Simulation of the summer circulation over South America by two regional climate models. Part II: A comparison between 1997/1998 El Niño and 1998/1999 La Niña events

Summary This study investigates the capabilities of two regional models (the ICTP RegCM3 and the climate version of the CPTEC Eta model – EtaClim) in simulating the summer quasi-stationary circulations over South America during two extreme cases: the 1997–1998 El Ni?o and 1998–1999 La Ni?a. The results showed that both the models are successful in simulating the interannual variability of summer quasi-stationary circulation over South America. Both the models simulated the intensification of subtropical jet stream during the El Ni?o event, which favoured the blocking of transient systems and increased the precipitation over south Brazil. The models simulated the increase (decrease) of precipitation over north (west) Amazonia during the La Ni?a (El Ni?o) event. The upper level circulation is in agreement with the simulated distribution of precipitation. In general, the results showed that both the models are capable of capturing the main changes of the summer climate over South America during these two extreme cases and consequently they have potential to predict climate anomalies.     

Development of regional future climate change scenarios in South America using the Eta CPTEC/HadCM3 climate change projections: climatology and regional analyses for the Amazon, S?o Francisco and the Paraná River basins

The objective of this study is to assess the climate projections over South America using the Eta-CPTEC regional model driven by four members of an ensemble of the Met Office Hadley Centre Global Coupled climate model HadCM3. The global model ensemble was run over the twenty-first century according to the SRES A1B emissions scenario, but with each member having a different climate sensitivity. The four members selected to drive the Eta-CPTEC model span the sensitivity range in the global model ensemble. The Eta-CPTEC model nested in these lateral boundary conditions was configured with a 40-km grid size and was run over 1961–1990 to represent baseline climate, and 2011–2100 to simulate possible future changes. Results presented here focus on austral summer and winter climate of 2011–2040, 2041–2070 and 2071–2100 periods, for South America and for three major river basins in Brazil. Projections of changes in upper and low-level circulation and the mean sea level pressure (SLP) fields simulate a pattern of weakening of the tropical circulation and strengthening of the subtropical circulation, marked by intensification at the surface of the Chaco Low and the subtropical highs. Strong warming (4–6°C) of continental South America increases the temperature gradient between continental South America and the South Atlantic. This leads to stronger SLP gradients between continent and oceans, and to changes in moisture transport and rainfall. Large rainfall reductions are simulated in Amazonia and Northeast Brazil (reaching up to 40%), and rainfall increases around the northern coast of Peru and Ecuador and in southeastern South America, reaching up to 30% in northern Argentina. All changes are more intense after 2040. The Precipitation–Evaporation (P–E) difference in the A1B downscaled scenario suggest water deficits and river runoff reductions in the eastern Amazon and S?o Francisco Basin, making these regions susceptible to drier conditions and droughts in the future.     

Uncertainty estimation of the global temperature trends for multiple radiosondes, reanalyses, and CMIP3/IPCC climate model simulations

Based on three groups of datasets that include radiosondes, reanalyses, and climate model simulations (e.g., Coupled Model Intercomparison Project, CMIP3) from 1979 to 2008, the interannual variability, global temperature trends, and their uncertainty using ensemble spread among intra-group and inter-group datasets have been discussed. The results show that the interannual temperature variability increased from the troposphere to stratosphere, and the maximum occurs around 50?hPa. The CMIP3 climate models have the largest discrepancy in the stratosphere. The intra-group correlations at 500?hPa generally show high similarity within each data group while the inter-group correlations between reanalyses and the CMIP3 climate model simulations indicate lesser similarity. In contrast, the inter-group correlation at 50?hPa is improved except with the Japanese 25-year Reanalysis Project (JRA-25) dataset, and the Twentieth Century Reanalysis (20CR) reanalysis shows a weak cross correlation. The global temperature trends are highly dependent on the individual data sources. Compared to the radiosondes, the reanalyses show a large ensemble spread of trends in the stratosphere, and the CMIP3 climate model simulations have a large ensemble spread in the height of the crossover point where tropospheric warming changes into stratospheric cooling. The largest ensemble spread among the reanalyses in the stratosphere is mainly from the large discrepancy in the JRA-25 reanalysis after 1998 and a relatively weak anomaly in the 20CR before 1986. The largest ensemble spread among the CMIP3 climate models in the troposphere is related to the influence of both volcanic eruptions and El Ni?o/La Ni?a–Southern Oscillation events. The strong anomalies corresponding to the volcanic eruptions of El Chichon in 1982 and Mt Pinatubo in 1991 are clearly identified in the stratosphere. These volcanic eruptions reduced the warming in the troposphere and strengthened the cooling in the stratosphere during the most recent 30?years.     

