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1.
This study examines cloud radiative forcing (CRF) in the Asian monsoon region
(0o--50oN,60o--150oE) simulated by Intergovernmental Panel on
Climate Change (IPCC) Fourth Assessment Report (AR4) AMIP models. During boreal winter,
no model realistically reproduces the larger long-wave cloud radiative forcing (LWCF) over
the Tibet Plateau (TP) and only a couple of models reasonably capture the larger short-wave
CRF (SWCF) to the east of the TP. During boreal summer, there are larger biases for central
location and intensity of simulated CRF in active convective regions. The CRF biases are closely
related to the rainfall biases in the models. Quantitative analysis further indicates that the
correlation between simulated CRF and observations are not high, and that the biases and diversity
in SWCF are larger than that in LWCF. The annual cycle of simulated CRF over East Asia (0o--50oN,
100o--145oE) is also examined. Though many models capture the basic annual cycle in
tropics, strong LWCF and SWCF to the east of the TP beginning in early spring are underestimated
by most models. As a whole, GFDL-CM2.1, MPI-ECHAM5, UKMO-HadGAM1, and MIROC3.2 (medres) perform
well for CRF simulation in the Asian monsoon region, and the multi-model ensemble (MME) has improved
results over the individual simulations. It is suggested that strengthening the physical
parameterizations involved over the TP, and improving cumulus convection processes and model
experiment design are crucial to CRF simulation in the Asian monsoon region. 相似文献
2.
This study examines the variability of the South America monsoon system (SAMS) over tropical South America (SA). The onset, end, and total rainfall during the summer monsoon are investigated using precipitation pentad estimates from the global precipitation climatology project (GPCP) 1979–2006. Likewise, the variability of SAMS characteristics is examined in ten Intergovernmental Panel on Climate Change (IPCC) global coupled climate models in the twentieth century (1981–2000) and in a future scenario of global change (A1B) (2081–2100). It is shown that most IPCC models misrepresent the inter-tropical convergence zone and therefore do not capture the actual annual cycle of precipitation over the Amazon and northwest SA. Most models can correctly represent the spatiotemporal variability of the annual cycle of precipitation in central and eastern Brazil such as the correct phase of dry and wet seasons, onset dates, duration of rainy season and total accumulated precipitation during the summer monsoon for the twentieth century runs. Nevertheless, poor representation of the total monsoonal precipitation over the Amazon and northeast Brazil is observed in a large majority of the models. Overall, MIROC3.2-hires, MIROC3.2-medres and MRI-CGCM3.2.3 show the most realistic representation of SAMS’s characteristics such as onset, duration, total monsoonal precipitation, and its interannual variability. On the other hand, ECHAM5, GFDL-CM2.0 and GFDL-CM2.1 have the least realistic representation of the same characteristics. For the A1B scenario the most coherent feature observed in the IPCC models is a reduction in precipitation over central-eastern Brazil during the summer monsoon, comparatively with the present climate. The IPCC models do not indicate statistically significant changes in SAMS onset and demise dates for the same scenario. 相似文献
3.
