中国东部降水年际变化的随机动力诊断

利用一个具有门限的非线性随机动力气候模式对中国东部江淮流域的降水进行了分析。结果表明：在不同的门限域中,降水对外部强迫的响应有明显差异,呈现出一定的非线性特征;模式能较好地拟合降水的变化趋势。     

中国东部降水的随机动力预测初步研究

利用一个具有门限的非线性随机动力气候模式,对中国东部江淮流域的降水进行了预报试验。结果表明：模式能对大范围环流降水作出较为准确的形势预报。还比较了海气耦合模式与外强迫模式的预报效果,表明耦合模式的预报效果略好于外强迫模式。     

气候集成预报的初步探讨

将气候集成预报的ＭｏｎｔｅＣａｒｌｏｓ模拟方法应用到带有门限的海气耦合随机动力模式中。利用相空间概念确定报误差,对不同相变量初值随机扰动的概率密度分布函数以及ＭｏｎｔｅＣａｒｌｏ模拟的集成样本数进行了最佳选择试验。     

一非线性统计－动力气候模式及其降水预报试验

在带有线性反馈的统计－动力气候模式的基础上，提出了一种非线性统计－动力气候模式。该模式的实质是用逐段线性化的统计－动力气候模式来描述气候系统的总体非线性变化特征。试验结果表明，该模式能更客观地预测气候变化     

一非线性统计—动力气候模式及其降水预报试验

在带有线性反馈的统计－动力气候模式的基础，提出了一种非线性统计－动力气候模式，该模式的实质是用逐段线性化的统计－动力气候模式来描述气候系统的总体非线性特征。试验结果表明，该模式能更客观地预测气候变化。     

广东气温变化与南方涛动关系的随机动力分析

本文推导出二维线性和非线性随机动力模式的Fokker—Planck方程,得到其稳定态的解析解和气候势函数,并应用于广东气温和南方涛动的随机分析。计算结果表明,线性模式能明确反映广东气温和南方涛动之间的反馈关系;非线性模式则表明非线性作用使广东气温和南方涛动之间的稳定平衡更趋于合理化。      

应用自激励门限自回归模式对旱涝游程序列的模拟和预报

在用AR、ARMA等线性模式对气候序列进行拟合和预报时,由于气候序列中存在着非线性变化,所以拟合和预报效果往往不太理想。本文首次用非线性自激励门限自回归模式(SETAR)对由北京511年(1470—1980年)历史旱涝记录变换的湿涝(干旱)游程记录进行了模拟和预报,解决了长期以来预报方程不能随转折点变更的问题。拟合和预报结果表明:门限自回归模式的拟合和预报效果比线性AR模式有明显提高。AR模式只能预报出2年长度以下的游程转折点,而SETAR模式能较准确地预报出3年长度以上的游程转折点。这可能是因为在预报过程中SETAR模式能按游程转折点更新模式,而且模式建立时不要求序列具有平稳性的缘故。     

我国短期气候动力预测模式系统的研究及试验

气候和气候异常对我国的国民经济发展具有重大影响,为提高短期气候预测的准确率,研究动力气候模式短期气候预测新技术至关重要.通过近5年的努力,建立了一套出月动力延伸预报模式,海气耦合的全球气候模式(AGCM+OGCM+海冰+高分辨率印度洋-太平洋海盆模式),区域气候模式季和年际尺度的业务动力模式组成的系统.初步把我国的短期气候预测水平由经验统计方法提高到定量和客观分析的水平上.在此基础上,已建成了一个具有物理基础的统计方法与气候动力模式相结合的综合气候预报系统.     

气候系统的非线性特征及其预测理论

本文针对气候问题的特殊性,对气候的定义、气候系统的非线性特征、演变机制、可预报性问题以及气候状态的预报方法等做了较全面的研究,这些内容初步形成了气候系统的准动力—准随机理论,是气候动力学的新发展。     

随机——非线性气候模式初探

本文通过对地球实测辐射过程的分析,建立了能量平衡气候模式和随机气候模式,并通过求解模式,初步说明了控制气候的各主要物理过程的作用和相互关系。认为辐射过程中的非线性作用将使气候产生多平衡状态和突变,而天气系统的随机强迫则会导致气候温度发生偏离。最后,将运用本文的理论结果对冰期—间冰期转换的可能机制作出一定的解释。     

Robust GEFA Assessment of Climate Feedback to SST EOF Modes

Atmospheric response to SST variability was estimated using generalized equilibrium feedback analysis (GEFA) in the SST EOF space with synthesis data from an idealized climate model. Results show that the GEFA atmospheric response to the leading SST EOF modes is much more accurate and robust than the GEFA feedback matrix in physical space. Therefore, GEFA provides a practical method for assessing atmospheric response to large-scale SST anomalies in terms of the leading EOFs.     

