Interannual and Interdecadal Variations of the Mid-Atlantic Trough and Associated American-Atlantic-Eurasian Climate Anomalies     

Mengmeng Lu  Kaiqiang Deng  Guojun Zhou  Yaheng Tan 《大气与海洋》2017,55(4-5):284-292

The mid-Atlantic trough (MAT) is one of the most prominent circulation systems over the subtropical North Atlantic during the boreal summer, and it can be viewed as a bridge linking the climate in the American-Atlantic-Eurasian region. The upper-tropospheric MAT attains its maximum intensity of 200–150?hPa in June and July. An index measuring the variability of MAT intensity is defined, which reveals significant interannual and interdecadal variations of the trough.

On interannual time scales, the variation of MAT is significantly associated with the North Atlantic Oscillation, a southeastward propagating stationary wave that possibly originates from the northeastern Pacific, and the Atlantic Meridional Mode. A stronger trough is associated with warmer surface temperatures and higher pressure over central-northern North America and the extratropical North Atlantic and with colder surface temperatures and lower pressure over the Arctic, the subtropical North Atlantic, and the northeastern Pacific. In the meantime, significant negative precipitation anomalies occur over the north of the Mediterranean Sea and the Black Sea, as well as the northeastern Atlantic because of the anomalous low-level northeasterly winds over these areas. On an interdecadal time scale, the variation of MAT seems to be related to the Atlantic Multi-decadal Oscillation. Warmer surface temperatures appear over almost the entire North Atlantic, southern Europe, East Asia, and the North Pacific during the weak phase of the trough. A weak trough is also associated with the dipole pattern of anomalous precipitation over the extratropical North Atlantic, Greenland, and northeastern North America, corresponding to a dipole of low-level atmospheric circulation over these regions.  相似文献   

Interdecadal Variability of the ENSO–North Pacific Atmospheric Circulation in Winter     

Peng Zhang  Hua Chen 《大气与海洋》2017,55(2):110-120

The interdecadal change in the relationship between the El Niño–Southern Oscillation (ENSO) and atmospheric circulation over the North Pacific is investigated using both observational data and an atmospheric general circulation model. There are two prominent modes of winter mid-latitude atmospheric variability in the North Pacific: the West Pacific (WP) teleconnection and the Aleutian Low (AL). The relationship between ENSO and the WP-AL patterns changed notably around the late 1970s. From 1957 to 1975, during the mature phase of ENSO, significant sea surface temperature anomalies (SSTAs) occurred, mainly in the equatorial eastern Pacific Ocean; the associated atmospheric circulation anomaly pattern resembles the negative phase of a WP teleconnection pattern. In contrast, for the 1978–2011 period, significant negative SSTAs were observed in the western and extratropical Pacific in both hemispheres, with some significant positive SSTAs appearing over the eastern Pacific. This is in agreement with the defined regions of a mega-ENSO, the associated atmospheric circulation anomaly pattern resembles the AL mode. Further analysis suggests that a negative–positive anomaly pattern in the 500?hPa geopotential height throughout the entire North Pacific, possibly enhanced by the SSTAs in the extratropical North Pacific associated with the mature phase of ENSO, is responsible for modulating the relationship between ENSO and the North Pacific atmospheric circulation.  相似文献   

华南夏季降水20世纪90年代初的年代际变化及其与南亚高压关系          下载免费PDF全文

伯忠凯  曾刚  武英娇  李忠贤  史丹妮 《山东气象》2017,37(2):65-73

分析资料,应用1978—2008年全球逐月观测海表温度驱动NCAR CAM5.1全球大气环流模式进行数值模拟,探讨了华南夏季降水的年代际变化特征及其与南亚高压的关系。结果表明,华南夏季降水与南亚高压的东伸脊点关系密切,均在20世纪90年代初存在年代际转变。在1993—2008（1979—1992）年期间,南亚高压位置偏西（东）,西北太平洋副热带高压位置偏东（西）,华南地区则低层辐合（辐散）异常、高层辐散（辐合）异常,产生异常上升（下沉）运动,华南地区降水年代际偏多（少）,这也被数值试验结果所验证。  相似文献   