Asymmetry of Atmospheric Responses to Two-Type El Ni?o and La Ni?a over Northwest Pacific

The mechanism for asymmetric atmospheric responses to the central Pacific(CP) El Ni?o and La Ni?a over the western North Pacific(WNP) is studied in this paper. The negative anomalies of rainfall over the key region of WNP are explained by diagnosing the column-integrated equations of moisture and moist static energy(MSE). It is revealed that the nonlinear advection of moist enthalpy is critical to introduce negative rainfall anomalies over the region. The anomalous easterly(westerly) in La Ni?a(CP El Ni?o) causes negative advection of anomalous moist enthalpy, inducing negative heating anomaly and an anticyclone anomaly in the WNP, which weakens(strengthens) the cyclone(anticyclone) in La Ni?a(CP El Ni?o). The MSE budget analysis shows a larger nonlinear term in CP El Ni?o than in eastern Pacific(EP) El Ni?o, inconsistent with the amplitudes of sea surface temperature anomalies. The reason is that the nonlinear term transforms to positive above 700 h Pa in EP El Ni?o, offsetting the negative advection below 700 h Pa and thus making the nonlinear term smaller. The nonlinear term is negative at low levels in CP El Ni?o, resulting in a larger nonlinear term. The stronger precipitation anomalies in the WNP during EP El Ni?o can be attributed to the linear moist enthalpy advection. The mean easterly wind at mid levels causes a larger(smaller) positive moist enthalpy advection in CP(EP) El Ni?o, due to a larger(smaller) moist enthalpy gradient, resulting in a positive(negative) linear moist enthalpy advection, which weakens(strengthens) the negative precipitation anomalies in the key region.     

NUIST地球系统模式模拟ENSO对西北太平洋热带气旋活动的影响

地球系统模式已经逐步成为研究热带气旋(TC)活动气候变化的重要工具之一,之前的研究发现南京信息工程大学地球系统模式(NESM)高分辨率版本可以较好地模拟全球海温分布及TC活动的气候特征.本研究进一步分析了NESM地球系统模式模拟西北太平洋TC活动的年际变化,并与1967～2016年观测的TC活动进行对比.NESM模式高...     

Influence of Intraseasonal Oscillation on the Asymmetric Decays of El Ni?o and La Ni?a

Warm and cold phases of El Nino–Southern Oscillation (ENSO) exhibit a significant asymmetry in their decay speed. To explore the physical mechanism responsible for this asymmetric decay speed, the asymmetric features of anomalous sea surface temperature (SST) and atmospheric circulation over the tropical Western Pacific (WP) in El Nino and La Nina mature-to-decay phases are analyzed. It is found that the interannual standard deviations of outgoing longwave radiation and 850 hPa zonal wind anomalies over the equatorial WP during El Nino (La Nina) mature-to-decay phases are much stronger (weaker) than the intraseasonal standard deviations. It seems that the weakened (enhanced) intraseasonal oscillation during El Nino (La Nina) tends to favor a stronger (weaker) interannual variation of the atmospheric wind, resulting in asymmetric equatorial WP zonal wind anomalies in El Nino and La Nina decay phases. Numerical experiments demonstrate that such asymmetric zonal wind stress anomalies during El Nino and La Nina decay phases can lead to an asymmetric decay speed of SST anomalies in the central-eastern equatorial Pacific through stimulating di erent equatorial Kelvin waves. The largest negative anomaly over the Nino3 region caused by the zonal wind stress anomalies during El Nino can be threefold greater than the positive Nino3 SSTA anomalies during La Nina, indicating that the stronger zonal wind stress anomalies over the equatorial WP play an important role in the faster decay speed during El Nino.     

