印度洋dipole事件的年际变化与ENSO事件的联系

通过对nino3指数和DMI序列的分析，发现两种物理现象都有4a左右的主要周期，而且印度洋偶极子事件还存在有2a左右的振荡周期，而厄尔尼诺事件在2a时间尺度上周期性不明显；对nino3指数和DMI进行年际时间尺度滤波，结果表明，在年际时间尺度上，两者的相关性比未滤波时有了一定的提高；对年际滤波之后的偶极子事件和ELNINO事件的相关分析可以发现，ELNINO对于印度洋偶极子事件的影响要大于IOD对于太平洋ENSO事件，显示了两者物理现象的影响不对称。     

Relationships of interannual variability between the equatorial pacific and tropical Indian Ocean in 17 CMIP5 models

Seventeen coupled general circulation models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) are employed to assess the relationships of interannual variations of sea surface temperature (SST) between the tropical Pacific (TP) and tropical Indian Ocean (TIO). The eastern/central equatorial Pacific features the strongest SST interannual variability in the models except for the model CSIRO-Mk3-6-0, and the simulated maximum and minimum are produced by models GFDL-ESM2M and GISS-E2-H respectively. However, It remains a challenge for these models to simulate the correct climate mean SST with the warm pool-cold tongue structure in the equatorial Pacific. Almost all models reproduce El Niño-Southern Oscillation (ENSO), Indian Ocean Dipole mode (IOD) and Indian Ocean Basin-wide mode (IOB) together with their seasonal phase lock features being simulated; but the relationship between the ENSO and IOD is different for different models. Consistent with the observation, an Indian Ocean basin-wide warming (cooling) takes place over the tropical Indian Ocean in the spring following an El Niño (La Niña) in almost all the models. In some models (e.g., GFDL-ESM2G and MIROC5), positive ENSO and IOB events are stronger than the negative events as shown in the observation. However, this asymmetry is reversed in some other models (e.g., HadGEM2-CC and HadGEM2-ES).     

Interannual variations of surface winds over China marginal seas

In a study of surface monsoon winds over the China marginal seas, Sun et al. (2012) use singular value decomposition method to identify regional dominant modes and analyze their interdecadal variability. This paper continues to evaluate the interannual variability of each dominant mode and its relation to various atmospheric, oceanic and land factors. The findings include: 1) The intensity of the winter monsoon over the East China Sea is highly correlated with the Siberian High intensity and anti-correlated with the latitudinal position of the Aleutian Low as well as the rainfall in eastern China, Korean Peninsula and Japan; 2) The western Pacific subtropical high is significantly correlated with the summer monsoon intensity over the East China Sea and anti-correlated with the summer monsoon over the South China Sea; 3) The winter monsoon in a broad zonal belt through the Luzon Strait is dominated by the ENSO signal, strengthening in the La Ni a phase and weakening in the El Ni o phase. This inverse relation exhibits interdecadal shift with a period of weak correlation in the 1980s; 4) Analysis of tidal records validates the interdecadal weakening of the East Asian summer monsoon and reveals an atmospheric bridge that conveys the ENSO signal into the South China Sea via the winter monsoon.     

Modulation of tropical cyclogenesis over the South China Sea by ENSO Modoki during boreal summer

This study examines the modulation of tropical cyclogenesis over the South China Sea(SCS) by the El Nio-Southern Oscillation(ENSO) Modoki during the boreal summer. Results reveal that there were more tropical cyclones(TCs) formed over the SCS during central Pacific warming years and less TC frequency during central Pacific cooling years. How different environmental factors(including low-level relative vorticity, mid-level relative humidity, vertical wind shear, and potential intensity) contribute to this influence is investigated, using a genesis potential(GP) index developed by Emanuel and Nolan. Composite anomalies of the GP index are produced for central Pacific warming and cooling years separately, which could account for the changes of TC frequency over the SCS in different ENSO Modoki phases. The degree of contribution by each factor is determined quantitatively by producing composites of modified indices in which only one of the contributing factors varies, with the others set to climatology. The results suggest that the vertical wind shear and low-level relative vorticity, which are associated with the ENSO Modoki-induced anomalous circulations in Matsuno-Gill patterns, make the largest contributions to the ENSO Modoki modulation of tropical cyclogenesis over the SCS as implied by the GP index. These results highlight the important roles of dynamic factors in the modulation of TC frequency over the SCS by the ENSO Modoki during the boreal summer.     

