季强，而赤道脊和北赤道逆流槽则在秋季强；北赤道逆流在秋季强而春季弱，150°W附近区域赤道表层洋流流向在4至7月逆转；赤道东太平洋地区海表温度场春季增暖和秋冷却；以及次表层赤道斜温层 相似文献
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利用NCAR CCM2十八层全球大气环流谱模式和IAP／LASG OGCM二十层全球大洋环流模式，设计了一个通量场再分析同步耦合方案FRAC（Flux Re—Analysis Coupling scheme），建立了全球海气耦合模式系统（NIM／COAMS）。利用EOF理论消除分量模式通量在海气非线性相互作用过程中产生的高频振荡，保留模式通量场的主要成分．使模式误差不致被迅速放大。模拟结果表明，积分前10a全球平均海表温度仅上升0．1℃，全球平均表面温度仅上升0．3℃，以后基本保持不变，模式没有出现明显的气候漂移，50a积分显示，模式对气候态的模拟与观测基本一致，部分结果优于未耦合模式。 相似文献
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利用全球海洋—大气快速耦合模式（Fast Ocean-Atmosphere Model,FOAM）,采用模式中的初值方法,研究了湾流区海温再现过程及其对北半球大气环流和气候的影响。FOAM模式很好地模拟了北大西洋湾流区的海温＂再现＂过程,模式中海面热通量异常与SST异常表现出不同步的响应特征。海面热通量异常在初冬季节达到最大值,而SST异常滞后,在冬季晚期达到最大值,从而在初冬和晚冬对北半球大气环流造成不同的影响。初冬季节北半球大气环流主要受海洋热通量异常的强迫,在北大西洋和北太平洋上空呈现相当正压的异常低压槽响应,北极地区为异常高压脊,类似北极涛动的负位相,可能造成欧洲南部和北非大陆气温偏高,亚洲大陆气温偏低。而晚冬季节北半球大气环流主要受SST异常的驱动,在北大西洋和北太平洋上空表现为相当正压的异常高压脊响应,北极地区为异常低压槽,类似北极涛动的正位相,可能造成欧洲南部和北非大陆气温偏低,亚洲大陆气温偏高,中国东部降水异常偏多30%左右。北太平洋大气环流的异常由北大西洋湾流区海洋热通量和SST异常强迫下游大气环流所激发,进一步通过Rossby驻波的能量频散东传至北太平洋而造成的。 相似文献
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本文是用简单海一气耦合模型模拟温盐环流在全球增暖事件中作用的研究工作的第一部分。为了建立一个简单海一气耦合模型，我们首先根据Ｗｒｉｇｈｔ和Ｓｔｏｋｅｒ等人的设计复制出一个包括大西洋、太平洋和南大洋在内的二维温盐环流模式，从等温、等盐和无运动的初始状态出发，在给定的年平均海表强迫下将模式积分了４０００年，模拟出了和原作相似的温盐环流。对模拟结果的分析表明，相对于北太平洋而言，北大西洋北部的高盐、低温特点（后者是由两大洋在地理上的差别决定的）是形成当代温盐环流的主要原因；从与温盐环流相联系的海表热通量来看，北大西洋北部是向大气提供热量的主要源地；模式温盐环流对于海表盐度通量的敏感性试验的结果表明，对于纬圈平均的二维模式而言，要想模拟出合理的温盐环流就必须人为地提高北大西洋北部的海表盐度，文章分析了这种作法的物理根据；模式中的对流过程对于温盐环流的维持是至关重要的，对比有无季节循环的试验结果可以看出，虽然温度场的明显的季节变化只出现在模式的最上面两层，但由于引进季节循环后冬季高纬海洋的对流活动加强，后者直接影响到温盐环流，使更多的深海热量上传并向大气释放。这是使海洋温跃层得以保持合理．厚度的一个重要原因。 相似文献
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利用NOAA最优插值逐日海表温度(SST)资料和NCEP/NCAR的逐日大气再分析资料,本文分析了黑潮延伸体区域海表温度锋的变化对北太平洋风暴轴的影响。结果表明,黑潮延伸体区域海表温度锋位置的季节变化很弱,而其强度的变化则非常显著,北太平洋风暴轴强度与海表温度锋强度具有一致的协同变化。冬季黑潮延伸体区域海表温度锋强度最强,增强了其上空大气的斜压性,从平均有效位能向涡动有效位能的斜压能量转换以及从涡动有效位能向涡动动能的斜压能量转换均在黑潮延伸体区域显著增加,斜压涡旋在此区域生成更加频繁,在随西风向下游运动过程中不断从背景平均流中获得能量,从而导致北太平洋风暴轴增强,且将其中心轴线固定在黑潮延伸体区域上空,而夏季黑潮延伸体区域海表温度锋强度非常弱,其上空大气斜压性减弱,从平均有效位能向涡动有效位能的斜压能量转换以及从涡动有效位能向涡动动能的斜压能量转换均显著减少,斜压涡旋在此区域生成减少,导致北太平洋风暴轴减弱,且中心移至太平洋中部,位置偏北。 相似文献
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本文基于观测资料和LICOM2.0模拟结果的分析研究,简要介绍讨论了太平洋—印度洋海温(异常)联合模(PIOAM)的存在、特征、演变及其影响等问题。热带太平洋—印度洋区域乃至全球范围的海表温度异常(SSTA)资料进行EOF分解,都清楚表明其第一分量在热带太平洋—印度洋的空间形态与太平洋—印度洋海温(异常)联合模(PIOAM)非常相似,说明PIOAM是热带太平洋—印度洋实实在在存在的一种海温异常模态。对应PIOAM的正、负位相,热带印度洋和西太平洋地区的夏季(JJA)850 hPa距平风场有近乎相反的异常流场形势;对流层低层的Walker环流支和亚洲夏季风都出现了不同特征的(近乎相反)异常;在PIOAM正(负)位相将使得100 hPa的南亚高压位置偏东(西)。对热带太平洋和印度洋温跃层曲面上的海温异常(为了方便将其称为SOTA)进行EOF分解,发现其第一模态也是一个三极子模态,即当赤道中西印度洋大部分海域与赤道中东太平洋大部分海域偏暖(偏冷)时,赤道东印度洋和赤道西太平洋大部分海域则偏冷(偏暖);它与太平洋—印度洋表层的PIOAM十分类似,也表明PIOAM在海洋次表层也是存在的。高分辨海洋环流模式LICOM2.0的模拟结果,无论是对太平洋—印度洋表层还是次表层的PIOAM的特征和演变都刻画得很好,这从另一个角度进一步说明PIOAM是热带太平洋—印度洋实际存在的一种海温变化模态。PIOAM正、负位相不仅对亚洲及西太平洋地区的天气气候有非常不一样的影响(不少地方有反向的特征),还会对南北美洲和非洲一些地区产生不同影响;而且其影响与单独的厄尔尼诺(El Ni?o)及印度洋偶极子(IOD)都不尽相同。 相似文献
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影响南海夏季风爆发年际变化的关键海区及机制初探 总被引：1，自引：7，他引：1
利用1958—2011年NCEP/ NCAR再分析资料和ERSST资料,采用Lanczos时间滤波器、相关分析、回归分析、合成分析和交叉检验等方法,研究了影响南海夏季风爆发年际变化的关键海区海温异常的来源与可能机制。结果表明,前冬(12—2月)热带西南印度洋和热带西北太平洋是影响南海夏季风爆发年际变化的关键海区。冬季热带西南印度洋(热带西北太平洋)的异常增暖是由前一年夏季El Ni?o早爆发(强印度季风异常驱动的行星尺度东-西向环流)触发、热带印度洋(西北太平洋)局地海气正反馈过程引起并维持到春季。冬季热带西北太平洋反气旋性环流(气旋性环流)及印度洋(热带西北太平洋)的暖海区局地海气相互作用使得印度洋(热带西北太平洋)海温异常维持到春末。春季,逐渐加强北移到10 °N附近的低层大气对北印度洋(热带西北太平洋)暖海温异常响应的东风急流(异常西风)及南海-热带西北太平洋维持的反气旋性环流(气旋性环流)异常,使得南海夏季风晚(早)爆发。 相似文献