ENSO对中国冬半年降水影响的不对称性及机制分析

利用1979—2010年观测和再分析资料,诊断分析ENSO对中国华南冬半年降水的影响及其机制。结果表明,在El Ni?o冬半年期间,东亚沿岸上空对流层低层南风的增强导致了水汽输送明显偏多,水汽在华南辐合,使得大气可降水量和比湿增加,降水显著偏多。而在La Ni?a冬半年期间,这些大气要素并没有呈现显著的相反变化,负异常的量值很弱并在统计上不显著。通过进一步分析El Ni?o和La Ni?a冬半年期间季节内振荡的特点,给出一种华南冬半年降水对ENSO信号不对称响应的物理解释。El Ni?o期间,热带西太平洋到南海地区的季节内振荡不活跃,与El Ni?o相联系的西北太平洋反气旋性环流异常造成的水汽输送以及水汽辐合在华南能够稳定维持,致使华南降水明显偏多。但在La Ni?a冬半年期间,季节内振荡很活跃,与La Ni?a相联系的西北太平洋气旋性环流异常受到季节内时间尺度的扰动影响,ENSO的年际变化信号被季节内振荡破坏,使得西北太平洋和华南的年际异常信号不能得到稳定维持,导致与ENSO信号相联系的年际变化在统计上不显著。因此,热带西太平洋到南海地区的季节内振荡强度在El Ni?o和La Ni?a冬半年期间的差异,是华南冬半年降水对ENSO信号不对称响应的一个主要原因。      

The internal climate variability of HadCM3, a version of the Hadley Centre coupled model without flux adjustments

We examine the internal climate variability of a 1000?year long integration of the third version of the Hadley Centre coupled model (HadCM3). The model requires no flux adjustment, needs no spin up procedure prior to coupling and has a stable climate in the global mean. The principal aims are (1) to validate the internal climate variability against observed climate variability, (2) to examine the model for any periodic modes of variability, (3) to use the model estimate of internal climate variability to asses the probability of occurrence of observed trends in climate variables, and (4) to compare HadCM3 with the previous version of the Hadley Centre model, HadCM2. The magnitude and frequency characteristics of the variability of the global mean surface temperature of HadCM3 on annual to decadal time scales is in good agreement with the observations. Observed upward trends in temperature over the last 20?years and longer are inconsistent with the internal variability of the model. The simulated spatial pattern of surface temperature variability is qualitatively similar to that observed, although there is an overestimation of the land temperature variability and regional errors in ocean temperature variability. The model simulates an El Niño Southern Oscillation with an irregular 3–4?year cycle, and with a teleconnection pattern which is much more like the observations than was found in HadCM2. The interdecadal variability of the model ocean in the tropical Pacific, North Pacific and North Atlantic is broadly similar to that in the real world with none of the simulated patterns having any periodic behaviour. HadCM3 simulates an Arctic Oscillation/North Atlantic Oscillation (NAO) in Northern Hemisphere winter which has a spatial pattern consistent with the observations in the Atlantic region, but has too much teleconnection with the North Pacific. The recent observed upward trend in the NAO index is inconsistent with the model internal variability. The variability of the simulated zonal mean atmospheric temperature shows some marked differences to the observed zonal mean temperature variability, although the comparison is confounded by the sparse observational network and its possible contamination by a climate change signal.     