Annual and interannual variability of scatterometer ocean surface wind over the South China Sea

To investigate the annual and interannual variability of ocean surface wind over the South China Sea (SCS), the vector empirical orthogonal function (VEOF) method and the Hilbert-Huang transform (HHT) method were employed to analyze a set of combined satellite scatterometer wind data during the period from December 1992 to October 2009. The merged wind data were generated from European Remote Sensing Satellite (ERS)-1/2 Scatterometer, NASA Scatterometer (NSCAT) and NASA’s Quick Scatterometer (QuikSCAT) wind products. The first VEOF mode corresponds to a winter-summer mode which accounts for 87.3% of the total variance and represents the East Asian monsoon features. The second mode of VEOF corresponds to a spring-autumn oscillation which accounts for 8.3% of the total variance. To analyze the interannual variability, the annual signal was removed from the wind data set and the VEOFs of the residuals were calculated. The temporal mode of the first interannual VEOF is correlated with the Southern Oscillation Index (SOI) with a four-month lag. The second temporal interannual VEOF mode is correlated with the SOI with no time lag. The time series of the two interannual VEOFs were decomposed using the HHT method and the results also show a correlation between the interannual variability and El Niño-Southern Oscillation (ENSO) events.     

NUMERICAL SIMULATION OF INTERANNUAL AND INTERDECADAL VARIABILITY OF SURFACE WIND OVER THE TROPICAL PACIFIC

A global atmospheric general circulation model (L9R15 AGCMs) forced by COADS SST was integrated from 1945 to 1993. Interannual and interdecadal variability of the simulated surface wind over the tropical Pacific was analyzed and shown to agree vey well with observation. Simulation of surface wind over the central-western equatorial Pacific was more successful than that over the eastern Pacific. Zonal propagating feature of interannual variability of the tropical Pacific wind anomalies and its decadal difference were also simulated successfully. The close agreement between simulation and observation on the existence of obvious interdecadal variability of tropical Pacific surface wind attested to the high simulation capability of AGCM.     

The interannual and decadal variability of the sea level in the Japan/East Sea

Sea level observed by altimeter during the 1993–2007 period and the thermosteric sea level from 1945 through 2005 obtained by using the global ocean temperature data sets recently published are used to investigate the interannual and decadal variability of the sea level in the Japan/East Sea (JES) and its response to El Niño and Southern Oscillation (ENSO). Both the interannual variations of the sea level observed by altimeter and those of the thermosteric sea level obtained from reanalyzed data in the JES are closely related to ENSO. As a result, one important consequence is that the sea level trends are mainly caused by the thermal expansion in the JES. An ‘enigma’ is revealed that the correlation between the thermosteric sea level and ENSO during the PDO (Pacific Decadal Oscillation) warm phase (post mid-1970s) is inconsistent with that during the cold phase (pre mid-1970s) in the JES. The thermosteric sea level trends and the Southern Oscillation Index (SOI) suggest a strong negative correlation during the period 1977–1998, whereas there appears a relatively weak positive correlation during the period 1945–1976 in the JES. Based on the SODA (Simple Oceanographic Data Assimilation) datasets, possible mechanisms of the interannual and decadal variability of the sea level in the JES are discussed. Comprehensive analysis reveals that the negative anomalies of SOI correspond to the positive anomalies of the southeast wind stress, the net advective heat flux and the sea level in the JES during the PDO warm phase. During the PDO cold phase, the negative anomalies of SOI correspond to the positive anomalies of the southwest wind stress, the negative anomalies of the net advective heat flux and the sea level in the JES.     

Characteristics of change of the SST in the tropical western Pacific and the tropical Indian Ocean and its response to the change of the Antarctic ice area

In this paper, by using ocean surface temperature data (COADS), the study is made of the characteristics of the monthly and annual changes of the SST in the tropical western Pacific and Indian Oceans, which have important influences on the climate change of the whole globe and the relation between ENSO(E1 Nino-Southern Oscillation) and the Antarctic ice area is also discussed. The result indicates that in the tropical western Pacific and the Indian Oceans the change of Sea Surface Temperture (SST) is conspicuous both monthly and armaully, and shows different change tendency between them. This result may be due to different relation in the vibration period of SST between the two Oceans. The better corresponding relationship is obvious in the annual change of SST in the tropical Indian Ocean with the occurrence El Nino and LaNlra. The change of the SST in the tropical western Pacific and the tropical Indian Oceans has a close relation to the Antarctic ice area, especially to the ice areas in the eastern-south Pole and Ross Sea, and its notable correlative relationship appears in 16 months when the SST of the tropical western Pacific and the Indian Oceans lag back the Antarctic ice area.     