亚洲夏季风的年际和年代际变化及其未来预测 总被引：31，自引：12，他引：19
本文是对我们近五年在亚洲夏季风年代际与年际变率及其未来预测方面研究的一个综述.主要包括下列三个问题:(1)根据123年中国夏季降水资料和印度学者的分析,检测出亚洲夏季风具有明显的年代际尺度减弱,这种年代际变化使中国东部(包括东亚)和南亚夏季降水的格局在过去60年中发生了明显变化.在东亚,从1970年代后期开始,主要异常雨带有不断南移的趋势,结果造成了南涝北旱的降水分布,这主要受到60～80年年代际振荡的影响.青藏高原前冬和春季积雪的年代际减少与热带中东太平洋海表温度的年代际增加是东亚降水型改变的主要原因,这是通过减弱亚洲地区夏季海陆温差与夏季风强度而实现的.未来亚洲夏季风的预测表明,东亚夏季风和南亚夏季风对气候变暖有十分不同的响应.东亚夏季风在本世纪将增强,雨带北推,尤其在2040年代之后;而南亚夏季风环流将继续减弱.这种不同的变化是由于两者对高低层海陆热力差异的不同响应造成.(2)年际尺度的变率在亚洲夏季风区主要表现为2年与4～7年的振荡.本文着重分析了2年振荡(TBO)形成的过程、机理及其对东亚降水的影响.对TBO-海洋机理进行了具体的改进,说明了东亚夏季风降水深受TBO影响的原因,尤其是阐明了长江型(YRV) TBO和淮河型(HRV) TBO的特征及其形成的循环过程.(3)在总结亚洲夏季风时期遥相关型的基础上,本文提出了季节内和年际尺度的低空遥相关型:即西北太平洋季风的遥相关型与印度“南支”和“北支”遥相关型.它们基本上反映了沿低空夏季风强风速带Rossby波群速度传播的结果.据此可以根据西北太平洋和印度夏季风的变化分别预测中国梅雨和华北雨季来临和降水异常.最后研究还表明,在本世纪亚洲夏季风可能更显著地受到人类活动造成的全球变暖的影响,未来的亚洲夏季风活动是人类排放的CO2引起的全球变暖与自然变化(海洋和陆面过程(积雪))共同作用的结果. 相似文献
4.
全球海气耦合模式对东亚季风降水模拟的检验 总被引：19，自引：6，他引：13
以CMAP(Climate Prediction Center Merged Analysis of Precipitation)月平均降水资料和欧洲中期天气预报中心（ECMWF）的40年再分析资料集ERA40为观测基础,分析了当前政府间气候变化专门委员会第四次评估报告（IPCC AR4）的17个全球海气耦合模式对东亚季风区夏季降水和环流的模拟能力。结果表明:(1)模式基本上都能够模拟出降水由东亚东南部海洋至东亚西北部中国内陆减少的空间分布特征,部分模式能够模拟出降水的部分主要模态;(2) 大部分模式基本上能够模拟出中国东部陆地降水的季节进退。但同时也存在相当的差异,这包括:(1)多数模式普遍存在模拟降水量偏少、降水变幅偏小的缺陷;(2)雨带的季节推进过程与观测存在一定偏差,尤其海洋上的季节进退过程模拟较差,有的模式甚至不能模拟出东亚季风区东部海洋上大致的季节进程。因此,模式对东亚季风区降水的模拟能力还是比较有限的,需要进一步改进。多模式集合的夏季环流场以偏弱为主,不利于降水的形成,这在中国东部大陆部分比较明显。另外,空气湿度模拟值偏低、从而造成水汽输送偏弱也是导致东亚季风区夏季降水模拟偏小的原因之一。 相似文献
5.
CMIP5气候模式对中国东部夏季降水年代际变化的模拟性能评估 总被引：9，自引：2，他引：7
使用分类集合的方法评估了第五次耦合模式比较计划(CMIP5)多个耦合模式对中国东部夏季降水年代际变化的模拟性能.结果表明,在评估的38个模式中,仅有6个模式(第1类模式)可以成功再现1970年代末中国东部夏季降水年代际变化的主要特征,即长江流域降水偏多、而华北和华南偏少.这些模式模拟的成功归因于它们能较好再现1970年代末东亚夏季风的年代际减弱及相关的环流场的变化,包括东亚沿海的偏北风异常以及西太平洋副热带高压的偏向西南、强度增强等.而对降水年代际变化模拟很差的第2类模式,则模拟出不出东亚夏季风的这种减弱特征.进一步的分析表明,两类CMIP5模式对太平洋年代际振荡(PDO)空间分布特征都有较好的再现能力,但对PDO年代际转变特征的模拟能力则差异较大.第1类模式能很好地模拟出1970年代末热带海洋的增暖和相关的PDO位相由负到正的转换,而第2类模式所模拟的PDO位相转变与观测完全相反,且也不能模拟出热带中东太平洋海洋的年代际增暖及江淮流域夏季的变冷,因此导致该类模式对1970年代末东亚夏季风的减弱和中国东部夏季雨型的年代际转变没有模拟能力.由此也表明,对耦合模式来说,中国夏季降水年代际变化的模拟能力在很大程度上取决于模式对海洋年代际变化信号的模拟. 相似文献
6.