ENSO regulation of MJO teleconnection

The extratropical teleconnections associated with Madden?CJulian Oscillation (MJO) are shown to have an action center in the North Pacific where the pressure anomalies have opposite polarities between the Phase 3 (convective Indian Ocean) and Phase 7 (convective western Pacific) of the MJO. The teleconnection in the same phase of MJO may induce opposite anomalies over East Asia and North America between El Ni?o and La Ni?a years. During MJO Phase 3, a gigantic North Pacific anticyclonic anomaly occurs during La Ni?a, making coastal northeast Asia warmer/wetter than normal, but the west US colder/drier; whereas during El Ni?o the anticyclonic anomaly is confined to the central North Pacific, hence the northwest US experiences warmer than normal weather under influence of a downstream cyclonic anomaly. During Phase 7, an extratropical cyclonic anomaly forms over the northwest Pacific during La Ni?a due to convective enhancement over the Philippine Sea, causing bitter winter monsoon over Japan; whereas during El Ni?o, the corresponding cyclonic anomaly shifts to the northeast Pacific due to enhanced convection over the equatorial central Pacific, which causes warm and wet conditions along the west coast of US and Canada. Further, the presence of ENSO-induced seasonal anomalies can significantly modify MJO teleconnection, but the aforementioned MJO teleconnection can still be well identified. During Phase 3, the MJO teleconnection pattern over North Pacific will be counterbalanced (enhanced) by El Ni?o (La Ni?a)-induced seasonal mean anomalies. During Phase 7, on the other hand, the MJO teleconnection anomalies in the northeastern Pacific will be enhanced during El Ni?o but reduced during La Ni?a; thereby the impacts of MJO teleconnection on the North America is expected to be stronger during El Ni?o than during La Ni?a.     

厄尔尼诺次年夏季中国地区云的变化特征及其与降水的关系

基于1961—2010年中国地面台站和卫星观测等多种数据,对不同类型厄尔尼诺事件次年夏季中国地区云的变化特征和不同类型降水的变化特征进行了分析,探讨云的变化特征与总降水异常的复杂联系。结果表明:站点数据中,厄尔尼诺事件次年夏季总云量和低云量的异常与降水异常分布形势大致相同;积雨云、雨层云和层积云等低云的出现频率有所增加。云量与降水异常在全国范围内表现出显著的正相关;通过显著性检验的正相关站点,云量与降水异常的线性关系也通过了显著性检验,总云量和低云量与降水的增加比例分别接近1:3和1:1。卫星观测数据中,厄尔尼诺事件次年夏季高云量、深对流云量、光学厚度和云水路径的变化与站点降水异常基本呈正相关;黄河以南地区总降水的变化主要来源于对流降水的异常,其贡献比例高达80%。中国东部地区低云对降水具有很好的指示作用;厄尔尼诺事件次年夏季南方地区总降水的异常主要来自对流降水的变化;对流降水异常增加与深对流云的异常增多有关。厄尔尼诺事件的发生使得次年夏季中国季风区对流活动增强,对流云云量增多,云层增厚,云顶向上发展,故而对流降水增加,异常雨带形成。      