Interannual variability of SST,SLA and wind waves in the Hawaii area and their responses to ENSO

Time series of sea surface temperature (SST),wind speed and significant wave height (SWH) from meteorologicalbuoys of the National Data Buoy Center (NDBC) are useful for studying the interannual variability and trend of these quantities at the buoy areas.The measurements from 4 buoys (B51001,B51002,B51003 and B51004) in the Hawaii area are used to study theresponses of the quantities to EI Nino and Southern Oscillation (ENSO).Long-term averages of these data reflect precise seasonaland climatological characteristics of SST,wind speed and SWH around the Hawaii area.Buoy observations from B51001 suggest asignificant warming trend which is,however,not very clear from the other three buoys.Compared with the variability of SST andSWH,the wind speeds from the buoy observations show an increasing trend.The impacts of El Nifio on SST and wind waves arealso shown.Sea level data observed by altimeter during October 1992 to September 2006 are analyzed to investigate the variabilityof sea level in the Hawaii area.The results also show an increasing trend in sea level anomaly (SLA).The low-passed SLA in theHawaii area is consistent with the inverse phase of the low-passed Sol (Southern Oscillation Index).Compared with the low-passedSOl and PDO (Pacific Decadal Oscillation),the low-passed PNA (Pacific-North America Index) has a better correlation with thelow-passed SLA in the Hawaii area.     

冬夏季热带太平洋至印度洋次表层海温变化的模态特征

采用美国Scripps海洋研究所的1955—1998年全球海洋上层海水温度月距平资料,对热带太平洋至印度洋各层海温进行经验正交函数分解,分析其主要模态特征。结果表明：热带太平洋至印度洋次表层海温场主要表现出东、西太平洋海温异常反位相变化的特征,异常强度冬季明显强于夏季。冬季赤道东太平洋40m层,东印度洋至西太平洋120m层,夏季赤道东太平洋40m层,东印度洋至西太平洋160m层为海温异常的显著区域。冬季0—60m层第一特征向量表现出厄尔尼诺（拉尼娜）模态特征,第二特征向量表现出海温异常的东西运移模态特征,80—400m层第一特征向量表现出西太平洋暖池模态特征,第二特征向量表现出海温异常的东西运移模态特征。夏季0—60m层特征向量表现出厄尔尼诺（拉尼娜）模态,80—400m层特征向量表现出西太平洋暖池模态特征。     

热带次表层海温对中国东部夏季气候的影响

热带海洋热状况是影响中国气候变化的主要因子之一,为了研究热带次表层海温如何影响中国气候,通过相关计算和合成分析等方法讨论了热带太平洋至印度洋次表层海温异常对中国东部夏季降水和温度的影响。结果表明:当冬季赤道东印度洋至西太平洋次表层海温偏暖(偏冷),中印度洋和东太平洋次表层海温偏冷(偏暖),夏季,长江中下游地区降水偏少(偏多),华南、华北和东北大部地区降水偏多(偏少);中国东部大范围高温(低温)。其可能的影响途径为,东亚夏季风环流对热带次表层海温异常的响应导致了其年际变化,进而引起中国东部夏季气候的异常分布。     

An ice-ocean model study to explore climate change mechanisms in comparison with interannual-to-decadal variability of geochemical tracers

One way to identify the mechanisms that are crucial to Arctic climate change is to use existing data that exhibit interannual-to-decadal variability in the sea ice and ocean interior due to atmospheric forcing. Since around 1960 s, valuable geochemical data of the ocean interior, together with atmospheric and sea ice data, have been analyzed and examined in a coupled ice–ocean model with an idealized configuration of the Arctic Basin. This is fundamentally driven by negative salt flux, in addition to atmospheric circulation and cooling. This strategy has a clear advantage over more sophisticated models with higher resolution that require extensive data collections for verification. Around 1990, the dominant atmospheric mode shifted from the Northern Annular Mode(NAM) to the Arctic Dipole Mode(ADM). The variability of sea ice cover was explained by these two modes sequentially and reproduced in the model. In particular, the geochemical fields indicated a movement of the Transpolar Drift Stream due to the NAM and an oscillation of the Pacific water between the Atlantic and Pacific sides due to the ADM. Both these features were reproduced reasonably well by the oceanic tracers in the model, including the time lags of about one third of the oscillation periods. Thus, this strategy can suggest methods and locations for monitoring oceanographic responses to Arctic climate change.     