Possible Impacts of the Arctic Oscillation on the Interdecadal Variation of Summer Monsoon Rainfall in East Asia 总被引：18，自引：5，他引：18
The influences of the wintertime AO (Arctic Oscillation) on the interdecadal variation of summer monsoon rainfall in East Asia were examined. An interdecadal abrupt change was found by the end of the 1970s in the variation of the AO index and the leading principal component time series of the summer rainfall in East Asia, The rainfall anomaly changed from below normal to above normal in central China, the southern part of northeastern China and the Korean peninsula around 1978. However,the opposite interdecadal variation was found in the rainfall anomaly in North China and South China.The interdecadal variation of summer rainfall is associated with the weakening of the East Asia summer monsoon circulation. It is indicated that the interdecadal variation of the AO exerts an influence on the weakening of the monsoon circulation. The recent trend in the AO toward its high-index polarity during the past two decades plays important roles in the land-sea contrast anomalies and wintertime precipitation anomaly. The mid- and high-latitude regions of the Asian continent are warming, while the low-latitude regions are cooling in winter and spring along with the AO entering its high-index polarity after the late 1970s. In the meantime, the precipitation over the Tibetan Plateau and South China is excessive, implying an increase of soil moisture. The cooling tendency of the land in the southern part of Asia will persist until summer because of the memory of soil moisture. So the warming of the Asian continent is relatively slow in summer. Moreover, the Indian Ocean and Pacific Ocean which are located southward and eastward of the Asian land, are warming from winter to summer. This suggests that the contrast between the land and sea is decreased in summer. The interdecadal decrease of the land-sea heat contrast finally leads to the weakening of the East Asia summer monsoon circulation. 相似文献
7.
INTERDECADAL VARIATIONS OF INTERACTION BETWEEN NORTH PACIFIC SSTA AND EAST ASIAN SUMMER MONSOON 总被引：1，自引：0，他引：1
Identification of key SST zones is essential in predicting the weather / climate systems in East
Asia. With the SST data by the U.K. Meteorological Office and 40-year geopotential height and wind fields by
NCAR / NCEP, the relationship between the East Asian summer monsoon and north Pacific SSTA is studied,
which reveals their interactions are of interdecadal variation. Before mid-1970's, the north Pacific SSTA acts
upon the summer monsoon in East Asia through a great circle wavetrain and results in more rainfall in the
summer of the northern part of China. After 1976, the SSTA weakens the wavetrain and no longer influences
the precipitation in North China due to loosened links with the East Asian summer monsoon. It can be drawn
that the key SST zones having potential effects on the weather / climate systems in East Asia do not stay in one
particular area of the ocean but rather shift elsewhere as governed by the interdecadal variations of the air-sea
interactions. It is hoped that the study would help shed light on the prediction of drought / flood spans in China. 相似文献
8.