热带西北太平洋与东南印度洋对流活动年际变化联系的年代际改变          下载免费PDF全文

张奔奔  管兆勇  张萌萌 《大气科学学报》2018,41(6):753-761

采用美国NOAA卫星观测OLR (outing longwave radiation)资料以及NCEP/NCAR、CM AP月平均资料,利用合成分析等方法,研究了热带西北太平洋(125°～140°E,10°～20°N)与热带东南印度洋(90°～105°E,5°～15°S)对流活动异常的联系。结果表明:热带西北太平洋与东南印度洋对流活动异常的联系有显著的年代际变化; 20世纪80—90年代存在显著的正相关,20世纪90年代至21世纪初有显著的负相关,其后转变为正相关。合成分析表明,热带西北太平洋与东南印度洋对流活动正相关时,两地区均存在反气旋性环流,低层辐散、高层辐合,对流活动弱,不利于降水产生,有降水负异常;当热带西北太平洋与东南印度洋对流活动负相关时,两地区环流异常存在明显差别,热带东南印度洋有正的海温异常,高层辐散、低层辐合,有上升运动,对流活动强,有降水正异常,而热带西北太平洋则相反。热带西北太平洋和热带东南印度洋之间的斜向垂直环流圈将这两个地区联系起来,并决定了这两个地区对流活动负相关关系的形成。  相似文献   

中国6个CMIP5模式对全球降水年际-年代际变率模拟的定量评估   总被引：1，自引：1，他引：0  

王铭昊  李焕连  孙小婷 《气象》2018,44(5):634-644

本文利用美国全球降水气候中心(GPCC)的降水资料和中国参加国际第五阶段耦合模式比较计划(CMIP5)的6个气候模式[BCC_CSM1.1、BCC_CSM1.1(m)、BNU-ESM、FGOALS-s2、FGOALS-g2和FIO-ESM]的历史模拟试验的降水数据,采用可以表征降水变率相对和绝对量级的方法,定量评估了6个模式对降水年际-年代际变率的模拟能力。研究表明,观测降水的年际变率一般占总方差的65%~80%,年代际变率占总方差的10%~35%。在CMIP5历史试验中,6个模式平均的降水年际分量方差对总方差的贡献(超过70%)较观测偏强,模拟降水年代际分量的方差对总方差的贡献较小(约为10%~20%)。模式总体低估了全球平均总降水、年际降水和年代际降水的变率,但是高估了年际降水对总降水的贡献、低估了年代际降水对总降水的贡献。与观测相比,6个模式对东亚和澳大利亚地区的年代际降水的模拟都比较好,模拟与观测年代际降水方差的比值为1左右。在非洲、南美洲和海洋性大陆,BCC_CSM1.1模式模拟的降水年代际变率最接近观测;在欧亚和北美,BNU-ESM模式模拟的降水年代际变率与观测最接近。在欧亚大陆上,BCC_CSM1.1模式模拟的降水年际分量与年代际分量的方差比最接近观测;在非洲和美洲,FGOALS-s2模式模拟的降水年际分量与年代际分量的方差比最接近观测。本文的研究结果有助于理解中国当前气候模式对降水年际-年代际变率的模拟能力,以及未来改进模式。  相似文献   

1976—1977年及1982—1983年厄尔尼诺事件过程差异的年代际背景   总被引：11，自引：3，他引：8  

朱乾根  葛旭阳  矫梅燕 《气象科学》1998,18(3):203-213

本文根据NMC客观分析资料进行诊断分析,揭示了1976－77年及1982－83年这两次ElNino事件海气相互作用过程中的若干特征。结果表明：70年代末赤道西风异常背景场、SST背景场及其准4年周期振荡均存在年代际变化;SST背景场冷（暖）、80°W-0°E赤道区域850hPa纬向风异常西（东）风以及赤道太平洋SSTA准4年周期振荡东传型（西传型）共同决定了这两次事件的强度与类型的差异,即1976／77年事件为较弱的东部型EINino事件,而1982／83年事件表现为很强的西部型EINino事件。  相似文献   

Alternation of the Atmospheric Teleconnections Associated with the Northeast China Spring Rainfall during a Recent 60-Year Period     