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Yun YANG Jianping LI Lixin WU Yu KOSAKA Yan DU Cheng SUN Fei XIE Juan FENG 《大气科学进展》2017,34(11):1282-1289
A robust decadal Indian Ocean dipolar variability(DIOD) is identified in observations and found to be related to tropical Pacific decadal variability(TPDV).A Pacific Ocean–global atmosphere(POGA) experiment,with fixed radiative forcing,is conducted to evaluate the DIOD variability and its relationship with the TPDV.In this experiment,the sea surface temperature anomalies are restored to observations over the tropical Pacific,but left as interactive with the atmosphere elsewhere.The TPDV-forced DIOD,represented as the ensemble mean of 10 simulations in POGA,accounts for one third of the total variance.The forced DIOD is triggered by anomalous Walker circulation in response to the TPDV and develops following Bjerknes feedback.Thermocline anomalies do not exhibit a propagating signal,indicating an absence of oceanic planetary wave adjustment in the subtropical Indian Ocean.The DIOD–TPDV correlation differs among the 10 simulations,with a low correlation corresponding to a strong internal DIOD independent of the TPDV.The variance of this internal DIOD depends on the background state in the Indian Ocean,modulated by the thermocline depth off Sumatra/Java. 相似文献
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The role of the Indonesian Throughflow(ITF) in the influence of the Indian Ocean Dipole(IOD) on ENSO is investigated using version 2 of the Parallel Ocean Program(POP2) ocean general circulation model. We demonstrate the results through sensitivity experiments on both positive and negative IOD events from observations and coupled general circulation model simulations. By shutting down the atmospheric bridge while maintaining the tropical oceanic channel, the IOD forcing is shown to influence the ENSO event in the following year, and the role of the ITF is emphasized. During positive IOD events,negative sea surface height anomalies(SSHAs) occur in the eastern Indian Ocean, indicating the existence of upwelling.These upwelling anomalies pass through the Indonesian seas and enter the western tropical Pacific, resulting in cold anomalies there. These cold temperature anomalies further propagate to the eastern equatorial Pacific, and ultimately induce a La Nia-like mode in the following year. In contrast, during negative IOD events, positive SSHAs are established in the eastern Indian Ocean, leading to downwelling anomalies that can also propagate into the subsurface of the western Pacific Ocean and travel further eastward. These downwelling anomalies induce negative ITF transport anomalies, and an El Nio-like mode in the tropical eastern Pacific Ocean that persists into the following year. The effects of negative and positive IOD events on ENSO via the ITF are symmetric. Finally, we also estimate the contribution of IOD forcing in explaining the Pacific variability associated with ENSO via ITF. 相似文献
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热带太平洋与印度洋相互作用的年代际变化及其数值模拟 总被引：2，自引：2，他引：0
利用全球海表温度资料和NCEP／NCAR再分析资料,发现热带印度洋偶极子事件与热带太平洋ENSO事件存在相互作用,但其相互作用关系在1961年前后发生了明显的跃变。通过CCM3（community climate model version3）模式,研究了不同年代热带太平洋和热带印度洋SST（seasur—face temperature）变化对其上空大气环流影响的变化,结果表明：1961年后,热带印度洋发生正偶极子事件时,两大洋的垂直环流异常的耦合很强,热带太平洋上空大气环流对印度洋偶极子事件的响应,给太平洋暖事件的异常发展提供了有利条件;同样,热带太平洋暖事件通过对热带印度洋上空大气环流的影响,给印度洋偶极子的异常发展提供了有利条件。 相似文献