Statistical Downscaling for Multi-Model Ensemble Prediction
of Summer Monsoon Rainfall in the Asia-Pacific
Region Using Geopotential Height Field 总被引：16，自引：1，他引：15
The 21-yr ensemble predictions of model precipitation and circulation in the East Asian and western North Pacific （Asia-Pacific） summer monsoon region （0°-50°N, 100° 150°E） were evaluated in nine different AGCM, used in the Asia-Pacific Economic Cooperation Climate Center （APCC） multi-model ensemble seasonal prediction system. The analysis indicates that the precipitation anomaly patterns of model ensemble predictions are substantially different from the observed counterparts in this region, but the summer monsoon circulations are reasonably predicted. For example, all models can well produce the interannual variability of the western North Pacific monsoon index （WNPMI） defined by 850 hPa winds, but they failed to predict the relationship between WNPMI and precipitation anomalies. The interannual variability of the 500 hPa geopotential height （GPH） can be well predicted by the models in contrast to precipitation anomalies. On the basis of such model performances and the relationship between the interannual variations of 500 hPa GPH and precipitation anomalies, we developed a statistical scheme used to downscale the summer monsoon precipitation anomaly on the basis of EOF and singular value decomposition （SVD）. In this scheme, the three leading EOF modes of 500 hPa GPH anomaly fields predicted by the models are firstly corrected by the linear regression between the principal components in each model and observation, respectively. Then, the corrected model GPH is chosen as the predictor to downscale the precipitation anomaly field, which is assembled by the forecasted expansion coefficients of model 500 hPa GPH and the three leading SVD modes of observed precipitation anomaly corresponding to the prediction of model 500 hPa GPH during a 19-year training period. The cross-validated forecasts suggest that this downscaling scheme may have a potential to improve the forecast skill of the precipitation anomaly in the South China Sea, western North Pacific and the East Asia Pacific regions, wh 相似文献
9.
The sensitivity of the representation of the global monsoon annual cycle to horizontal resolution is compared in three AGCMs:the Met Office Unified Model-Global Atmosphere 3.0;the Meteorological Research Institute AGCM3;and the Global High Resolution AGCM from the Geophysical Fluid Dynamics Laboratory.For each model,we use two horizontal resolution configurations for the period 1998–2008.Increasing resolution consistently improves simulated precipitation and low-level circulation of the annual mean and the first two annual cycle modes,as measured by the pattern correlation coefficient and equitable threat score.Improvements in simulating the summer monsoon onset and withdrawal are region-dependent.No consistent response to resolution is found in simulating summer monsoon retreat.Regionally,increased resolution reduces the positive bias in simulated annual mean precipitation,the two annual-cycle modes over the West African monsoon and Northwestern Pacific monsoon.An overestimation of the solstitial mode and an underestimation of the equinoctial asymmetric mode of the East Asian monsoon are reduced in all high-resolution configurations.Systematic errors exist in lower-resolution models for simulating the onset and withdrawal of the summer monsoon.Higher resolution models consistently improve the early summer monsoon onset over East Asia and West Africa,but substantial differences exist in the responses over the Indian monsoon region,where biases differ across the three low-resolution AGCMs.This study demonstrates the importance of a multi-model comparison when examining the added value of resolution and the importance of model physical parameterizations for simulation of the Indian monsoon. 相似文献
10.
Future changes in East Asian summer monsoon precipitation climatology, frequency, and intensity are analyzed using historical climate simulations and future climate simulations under the RCP4.5 scenario using the World Climate Research Programme’s (WCRP) Coupled Model Intercomparison Project 5 (CMIP5) multi-model dataset. The model reproducibility is evaluated, and well performance in the present-day climate simulation can be obtained by most of the studied models. However, underestimation is obvious over the East Asian region for precipitation climatology and precipitation intensity, and overestimation is observed for precipitation frequency. The overestimation of precipitation frequency is mainly due to the large positive bias of the light precipitation (precipitation <10 mm/day) days, and the underestimation of precipitation intensity is mainly caused by the negative bias of the intense precipitation (precipitation >10 mm/day) intensity. For the future climate simulations, simple multi-model ensemble (MME) averages using all of the models show increases in precipitation and its intensity over almost all of East Asia, while the precipitation frequency is projected to decrease over eastern China and around Japan and increase in other regions. When the weighted MME is considered, no large difference can be observed compared with the simple MME. For the MME using the six best models that have good performance in simulating the present-day climate, the future climate changes over East Asia are very similar to those predicted using all of the models. Further analysis shows that the frequency and intensity of intense precipitation events are also projected to significantly increase over East Asia. Increases in precipitation frequency and intensity are the main contributors to increases in precipitation, and the contribution of frequency increases (contributed by 40.8 % in the near future and by 58.9 % by the end of the twenty-first century) is much larger than that of intensity increases (contributed by 29.9 % in the near future and by 30.1 % by the end of the twenty-first century). This finding also implies an increased risk of intense precipitation events over the East Asian region under global warming scenario. These results regarding future climate simulations show much greater reliability than those using CMIP3 simulations. 相似文献
11.