Zhiwei ZHU  Rui LU  Shanshan FU  Hua CHEN 《大气科学进展》2023,40(1):168-176

Northeast China(NEC) is China’s national grain production base, and the local precipitation is vital for agriculture during the springtime. Therefore, understanding the dynamic origins of the NEC spring rainfall(NECSR) variability is of socioeconomic importance. This study reveals an interdecadal change in the atmospheric teleconnections associated with the NECSR during a recent 60-year period(1961–2020). Before the mid-1980s, NECSR had been related to a Rossby wave train that is coupled with ex...  相似文献   

TEMPERATURE,RAINFALL VARIATIONS AND THEIR ANOMALIES OVER CHINA UNDER THE COLD-WARM BACKGROUND IN THE 20TH CENTURY          下载免费PDF全文

施能  屠其璞  陈家其 《Acta Meteorologica Sinica》1995,(4)

In this study,the climate trend of the annual average air temperature and total annual rainfall inChina in the present century has been examined.It is noted that in the Northwest,the Northeast andNorth China the climate has become notably warmer this century but the rainfall trend has not beenevident,mainly negative.In the 1980s China's rainfall and temperature showed noticeable regionalfeatures: warm and dry in North China,cold and dry in the Southwest,warm and wet in theNortheast,cold and wet in the middle-lower reaches of the Changjiang River.Besides,the fourinterdecadal climate change features and ranges of this century have been studied.It is found that onthe scale of several decades there was considerably less rainfall in the most part of China in the warmbackground than in the cold background.The increase of temperature which started from the 1970smainly happened in the Northwest and Northeast,while to the south of the Huanghe River thetemperature increase did not even as great as in 1940s.The corresponding rainfall feature is that mostareas experienced much less rainfall except the area to the south of the Huanghe River and over theChangjiang and Huaihe River basin.  相似文献   

冬季黑潮延伸体海表温度变率的年代际变化及其与阿留申大气低压系统的关系   总被引：2，自引：1，他引：1  

余沛龙  张立凤  张永垂  邓冰 《海洋学报(英文版)》2016,35(5):24-37

By utilizing multiple datasets from various sources available for the last 100 years, the existence for the interdecadal change of the winter sea surface temperature(SST) variability in the Kuroshio Extension(KE) region is investigated. And its linkage with the Aleutian Low(AL) activity changes is also discussed. The results find that the KE SST variability exhibits the significant ~6 a and ~10 a oscillations with obvious interdecadal change. The ~6 a oscillation is mainly detected during 1930–1950, which is largely impacted by the anomalous surface heat flux forcing and Ekman heat transport associated with the AL intensity variation. The ~10 a oscillation is most evident after the 1980s, which is predominantly triggered by the AL north-south shift through the bridge of oceanic Rossby waves.  相似文献   

夏季西北太平洋热带气旋生成频次与热带海温关系的年代际变化     

陈慕妍  陈锐丹 《热带气象学报》2022,38(1):58-67

探讨了夏季(6—8月)西北太平洋(Western North Pacific,WNP)热带气旋生成频次(Tropical Cyclone Genesis Frequency,TCGF)与热带海温关系的年代际变化,发现影响WNP TCGF的热带海温型在1991/1992年发生了年代际变化。在1990年代初之前,TCGF正异常对应的热带海温异常(Sea Surface Temperature Anomaly,SSTA)呈现东部型La Ni?a衰减位相,前冬至春季WNP局地暖SSTA在其西北侧激发气旋异常,夏季时由热带印度洋冷SSTA继续维持。在1990年代初之后,TCGF正异常对应的热带SSTA呈现东部型La Ni?a向中部型El Ni?o快速转换的位相,夏季中太平洋暖SSTA在其西北侧激发气旋异常,同时热带东印度洋至海洋性大陆以及热带大西洋的冷SSTA通过垂直环流圈加强中太平洋的辐合上升运动,进一步维持其西北侧气旋异常。由于激发气旋异常的暖SSTA在第二个年代相较第一个年代明显偏南偏东,气旋异常和TCGF正异常在第二个年代也整体偏南且向东扩展至更远的区域。WNP TCGF与热带海温关系的年代际变化与1990年代初之后厄尔尼诺-南方涛动演变速率加快有关。   相似文献