青藏高原感热加热对7月份大气环流和亚洲夏季风影响的数值试验

根据低纬地区地表温度高、蒸发及降水量大、辐合上升运动剧烈等特点,本文构造了一个正压模式的方程组,提示出影响低纬大气波动的一个重要因素——海表温度SST。研究指出:(1)当SST<25℃时,含蒸发风反馈机制的Rossby波向西传播,当SST>25℃时.含蒸发风反馈机制的Rossby波向东传播。(2)SST的数值越高,空气越潮湿,含蒸发风反馈机制的Rossby波传播速度就越小。当SST超过29℃时,会形成周期为30天的低频振荡。     

Dynamic Linkage between the North Pacific and the Tropical Pacific: Atmosphere-Ocean Coupling

In this study, dynamic linkage of atmosphere-ocean coupling between the North Pacific and the tropical Pacific was demonstrated using a large number of ensemble perturbed initial condition experiments in a fully coupled fast ocean-atmosphere model (FOAM). In the FOAM model, an idealized mixed layer warming was initiated in the Kuroshio-Oyashio extension region, while the ocean and atmosphere remained fully coupled both locally and elsewhere. The modeling results show that the warm anomalies are associated with anomalous cyclonic winds, which induce initial warming anomalies extending downstream in the following winter. Then, the downstream warming spreads southwestward and induces SST warming in the equatorial Pacific via surface wind-evaporation-SST feedback. Warming in the tropical Pacific is further reinforced by Bjerknes’ feedback.     

区域气候模式与陆面模式的耦合及其对东亚气候模拟的影响

将大气—植被相互作用模式AVIM（Atmosphere-Vegetation Interaction Model）与区域环境系统集成模式 RIEMS2.0（Regional Integrated Environment Modeling System Version 2.0）耦合,利用耦合后的AVIM-RIEMS2.0模式在东亚区域选定典型年份进行积分试验,通过模拟结果与观测资料对比分析,从整体上评估耦合模式对东亚区域的模拟能力。结果表明:模式能够较好地模拟850 hPa风场、500 hPa位势高度、气温、降水以及地表热通量空间分布型和季节变化。双向耦合具有动态植被过程的AVIM模式后,RIEMS2.0模拟能力有一定程度的提高。850 hPa风场在冬季的中国东北、华北地区以及夏季的中国东部地区,模拟偏差都减小;500 hPa高度场模拟在中国北方地区改进明显,而在中国南方地区的夏季并没表现出明显的改进趋势。耦合模式改进了RIEMS2.0模式冬季气温模拟偏低而夏季偏高的现象。从区域平均看,耦合模式改善了降水模拟偏多的现象,并使得潜热通量的模拟效果有明显的改进,对感热通量模拟在大部分地区也有改进。总的来看,AVIM-RIEMS2.0耦合模式对中国北方地区模拟改进较为明显,而对中国南方地区,特别是华南地区没有明显的改进。     

Vegetation Feedback at the Mid-Pliocene

A global atmospheric general circulation model and an asynchronously coupled global atmosphere-biome model are used to simulate vegetation feedback at the mid-Pliocene approximately 3.3 to 3.0 million years ago.For that period,the simulated vegetation differed from present conditions at 62%of the global ice-free land surface.Vegetation feedback had little overall impact on the global climate of the mid-Pliocene.At the regional scale,however,the interactive vegetation led to statistically significant increases in annual temperature over Greenland,the high latitudes of North America,the mid-high latitudes of eastern Eurasia,and western Tibet,and reductions in most of the land areas at low latitudes,owing to vegetation-induced changes in surface albedo.     