对CMIP5全球气候模式中年代际回报试验的气温资料及其简单集合平均(Multi-model ensemble mean,EMN)和贝叶斯模式平均的结果(Bayesian Model Averaging,BMA)进行经验正交函数(Empirical Orthogonal Function,EOF)分解和Morlet小波分析,检验评估各个模式及其EMN和BMA对东亚地面气温的方差、气温时空分布特征及周期变化的回报能力。结果表明,10个模式、EMN、BMA都能很好地回报出1981—2010年东亚地面气温的方差分布,其中BMA回报效果最好。EOF分析表明,BMA能较好地回报出东亚地面气温第一模态的时空分布。MIROC5能较好地回报出第二模态的趋势变化,但却不能回报出气温的年际变率。绝大多数模式和EMN、BMA虽然能回报出东亚地面气温的变化趋势,但是对气温年际变率的回报仍然是比较困难的。CMCC-CM对气温变化主模态的3~5 a的周期变化特征回报效果最好,和NCEP资料的结果最为接近。 相似文献
12.
In order to investigate changes in the East Asian summer monsoon (EASM) under the global warming, the MIROC3.2 (hires) coupled general circulation model (CGCM) developed by the Center for Climate System Research is utilized. The outputs of MIROC3.2 (hires) model have been analyzed using two scenarios; the 20th Century Climate in Coupled Models (20C3M) scenario and the Special Reports for Emissions Scenarios A1B (SRES A1B). Eight Intergovernmental Panel on Climate Change (IPCC) models are also analyzed to compare model performances. It is shown that the simulation skill of MIROC3.2 (hires) for the EASM is relatively superior to these IPCC CGCMs. It has been found that the intensified rain band and the extended duration of the EASM are anticipated with MIROC3.2 (hires) under the global warming in well accordance with previous studies. Especially, the precipitation due to the cumulus convection is predicted to increase more significantly than the precipitation by the large-scale condensation. Due to the increased land-sea thermal contrast in summer under the global warming, water vapor fluxes in the lower troposphere are enhanced. Consequently, the convective instability may be strengthened and thus it leads to the increase of precipitation by cumulus convection. Moreover, the upper tropospheric circulations associated with the EU pattern would lead to the larger interannual variability of precipitation over the EASM region in the future warm climate. In addition, it is found that the relationship between the sea surface temperature over the tropical Pacific Ocean in the wintertime and the summer rainfall over the East Asia may be weakened, suggesting that the predictability of the EASM might become more difficult under the global warming. 相似文献
13.
Summary The East Asian (China, Korea and Japan) summer monsoon precipitation and its variability are examined from the outputs of
the coupled climate models performing coordinated experiments leading to the Intergovernmental Panel on Climate Change Fourth
Assessment Report (IPCC AR4). Out of the 22 models examined, 14 reproduce the observed shape of the annual cycle well with
peak during the boreal summer (June through August), but with varying magnitude. Three models simulate the maximum a month
later and with lower magnitudes. Only one model considerably underestimates the magnitude of the annual cycle. The remaining
4 models show some deviations from the observed. Models are unable to simulate the minimum in July with peaks in June and
August associated with northward shifts of the Meiyu-Changma-Baiu precipitation band. The realistic simulation of the annual cycle does not appear to depend on the model resolution. The inter-model
variation is slightly larger during summer, implying larger diversity of the models in simulating summer monsoon precipitation.