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Sea surface temperature (SST) variations include negative feedbacks from the atmosphere, whereas SST anomalies are specified in stand-alone atmospheric general circulation simulations. Is the SST forced response the same as the coupled response? In this study, the importance of air–sea coupling in the Indian and Pacific Oceans for tropical atmospheric variability is investigated through numerical experiments with a coupled atmosphere-ocean general circulation model. The local and remote impacts of the Indian and Pacific Ocean coupling are obtained by comparing a coupled simulation with an experiment in which the SST forcing from the coupled simulation is specified in either the Indian or the Pacific Ocean. It is found that the Indian Ocean coupling is critical for atmospheric variability over the Pacific Ocean. Without the Indian Ocean coupling, the rainfall and SST variations are completely different throughout most of the Pacific Ocean basin. Without the Pacific Ocean coupling, part of the rainfall and SST variations in the Indian Ocean are reproduced in the forced run. In regions of large mean rainfall where the atmospheric negative feedback is strong, such as the North Indian Ocean and the western North Pacific in boreal summer, the atmospheric variability is significantly enhanced when air–sea coupling is replaced by specified SST forcing. This enhancement is due to the lack of the negative feedback in the forced SST simulation. In these regions, erroneous atmospheric anomalies could be induced by specified SST anomalies derived from the coupled model. The ENSO variability is reduced by about 20% when the Indian Ocean air–sea coupling is replaced by specified SST forcing. This change is attributed to the interfering roles of the Indian Ocean SST and Indian monsoon in western and central equatorial Pacific surface wind variations. 相似文献
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Observations show that the summer precipitation over East China often goes through decadal variations of opposite sign over North China and the Yangtze River valley (YRV), such as the “southern flood and northern drought” pattern that occurred during the late 1970s–1990s. In this study it is shown that a modulation of the Pacific Decadal Oscillation (PDO) on the summer precipitation pattern over East China during the last century is partly responsible for this characteristic precipitation pattern. During positive PDO phases, the warm winter sea surface temperatures (SSTs) in the eastern subtropical Pacific along the western coast of North American propagate to the tropics in the following summer due to weakened oceanic meridional circulation and the existence of a coupled wind–evaporation–SST feedback mechanism, resulting in a warming in the eastern tropical Pacific Ocean (5°N–20°N, 160°W–120°W) in summer. This in turn causes a zonal anomalous circulation over the subtropical–tropical Pacific Ocean that induces a strengthened western Pacific subtropical high (WPSH) and thus more moisture over the YRV region. The end result of these events is that the summer precipitation is increased over the YRV region while it is decreased over North China. The suggested mechanism is found both in the observations and in a 600-years fully coupled pre-industrial multi-century control simulations with Bergen Climate Model. The intensification of the WPSH due to the warming in the eastern tropical Pacific Ocean was also examined in idealized SSTA-forced AGCM experiments. 相似文献