ENSO与中国夏季降水的联系:冬季QBO的调制作用

使用NCEP/NCAR再分析资料、中国气象局台站降水资料和GPCC降水资料,系统研究了在冬季平流层准两年振荡(Quasi-Biennial Oscillation, QBO)调制下,厄尔尼诺-南方涛动(El Ni?o-Southern Oscillation, ENSO)不同阶段与中国夏季降水的可能联系。根据两者的位相和强度,可将它们的配置分为QBO西风/El Ni?o、QBO西风/La Ni?a、QBO东风/El Ni?o、QBO东风/La Ni?a。研究结果表明,在年际时间尺度上,ENSO和QBO无显著相关关系。冬季QBO西风位相时,El Ni?o发展年夏季,我国整体偏旱,而华南偏涝;衰减年夏季,华南、华东北部偏旱,东北、长江流域偏涝。La Ni?a发展年夏季,我国东部降水异常呈负-正-负的三极分布;衰减年夏季,东南沿海偏涝。冬季QBO东风位相时,El Ni?o发展年夏季,长江以北偏旱;衰减年夏季,我国东部降水异常呈负-正-负的三极分布。La Ni?a发展年夏季,江淮和华南南部偏旱;衰减年夏季,我国东部沿海偏涝。ENSO是影响我国夏季降水异常的重要因子,而QBO的调制作用在ENSO衰减年夏季更为显著。相比冬季QBO东(西)风位相,QBO西(东)风位相时El Ni?o (La Ni?a)期间赤道西太平洋负(正)海温异常更强,衰减年夏季位于西太平洋的异常下沉(上升)运动和印度洋的异常上升(下沉)运动更强更深厚,西太平洋副热带高压范围更大(小),南亚高压更偏东(西)。      

国家气候中心两个CMIP6模式模拟的东亚夏季风的季节内演变

分析了国家气候中心两个参加第六次国际耦合模式比较计划（CMIP6）的模式BCC-CSM2-MR和BCC-ESM1对东亚夏季风季节内演变的模拟情况,包括气候态特征以及在ENSO（El Ni?o and Southern Oscillation）循环不同位相下的特征。本文同时对比分析了观测海温海冰驱动大气环流模式试验（AMIP试验）以及耦合模式的历史气候模拟试验（Historical试验）的结果。结果表明,模式能够合理地模拟出东亚夏季风环流和降水的气候态特征。相比大气模式,耦合模式能够明显改善对气候态的模拟,特别是耦合模式能够较好地模拟出副热带高压从6～8月向北以及向东移动的季节内演变特征。对于El Ni?o衰减年和La Ni?a年合成来说,大气模式能够在一定程度上模拟出El Ni?o衰减年（La Ni?a年）副高偏西（东）、对流减弱（增强）的特征,但是对于位置和强度的模拟存在偏差,特别是对于其季节内尺度的演变。耦合模式相比大气模式来说,并没有改善对于ENSO循环影响东亚夏季风季节内演变的模拟,这可能和耦合模式模拟的ENSO本身的偏差有关。因此要想改善对于东亚夏季风季节内演变及其年际差异的模拟,除了考虑海气相互作用之外,还需要改进模式对于ENSO的模拟效果。     

厄尔尼诺/拉尼娜与重庆次年夏季涝/旱的非对称关系

本文详细分析了厄尔尼诺/拉尼娜与重庆夏季典型涝/旱年之间的不对称关系。结果表明:(1)厄尔尼诺和拉尼娜对重庆次年夏季降水有不对称影响。厄尔尼诺年的大气环流异常与重庆夏季典型涝年的特征一致;然而,拉尼娜年的大气环流异常与重庆夏季典型旱年的特征不一致。(2)从冬季到次年夏季,厄尔尼诺对重庆夏季典型涝年的影响主要是通过热带印度洋海温的‘接力效应’维持的。     

Impact of Earth’s orbit and freshwater fluxes on Holocene climate mean seasonal cycle and ENSO characteristics

We use a state-of-the-art 3-dimensional coupled model to investigate the relative impact of long term variations in the Holocene insolation forcing and of a freshwater release in the North Atlantic. We show that insolation has a greater effect on seasonality and La Ni?a events and is the major driver of sea surface temperature changes. In contrast, the variations in precipitation reflect changes in El Ni?o events. The impact of ice-sheet melting may have offset the impact of insolation on El Ni?o Southern Oscillation variability at the beginning of the Holocene. These simulations provide a coherent framework to refine the interpretation of proxy data and show that changes in seasonality may bias the projection of relationships established between proxy indicators and climate variations in the east Pacific from present day records.     