The spatial rainfall patterns are reasonably well simulated by most of the models, with several models able to simulate the
precipitation associated with the Meiyu-Changma-Baiu frontal zone and that associated with the location of the subtropical high over the north Pacific. Simulated spatial distribution
could be sensitive to model resolution as evidenced by two versions of MIROC3.2 model. The multi-model ensemble (MME) pattern
reveals an underestimation of seasonal precipitation over the east coast of China, Korea-Japan peninsular and the adjoining
oceanic regions. This may be related with the mass-flux based scheme employed for convective parameterization by majority
of the models. Further the inter-model variation of precipitation is about 2 times stronger south of 30° N, than north of
this latitude, indicating larger diversity of the coupled models in simulating low latitude precipitation. The simulated inter-annual
variability is estimated by computing the mean summer monsoon seasonal rainfall and the coefficient of variability (CV). In
general the mean observed seasonal precipitation of 542 mm and CV of 6.7% is very well simulated by most of the models. Except
for one model mean seasonal precipitation varies from 400 to 650 mm. However the CV varies from 2 to 9%.
Future projections under the radiative forcing of doubled CO2 scenario are examined for individual models and by the MME technique. Changes in mean precipitation and variability are tested
by the t-test and F-ratio respectively to evaluate their statistical significance. The changes in mean precipitation vary from −0.6% (CNRM-CM3)
to about 14% (ECHO-G; UKMO-HadCM3). The MME technique reveals an increase varying from 5 to 10%, with an average of 7.8% (greater
than the observed CV of 6.7%) over the East Asian region. However the increases are significant over the Korea-Japan peninsula
and the adjoining north China region only. The increases may be attributed to the projected intensification of the subtropical
high, Meiyu-Changma-Baiu frontal zone and the associated influx of moist air from the Pacific inland. The projected changes in the amount of precipitation
are directly proportional to the projected changes in the strength of the subtropical high. Further the MME suggests a possible
increase in the length of the summer monsoon precipitation period from late spring through early autumn. The changes in precipitation
could be stabilized by controlling the CO2 emissions. 相似文献
14.
基于气温和降水观测资料以及美国国家环境预报中心/国家大气研究中心（NCEP/NCAR）大气再分析资料,系统评估了大样本初始化十年际预测试验（CESM-DPLE）对1959—2016年东亚夏季气候预测的能力。结果表明,CESM-DPLE能较好地模拟东亚夏季气候以及相关主要大气环流系统的基本态特征,在年际尺度上对东亚气温有很高的预测技巧但对降水几乎没有预测能力。CESM-DPLE再现了北大西洋多年代际振荡（AMO）经由激发遥相关波列所引起的中高纬度大气环流、东亚夏季风和气候的异常。20世纪90年代末之后,北大西洋多年代际振荡由冷位相转为暖位相,遥相关波列位相调整,东亚受异常低压控制,东亚夏季风偏强,夏季气温偏高、降水偏多。总体上,尽管还存在着不足,但CESM-DPLE对东亚夏季温度年际变化以及与20世纪90年代末北大西洋多年代际振荡位相转变相联的东亚夏季气候年代际变化具备一定的预测能力,是目前研究和预测东亚气候变化的一套较好试验数据。 相似文献
15.
We compare the ability of coupled global climate models from the phases 5 and 6 of the Coupled Model Intercomparison Project(CMIP5 and CMIP6, respectively) in simulating the temperature and precipitation climatology and interannual variability over China for the period 1961–2005 and the climatological East Asian monsoon for the period1979–2005. All 92 models are able to simulate the geographical distribution of the above variables reasonably well.Compared with earlier CMIP5 models, current CMIP6 models have nationally weaker cold biases, a similar nationwide overestimation of precipitation and a weaker underestimation of the southeast–northwest precipitation gradient, a comparable overestimation of the spatial variability of the interannual variability, and a similar underestimation of the strength of winter monsoon over northern Asia. Pairwise comparison indicates that models have improved from CMIP5 to CMIP6 for climatological temperature and precipitation and winter monsoon but display little improvement for the interannual temperature and precipitation variability and summer monsoon. The ability of models relates to their horizontal resolutions in certain aspects. Both the multi-model arithmetic mean and median display similar skills and outperform most of the individual models in all considered aspects. 相似文献
16.