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Joint Impacts of SSTA in Tropical Pacific and Indian Oceans on Variations of the WPSH 总被引：2，自引：1，他引：1
Using the NCEP/NCAR reanalysis and HadISST sea surface temperature (SST) data, the joint effects of the tropical Indian Ocean and Pacific on variations of area of the summertime western Pacific subtropical high (WPSH) for period 1980–2016 are investigated. It is demonstrated that the central tropical Indian Ocean (CTI) and central equatorial Pacific (CEP) are two key oceanic regions that affect the summertime WPSH. During autumn and winter, warm SST anomalies (SSTAs) in CEP force the Walker circulation to change anomalously, resulting in divergence anomalies over the western Pacific and Maritime Continent (MC). Due to the Gill-type response, the abnormal anticyclonic circulation is generated over the western Pacific and South China Sea (SCS). In the subsequent spring, the warm SSTAs in CEP weaken, while the SST over CTI demonstrates a lagged response to Pacific SSTA. The warm CTISSTA and CEP-SSTA cooperate with the eastward propagation of cold Kelvin waves in the western Pacific, leading to the eastward shift of the abnormal divergence center that originally locates at the western Pacific and MC. The anticyclone forced by this divergence subsequently moves eastward, leading to the intensification of the negative vorticity there. Meanwhile, warm SSTA in CTI triggers eastward propagating Kelvin waves, which lead to easterly anomalies over the equatorial Indian Ocean and Indonesia, being favorable for maintenance and intensification of the anticyclone over the SCS and western Pacific. The monsoonal meridional–vertical circulation strengthens, which is favorable for the intensification of the WPSH. Using SSTA over the two key oceanic regions as predictors, a multiple regression model is successfully constructed for prediction of WPSH area. These results are useful for our better understanding the variation mechanisms of WPSH and better predicting summer climate in East Asia. 相似文献
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西北太平洋副热带高压(西太副高)是影响东亚夏季气候的主要环流系统,其年际变率受热带多个海区的海-气相互作用过程的调控。为明确影响夏季西太副高的关键海区及其影响机制,在总结最近十余年来相关研究进展的基础上,归纳出影响夏季西太副高年际变率的5个关键海区,包括赤道中东太平洋、热带印度洋、副热带西北太平洋、海洋大陆附近海区以及热带大西洋。阐述了这5个关键海区的海温异常影响西太副高年际变率的机制,并探讨了5个关键海区海温异常的形成机制。围绕夏季西太副高的年际变率,回顾了当前气候模式的模拟和预测研究的现状。最后,提出了本领域亟待解决的关键科学问题,展望未来可能的研究热点。 相似文献
20.
A numerical experiment of an asynchronous coupled ocean-atmosphere model has been described in this paper.A two-layer global atmosphere general circulation model(OSU/IAP-AGCM)and a two-layer North Pacific Ocean general circulation model(NPOGCM) developed by Liu et al.(1992)are used in numerical experiment.The sea surface temperature anomaly(SSTA) corresponding to the meander of the Kuroshio is treated as the initial perturbation in the Pacific Ocean and the abnormal phenomena caused by the disturbance and the interaction between atmosphere and ocean,have been studied.The numerical experiment showed that the SST anomaly in the North Pacific could induce a new 30-60 day osciltation through the coupling between atmosphere and ocean and the interaction between the meander of the Kuroshio and atmosphere circulation is a positive feedback process. 相似文献