海温异常对东亚夏季风影响机理的研究进展

从短期气候预测关注的外强迫信号角度出发,回顾了国内外在海温异常对东亚夏季风和我国汛期降水影响机理方面的主要研究进展,重点评述了热带太平洋ENSO循环、热带印度洋全区一致型海温模态、热带印度洋海温异常偶极子、南印度洋偶极子和北大西洋海温三极子模态的年际变化及其对东亚夏季风年际变率的影响。从研究成果在短期气候预测业务中应用的角度,重点关注海温异常和东亚夏季风年际变率以及我国汛期降水多雨带位置的关系,总结了海温异常作为外强迫信号对我国汛期降水预测的指示意义以及汛期降水预测的难度。最后指出气候预测业务对东亚夏季风影响的机理研究和动力气候模式发展方面的需求。     

Responses of Cloud-Radiative Forcing to Strong El Ni?o Events over the Western Pacific Warm Pool as Simulated by CAMS-CSM

Cloud-radiative forcing(CRF) at the top of the atmosphere(TOA) over the western Pacific warm pool(WP) shows unique characteristics in response to El Ni?o events. In this region, the responses of CRF to El Ni?o events have been a useful metric for evaluating climate models. Satellite data are used to analyze the CRF anomalies to El Ni?o events simulated by the new and old versions of the Climate System Model of the Chinese Academy of Meteorological Sciences(CAMS-CSM), which has participated in the Atmospheric Model Intercomparison Project(AMIP). Here, simulations for super El Ni?o years, El Ni?o years, and normal years are compared with observations. The results show that the mean values of both longwave CRF(LWCRF) and shortwave CRF(SWCRF) in CAMS-CSM are weaker than the observations for each category of El Ni?o events. Compared with the old version of CAMS-CSM, the decrease in LWCRF during El Ni?o events is well simulated by the new version of CAMS-CSM. However, both new and old models cannot reproduce the anomalous SWCRF in El Ni?o events. The biases in the CRF response to El Ni?o events are attributed to the biases in the cloud vertical structure because of a weaker crash of the Walker circulation in CAMS-CSM. Due to the modification of the conversion rate from cloud droplets to raindrops in the cumulus convection scheme, the new version of CAMS-CSM has better CRF skills in normal years, but biases in El Ni?o events still exist in the new version. Improving the response of the Walker circulation to El Ni?o events is key to higher skills in simulating the cloud radiative responses.     

Climate downscaling over South America for 1961–1970 using the Eta Model

This study shows the results from a regional climate simulation of the present-day climate, corresponding to the period 1961–1970 over South America, using the regional Eta Model nested within the HadAM3P model from the UK Hadley Centre. The simulation analysis is focused on assessing the capability of the nested regional model in representing spatial patterns of seasonal mean climate and the annual cycle of precipitation and temperature. The goals of this 10-year run for South America are to verify if the Eta Model can be used in climate-change scenarios and to verify if this model has the ability to generate added value for the South American continent. The Eta Model was chosen because there are few investigations using the Eta Model for long integrations over South America and because the vertical coordinate system used in this model is recommended for use over South America due to the presence of the Andes range. In the present 10-year simulation, the regional model reproduced many of the South American mesoscale climate features and together added new value to the driver model. Value was also added to the driver model by reducing seasonal biases in austral winter relative to austral summer. The regional model also exhibits better performance in the representation of low-level circulation, such as the topographically induced northwesterly flux.     

The relative importance of ENSO and tropical Atlantic sea surface temperature anomalies for seasonal precipitation over South America: a numerical study