本文根据政府间气候变化委员会 (IPCC) 第四次评估报告 (AR4) (简称IPCC-AR4) 中22个耦合模式对20世纪气候模拟 (20C3M) 结果中20世纪晚期亚洲夏季风降水的模拟所显示出各模式模拟能力的较大空间差异, 提出了一种滑动窗区空间相关系数来量化表征这种空间差异特征, 结果表明, 该系数明显优于传统空间相关系数, 其空间分布能够较为细致地描述各模式对较小区域模拟性能的空间差异特征。在此基础上, 本文提出以这种滑动窗区空间相关系数作为各模式的权重系数进行加权集合平均, 并称之为滑动窗区空间相关系数加权集合方法。利用该方法对IPCC-AR4 22个耦合模式所模拟的20世纪晚期亚洲夏季风降水进行加权集合平均, 并将其结果与传统空间相关系数加权集合平均以及等权重多模式集合平均结果进行比较, 表明了利用本文所提出的加权集合方法对20世纪晚期亚洲夏季风降水的集合模拟结果明显优于简单的等权重多模式集合平均结果以及传统空间相关系数加权集合平均结果。鉴于此原因, 本文利用此方法对在A1B (各种能源均衡发展) 排放情景下IPCC-AR4中22个耦合模式所模拟的21世纪各时期亚洲夏季风降水演变趋势进行集合预测。其结果表明: 在A1B排放情景下, 从21世纪中期 (2045～2065年) 开始南亚夏季风降水将比20世纪晚期明显增强; 而东亚夏季风降水相对于20世纪晚期的变化呈现出从南到北经向三极子型异常分布特征, 即华南和华北地区夏季风降水增多, 而长江流域夏季风降水相对于20世纪晚期没有太大变化。并且, 结果还表明亚洲夏季风降水异常这种变化趋势可以延续到21世纪晚期。 相似文献
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June-Yi Lee Bin Wang I.-S. Kang J. Shukla A. Kumar J.-S. Kug J. K. E. Schemm J.-J. Luo T. Yamagata X. Fu O. Alves B. Stern T. Rosati C.-K. Park 《Climate Dynamics》2010,35(2-3):267-283
Given observed initial conditions, how well do coupled atmosphere–ocean models predict precipitation climatology with 1-month lead forecast? And how do the models’ biases in climatology in turn affect prediction of seasonal anomalies? We address these questions based on analysis of 1-month lead retrospective predictions for 21 years of 1981–2001 made by 13 state-of-the-art coupled climate models and their multi-model ensemble (MME). The evaluation of the precipitation climatology is based on a newly designed metrics that consists of the annual mean, the solstitial mode and equinoctial asymmetric mode of the annual cycle, and the rainy season characteristics. We find that the 1-month lead seasonal prediction made by the 13-model ensemble has skills that are much higher than those in individual model ensemble predictions and approached to those in the ERA-40 and NCEP-2 reanalysis in terms of both the precipitation climatology and seasonal anomalies. We also demonstrate that the skill for individual coupled models in predicting seasonal precipitation anomalies is positively correlated with its performances on prediction of the annual mean and annual cycle of precipitation. In addition, the seasonal prediction skill for the tropical SST anomalies, which are the major predictability source of monsoon precipitation in the current coupled models, is closely link to the models’ ability in simulating the SST mean state. Correction of the inherent bias in the mean state is critical for improving the long-lead seasonal prediction. Most individual coupled models reproduce realistically the long-term annual mean precipitation and the first annual cycle (solstitial mode), but they have difficulty in capturing the second annual (equinoctial asymmetric) mode faithfully, especially over the Indian Ocean (IO) and Western North Pacific (WNP) where the seasonal cycle in SST has significant biases. The coupled models replicate the monsoon rain domains very well except in the East Asian subtropical monsoon and the tropical WNP summer monsoon