Seasonal variability of zonal heat advection in the mixed layer of the tropical Pacific

Zonal heat advection （ZHA） plays an important role in the variability of the thermal structure in the tropical Pacific Ocean, especially in the western Pacific warm pool （WPWP）. Using the Simple Ocean Data Assimilation （SODA） Version 2.02/4 for the period 1958-2007, this paper presents a detailed analysis of the climatological and seasonal ZHA in the tropical Pacific Ocean. Climatologically, ZHA shows a zonal- band spatial pattern associated with equatorial currents and contributes to forming the irregular eastern boundary of the WPWP （EBWP）. Seasonal variation of ZHA with a positive peak from February to July is most prominent in the Nifio3.4 region, where the EBWP is located. The physical mechanism of the seasonal cycle in this region is examined. The mean advection of anomalous temperature, anomalous advection of mean temperature and eddy advection account for 31%, 51%, and 18% of the total seasonal variations, respectively. This suggests that seasonal changes of the South Equatorial Current induced by variability of the trade winds are the dominant contributor to the anomalous advection of mean temperature and hence, the seasonality of ZHA. Heat budget analysis shows that ZHA and surface heat flux make comparable contributions to the seasonal heat variation in the Nifio3.4 region, and that ZHA cools the upper ocean throughout the calendar year except in late boreal spring. The connection between ZHA and EBWP is further explored and a statistical relationship between EBWP, ZHA and surface heat flux is established based on least squares fitting.     

Anomalies of asian summer monsoon related to ssta in the south China Sea and the tropical pacific

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全球海洋初级生产力时空异常变化对ENSO事件的响应

海洋初级生产力在海洋环境要素的驱动下,在不同海域呈现出不同的时空变化特征,这种时空演变特征在不同的ENSO事件类型下差异更为显著。本文基于1998年1月至2017年12月全球海洋初级生产力的卫星遥感数据集,通过改进海洋时空双约束聚类挖掘方法,挖掘了近20年海洋初级生产力的时空聚簇模式,并从时空分布和空间移动2个方面对比分析了海洋初级生产力时空演变簇与ENSO（El Niño-Southern Oscillation）事件之间的关系。结果表明：① 在EP（Eastern-Pacific）型El Niño事件期间,海洋初级生产力异常低值时空簇主要分布在赤道太平洋东部或中东部海域,异常高值时空簇主要分布在西太平洋和南太平洋中部海域;在CP（Central-Pacific）型El Niño事件期间,异常低值时空簇分布在太平洋中部,而异常高值时空簇分布在南太平洋与西太平洋海域;② 在EP型La Niña事件期间,赤道太平洋中部及东部、赤道大西洋与印度洋海域出现异常高值时空簇,南太平洋中东部海域出现异常低值时空簇;在CP型La Niña事件期间,赤道太平洋中部出现异常高值时空簇;南太平洋中西部海域出现异常低值时空簇;③ 发生在赤道太平洋的海洋初级生产力时空演变簇,在EP型ENSO事件期间具有东移特征,而在CP型ENSO事件期间,时空演变簇在赤道太平洋中部海域产生并消亡;④ ENSO事件中海洋初级生产力时空演变簇面积与MEI具有较强相关性。     

夏冬季热带太平洋、印度洋海表温度年际异常的年代际变化

用Nino 3指数、印度洋单极指数、偶极子指数描述热带太平洋、印度洋海表温度 (SST)的年际异常 ,季节分析表明 :冬季Nino3区与热带印度洋海表温度距平 (SSTA)相互关系表现为单极 ,且 1976年以后两者的相互关系减弱 ,其可能原因 :一是冬季是ENSO(厄尔尼诺 )事件的盛期 ;二是冬季西太平洋暖水区东移 ,造成两洋的垂直纬向环流耦合减弱。夏季两者相互关系表现为偶极 ,1976年以后两者的相互关系加强 ,其可能原因 ,一是夏季是偶极子盛期 ,ENSO事件的发展期 ;二是夏季西太平洋暖水区虽然东移 ,但暖水区位置偏北 ,且东南印度洋的上升支强度增大 ,造成两洋的纬向环流耦合更强烈     

The Upper Ocean Thermal Structure and the Genesis Locations of Tropical Cyclones in the South China Sea