The role of tropical Atlantic sea surface temperature (SST) anomalies during ENSO episodes over northeast Brazil (Nordeste) is investigated using the CPTEC/COLA Atmospheric General Circulation Model (AGCM). Four sets of integrations are performed using SST in El Niño and La Niña (ENSO) episodes, changing the SST of the Atlantic Ocean. A positive dipole (SST higher than normal in the tropical North Atlantic and below normal in the tropical South Atlantic) and a negative dipole (opposite conditions), are set as the boundary conditions of SST in the Atlantic Ocean. The four experiments are performed using El Niño or La Niña SST in all oceans, except in the tropical Atlantic where the two phases of the SST dipole are applied. Five initial conditions were integrated in each case in order to obtain four ensemble results. The positive SST dipole over the tropical Atlantic Ocean and El Niño conditions over the Pacific Ocean resulted in dry conditions over the Nordeste. When the negative dipole and El Niño conditions over the Pacific Ocean were applied, the results showed precipitation above normal over the north of Nordeste. When La Niña conditions over Pacific Ocean were tested together with a negative dipole, positive precipitation anomalies occurred over the whole Nordeste. Using the positive dipole over the tropical Atlantic, the precipitation over Nordeste was below average. During La Niña episodes, the Atlantic Ocean conditions have a larger effect on the precipitation of Nordeste than the Pacific Ocean. In El Niño conditions, only the north region of Nordeste is affected by the Atlantic SST. Other tropical areas of South America show a change only in the intensity of anomalies. Central and southeast regions of South America are affected by the Atlantic conditions only during La Niña conditions, whereas during El Niño these regions are influenced only by conditions in the Pacific Ocean.     

Causes and Predictability of the 2021 Spring Southwestern China Severe Drought

In the spring of 2021, southwestern China (SWC) experienced extreme drought, accompanied by the highest seasonal-mean temperature record since 1961. This drought event occurred in the decaying phase of a La Ni?a event with negative geopotential height anomalies over the Philippine Sea, which is distinct from the historical perspective. Historically, spring drought over SWC is often linked to El Ni?o and strong western North Pacific subtropical high. Here, we show that the extreme drought in the spring of 2021 may be mainly driven by the atmospheric internal variability and amplified by the warming trend. Specifically, the evaporation increase due to the high temperature accounts for about 30% of drought severity, with the contributions of its linear trend portion being nearly 20% and the interannual variability portion being about 10%. Since the sea surface temperature forcing from the tropical central and eastern Pacific played a minor role in the occurrence of drought, it is a challenge for a climate model to capture the 2021 SWC drought beyond one-month lead times.     

CMIP5多模式模拟两类El Ni(n)o海表盐度分布及与降水的关系

利用CMIP5提供的25个工业革命前控制试验(piControl)模拟数据评估了热带太平洋两类El Ni(n)o(即东部EP和中部CP型El Ni(n)o)的海表盐度(SSS)空间结构差异及其与海表温度(SST)和降水的关系.结果表明:(1)大部分模式能够模拟出EP和CP型空间结构,两类El Ni(n)o中的SST、降水和SSS的空间技巧评分依次减小,其中,EP型SST和降水水平分布的模拟能力强于CP型,SSS则为CP型强于EP型,CP型模拟的SST、SSS和降水异常中心位置较EP型偏西且强度偏弱;(2) CP型SST、降水和SSS三者空间分布的线性一致性比EP型好,即在CP型中,SST影响降水,进而影响SSS,同时SSS对SST调制的反馈机制较显著,而对于EP型,由于海洋水平平流和非局地效应等因素,使得SST与SSS空间对应较差;(3)依据多模式模拟的SSS空间技巧评分高低将CMIP5模式分为两类,技巧评分低(高)的模式模拟的SST、SSS和降水异常值的中心位置偏西(偏东),引起中心位置偏移的原因与模式模拟赤道太平洋冷舌的位置有关,即赤道太平洋冷舌西伸显著,导致发生El Ni(n)o时SST异常变暖西伸显著,进而使得降水异常和SSS异常位置偏西.同时,技巧评分低的模式还易出现向东南延伸的负SSS异常,原因是双赤道辐合带的东南分支过于明显,即降水偏多,导致SSS偏淡.SSS变化会影响ENSO的发生发展.因此,探讨两类El Ni(n)o盐度分布的差异及相关物理场的关系,为提高模式的气候模拟和预测提供有益的借鉴.