regions. The models also capture the gross features of the seasonal march of the rainy season including onset and withdraw of the Asian–Australian monsoon system over four major sub-domains, but striking deficiencies in the coupled model predictions are observed over the South China Sea and WNP region, where considerable biases exist in both the amplitude and phase of the annual cycle and the summer precipitation amount and its interannual variability are underestimated. 相似文献
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利用1880—2009年海表温度(Sea Surface Temperature, SST)观测资料以及耦合模式比较计划第五阶段(Coupled Model Intercomparison Project phase 5,CMIP5)中4种情景(piControl、historical、RCP2.6、RCP4.5)下的模拟资料,通过资料对比,评估了CMIP5模式对两个最为重要年代际尺度模态——北大西洋年代际振荡(Atlantic Multidecadal Oscillation, AMO)和太平洋年代际振荡(Pacific Decadal Oscillation, PDO)的模拟性能,并分析了在不同增暖情景下,这两个海洋年代际模态的变化特征。结果表明:在historical和piControl情景下,多模式集合可以再现北太平洋、东太平洋和北大西洋海表温度的年代际变化中心,但模拟的AMO和PDO模态的振幅都偏弱,特别是PDO模态在东太平洋强度的再现能力较弱。与观测资料相比,在historical情景下对AMO和PDO时空特征模拟较好的模式有:CESM1-CAM5、FGOALS-g2、GISS-E2-H-CC、MIROC5和NorESM1-ME,多模式集合则有更好的模拟效果。在不同增暖情景下,AMO与PDO的空间特征基本一致且振幅差随增暖变化不明显,但是伴随全球增暖加强,两模态都呈现方差贡献减小的特征,尤其AMO模态。 相似文献
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IPCC AR4中海气耦合模式对中国东部夏季降水及PDO、NAO年代际变化的模拟能力分析 总被引：5，自引：1，他引：4
利用1880—1999年中国东部35站的观测降水资料、英国Hadley中心的海温和海平面气压资料以及IPCC第4次评估报告（AR4）中20世纪气候模拟试验（20C3M）的模式输出结果,对IPCCAR4中22个耦合模式所模拟的我国东部夏季降水的年代际变化情况以及太平洋年代际涛动（PDO）和北大西洋涛动（NAO）的年代际变化情况进行了分析。结果显示,这些模式对20世纪我国东部夏季降水年代际变化的模拟结果并不理想,但对降水在20世纪70年代中期前后的突变具有一定的模拟能力。其中IAP_FGOALSL_0_G可以大致模拟出20世纪70年代中期前后降水型的突变特征,而BCCR_BCM2_0和UKMO_HadGEM1则可以模拟出华北地区降水在20世纪70年代中期之后减少的现象。对于引起我国东部夏季降水年代际变化的重要因子PDO和NAO,模式对它们年代际变化的模拟效果略好于降水。多数模式都可以模拟出PDO和NAO的空间模态,其中CNRM_CM3和UKMO_HadGEM1对PDO年代际变化（8 a以上）的模拟与实际情况比较相似,并可以模拟出20世纪70年代中期之后PDO由负位相转变为正位相的情况,而模式UKMO_HadGEM1也对NAO的年代际变化以及1980年以来不断加强的趋势模拟较好。 相似文献
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The IAP 2-L AGCM is modified by introducing a set of climatological surface albedo data into the model for substituting the model’s original surface albedo parameterization. The comparison between the observations and the simulation results by the modified model shows that the general features of the East Asian summer monsoon can be well reproduced by the modified IAP 2-L AGCM. Especially for the simulation of monsoon precipitation, the modi-fied model can well reproduce not only the monthly mean features of the summer monsoon rainfall over East Asia, but also the stepwise advance and retreat of the East Asian summer monsoon rainbelt. Analysis results demonstrate that the good simulation of the monsoon rainfall is closely related to the reasonable simulation of the large scale gen-eral circulation over East Asian region, such as the western Pacific subtropical high, Asian monsoon low and the low level flows. The good performance of the modified model in the rainfall simulation shows its great potential to serve as a useful tool for the prediction of summer drought / flood events over East Asia. 相似文献