A DIAGNOSTIC STUDY OF FEEDBACK MECHANISM IN GREENHOUSE EFFECTS SIMULATED BY NCAR CCM1

This paper describes a diagnostic study of the feedback mechanism in greenhouse effects of increased CO_2 and oth-er trace gases(CH_4,N_2O and CFCs),simulated by general circulation model.The study is based on two sensitivity exper-iments for doubled CO_2 and the inclusion of other trace gases,respectively,using version one of the community climatemodel(CCM1)developed at the National Centre for Atmospheric Research.A one-dimensional(1-D)and atwo-dimensional(2-D)radiative-convective models are used to diagnose the feedback effect.It shows that thefeedback factors in global and annual mean conditions are in the sequence of surface albedo,water vapor amount,watervapor distribution,cloud height,critical lapse rate and cloud cover,while in zonal and annual mean conditions in thetropical region the above sequence does not change except the two water vapor terms being the largest feedback compo-nents.Among the feedback components,the total water vapor feedback is the largest(about 50%).The diagnosis alsogives a very small feedback of either the cloud cover or the lapse rate,which is substantially different from the 1-Dfeedback analysis by Hansen et al.(1984).The small lapse rate feedback is considered to be partly caused by theconvective adjustment scheme adopted by CCM1 model.The feedback effect for doubled CO_2 is very different from that of the addition of other trace gases because of theirdifferent vertical distributions of radiative forcing although the non-feedback responses of surface air temperature forboth cases are almost the same.For instance,the larger forcing at surface by the addition of other trace gases can causestronger surface albedo feedback than by doubled CO_2.Besides,because of the negative forcing of doubled CO_2 in thestratosphere,cloud height feedback is more intense.The larger surface forcing in the case of other trace gases can also in-fluence atmospheric water vapor amount as well as the water vapor distribution,which will in turn have strongerfeedback effects.All these indicate that it is incorrect to use“effective CO_2”to replace other trace gases in the generalcirculation model.     

Cloud feedback on sst variability in the western equatorial pacific in goals / lasg model

The cloud feedback on the SST variability in the western equatorial Pacific in GOALS / LASG model is studied in this paper. Two versions of the model, one with the diagnostic cloud and another with the prescribed cloud, are used. Both versions are integrated for 45 years. It is found that in the prescribed cloud run, the SST variability in the western equatorial Pacific is mainly of interdecadal time scale and the interannual variability is very weak. In the diagnostic cloud run, however, the interdecadal SST variability is depressed much and the interannual SST variability becomes much significant. The mechanism for the feedback is then explored. The variability of sea surface temperature (SST) in the western equatorial Pacific is found to be controlled mainly by the zonal wind anomaly, through the process of upwelling / downwelling in both versions. Then it is found that in the diagnostic cloud case, the negative feedback of the solar short wave (SW) flux acts significantly to balance the effect of upwelling / downwelling in addition to the latent flux. In addition, the variability of the SW flux is shown to be closely related to the variability of the middle and high cloud covers. Therefore, the negative feedback of the SW surface flux may have significant contribution to the cloud feedback on the SST variability.     

边界层急流与北京局地强降水关系的数值研究

应用3 km分辨率的中尺度模式,成功模拟出了2005年8月3日凌晨北京地区一次局地强降水过程,在此基础上探讨了地形热力作用和局地强降水与边界层急流的关系,结果表明,局地强降水与边界层急流之间存在正反馈作用,降水过程通过改变局地大气温度场的分布,导致边界层气流加速和急流的形成。而边界层气流的加速又加强了急流前方的风速辐合,为降水提供更多的水汽和更有利的动力条件。     

FGOALS-g模式及其参与CMIP6的方案

为参加第六次国际耦合模式比较计划（CMIP6）和进一步提高模式的模拟能力,大气科学和地球流体力学数值模拟国家重点实验室（LASG）模式团队发展了新一代的格点大气版本的FGOALS-g耦合模式。新版本模式在大气分辨率、海洋网格,以及各分量模式的物理过程等方面都有一定的改进,并正在参与CMIP6最核心的试验以及多个CMIP6模式比较子计划试验。给定CMIP6外强迫,模式在工业革命前参照试验（piControl）和大气模式比较计划（AMIP）试验中模拟的初步结果都比较合理。     

Dynamical Feedback between Synoptic Eddy and Low-Frequency Flow as Simulated by BCC_CSM1.1(m)

Since the interaction between atmospheric synoptic eddy(SE)(2–8 days) activity and low-frequency(LF)(monthly)flow(referred to as SELF) plays an essential role in generating and maintaining dominant climate modes,an evaluation of the performance of BCC_CSM1.1(m) in simulating the SE feedback onto the LF flow is given in this paper.The model captures well the major spatial features of climatological eddy vorticity forcing,eddy-induced growth rate,and patterns of SELF feedback for the climate modes with large magnitudes in cold seasons and small magnitudes in warm seasons for both the Northern and Southern Hemisphere.As in observations,the eddy-induced growth rate and SELF feedback patterns in the model also show positive SE feedback.Overall,the relationships between SE and LF flow show that BCC_CSM1.1(m)satisfactorily captures the basic features of positive SE feedback,which demonstrates the simulation skill of the model for LF variability.Specifically,such an evaluation can help to find model biases of BCC_CSM1.1(m) in simulating SE feedback,which will provide a reference for the model's application.