The relationship between the upper ocean thermal structure and the genesis locations of tropical cyclones （TCs） in the South China Sea （SCS） is investigated by using the Joint Typhoon Warning Center （JTWC） best-track archives and high resolution （1/4 degree） temperature analyses of the world＇s oceans in this paper In the monthly mean genesis positions of TCs from 1945 to 2005 in the SCS, the mean sea surface temperature （SST） was 28.8℃ and the mean depth of 26℃ water was 53.1 m. From the monthly distribution maps of genesis positions of TCs, SST and the depth of 26℃ water in the SCS, we discovered that there existed regions with SST exceeding 26℃ and 26℃ water depth exceeding 50m where no tropical cyclones formed from 1945 to 2005 in the SCS, which suggests that there were other factors unfavorable for TC formation in these regions.     

Analyzing and forecasting climate change in Harbin City,Northeast China

Based on sounding data from 1975 to 2005 and TM/ETM+ remote sensing images in 1989, 2001 and 2007, the climate changes in Harbin City, Northeast China in recent 30 years were analyzed and forecasted. Results show that in the lower troposphere the meridional wind speed and mean annual wind speed decrease, and in the lower stratosphere the temperature decreases while the meridional wind speed increases significantly. In the study area, the climate is becoming warmer and wetter in the middle lower troposphere. The expansion of urban area has great effects on the surface air temperature and the wind speed, leading to the increase of the surface air temperature, the decrease of the surface wind speed, and the increase of the area of urban high temperature zone. The quantitative equations have been established among the surface air temperature, the carbon dioxide (CO₂) concentration and the specific humidity (the water vapor content). It is predicted that the future increasing rate of the surface air temperature is 0.85°C/10yr if emission concentration of CO₂ remains unchanged; if emission concentration of CO₂ decreases to 75%, 50% and 25%, respectively, the surface air temperature will increase 0.65°C/10yr, 0.46°C/10yr and 0.27°C/10yr, respectively. The rise of the surface air temperature in the study area is higher than that of the global mean temperature forecasted by IPCC.     

CHARACTERISTICS OF ZONAL ANOMALY OF ANNUAL PRECIPITATION IN THE NORTHEASTERN CHINA

The characteristics of zonal anomaly and change rule of temporal distribution of annual precipitation in the northeastern China are revealed in this paper with EOF (Empirical Orthogonal Function) and REOF (Rotated Empirical Orthogonal Function) methods and results are drawn in the standard relief maps with GIS technology for practical application. Data used in the study were obtained from 208 meteorological stations over the northeastern China from 1961 to 2001. EOF results show that the first 3 loading vectors could give entire spatial anomaly structure of annual precipitation. In the Northeast Plain including the Songneng Plain and the Liaohe Plain, there is a regional compatibility (whether wet or dry) of annual precipitation change and this precipitation pattern has occurred since the late 1980s to the present. There also exist annual precipitation patterns of wet (or dry) in south and dry (or wet) in north and wet (or dry) in east and dry (or wet) in west. REOF results display 8 principal precipitation anomaly areas by the first 8 rotated loading vectors: the west plain, the Liaodong hills, the Sanjiang Plain, the Liaoxi hills,the Changbai Mountains, the Hulun Buir Plateau, the southwest plateau and the Liaodong Peninsula.     

20世纪80年代初以来北太平洋海温变化特征

应用1979.1-2006.12北太平洋海表温度（SST）资料,采用一元线性回归、功率谱等统计方法对该区SST的变化特征进行分析,结果表明：（1）北太平洋SST年际变化较为显著,尤其在靠近亚洲大陆一带洋面、北太平洋中部中纬度海域及赤道中、东太平洋;（2）北太平洋西部和中部SST1-12月均呈上升趋势,靠近亚洲大陆的日本海一带和我国大陆以东洋面升温最快。除我国以东洋面升温中心在冬季外,其余海域升温均在夏秋季更迅速,20世纪90年代初以来尤为明显;北美海岸山脉以西及赤道中、东太平洋SST则呈弱的下降趋势;（3）赤道中、东太平洋春夏季存在显著5a和3.5a左右的年际变化;北太平洋中部30°N一带冬春季存在5-6a左右的年际变化和约14a的年代际变化;（4）除北太平洋中部（西风漂流区）外,各个海域大部分月份SST高值年和低值年分别与厄尔尼诺年和拉尼娜年对应,西风漂流区SST高值年均出现在20世纪末21世纪初,低值年与厄尔尼诺年对应。