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1.
Long-term macrobenthos data from Kiel Bight in the Western Baltic collected between 1968 and 2000 have been correlated with the winter NAO index (North Atlantic Oscillation Index) and other environmental data such as temperature, salinity and oxygen content in the bottom water in order to detect systematic patterns related to so far unexplained abiotic signals in the dynamics of zoobenthic species assemblages. The benthos data come from a cluster of five stations (Süderfahrt/ Millionenviertel) in Kiel Bay. Our investigations concentrated on the macrobenthic dynamics with a focus on the number of species m 2 (species richness). Using logarithms and the time series analysis approach of Box/Jenkins (ARIMA modelling, transfer function modelling) it was shown that species richness was strongly influenced by the winter NAO (adjusted for a linear time trend within the 1968-2000 period) and salinity (with a shift/lag of four years). Bootstrapping experiments (i.e. sampling from the error process) and analysis of prediction power (by means of the one- or more-years leaving-out method) showed that the parameter estimates behaved in a stable way, leading to a relatively robust model.  相似文献   
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The discovery of decadal variability of North Atlantic Oscillation (NAO) and the introduction of Arctic oscillation (AO) concept have initiated a series of paleo-AO/NAO related studies since the mid-to-late 1990s. The progress and new findings of paleo-AO/NAO works after that time were comprehensively reviewed. The new results from the observations and modelings at four key timescales were summarized in detail: ①the reconstructions of the AO/NAO annual index over the past millennium; ②the debate on AO/NAO’s trend since early Holocene; ③the weakening of AO/NAO’s amplitude during the Last Glacial Maximum; and ④the anomalous positive phase of AO/NAO during the Last Interglacial. In addition, the possible mechanism for different timescales of AO/NAO is also summarized. Furthermore, the distinction between AO/NAO’ was mean state and amplitude, which were not explicitly separated in previous studies, were comprehensively discussed. Considering the current uncertainties related to paleo-AO/NAO studies, we encourage the community to search for more proxies having longer-than-10,000-year length with annual resolution around AO/NAO highly correlated regions. Another, we encourage long-term transient modeling on AO/NAO can be performed in order to improve our understanding of the dynamics and interaction between AO/NAO’s high-frequency variability and the climatological background, so as to further improve AO/NAO’s predictability on global warming context.  相似文献   
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Large-scale, low frequency modes such as the North Atlantic Oscillation(NAO)and blocking, have an important modulation on the northern hemisphere weather and climate. In this paper, the physical mechanism studies on inter-decadal and decadal variability of NAO and blocking were summarized. The relationship between NAO regime transitions and the interannual variability of NAO in winter during was examined by using a statistical approach. The time-space relationship between NAO and European blocking were discussed. Based on two extreme cold and snowstorm events, the impacts on local weather especially the extreme events within the life cycle (two weeks) of the NAO and blocking were further examined. It was found that the frequently occurrence of the Eurasian extreme snowstorm was closely related to the special combination of NAO and blocking regime. In addition, the development of theoretical modes for NAO and blocking was discussed and issues that remain to be solved were proposed.  相似文献   
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Abstract

To advance understanding of hydroclimatological processes, this paper links spatiotemporal variability in gridded European precipitation and large-scale mean sea-level pressure (MSLP) time series (1957–2002) using monthly concurrent correlation. Strong negative (positive) correlation near Iceland and (the Azores) is apparent for precipitation in northwest Europe, confirming a positive North Atlantic Oscillation (NAO) association. An opposing pattern is found for southwest Europe, and the Mediterranean in winter. In the lee of mountains, MSLP correlation is lower reflecting reduced influence of westerlies on precipitation generation. Importantly, European precipitation is shown to be controlled by physically interpretable climate patterns that change in extent and position from month to month. In spring, MSLP–precipitation correlation patterns move and shrink, reaching a minimum in summer, before expanding in the autumn, and forming an NAO-like dipole in winter. These space–time shifts in correlation regions explain why fixed-point NAO indices have limited ability to resolve precipitation for some European locations and seasons.

Editor Z.W. Kundzewicz; Associate editor A. Montanari

Citation Lavers, D., Prudhomme, C., and Hannah, D.M., 2013. European precipitation connections with large-scale mean sea-level pressure (MSLP) fields. Hydrological Sciences Journal, 58 (2), 310–327.  相似文献   
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利用1961—2008年的逐日降水和气温资料,采用线性趋势、小波功率谱和交叉小波谱等方法分析了新疆降水和气温的变化,以及与北大西洋涛动(NAO)变化之间的关系。结果表明,近50年新疆存在降水增多和气温上升的趋势,有暖湿化现象,这与西北地区由暖干趋于暖湿的结论相一致。同时,新疆平均年降水量与NAO存在准2年和准6年周期,夏季降水量与NAO存在准3年和准5年周期,冬季降水量与NAO存在准3年周期。新疆年均气温与NAO存在准3年周期,夏季气温与NAO存在准3年周期,冬季气温与NAO存在准3年和准8年周期。新疆全年、冬季和夏季的降水与NAO的周期中,通过显著性检验的高值正相关大多集中在20世纪80年代;而气温与NAO的周期中,通过显著性检验的高值正相关也大多集中在80年代。  相似文献   
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北大西洋涛动位相转换的数值研究   总被引:1,自引:0,他引:1  
李忠燕  罗德海 《大气科学》2012,36(2):374-384
借助一个非线性准地转正压模型,模拟了基本西风气流的强弱、不同空间分布的天气尺度扰动涡对北大西洋涛动(NAO)位相转换的作用,以及大尺度双波地形对其的影响.通过一系列的对比试验发现,适当弱的基本西风气流有利于下游系统西退使NAO由正(负)位相转换为负(正)位相;振幅强、活动范围大的天气尺度扰动波是NAO由负位相转换为正位...  相似文献   
9.
The authors present evidence to suggest that variations in the snow depth over the Tibetan Plateau (TP) are connected with changes of North Atlantic Oscillation (NAO) in winter (JFM). During the positive phase of NAO, the Asian subtropical westerly jet intensifies and the India-Myanmar trough deepens. Both of these processes enhance ascending motion over the TP. The intensified upward motion, together with strengthened southerlies upstream of the India-Myanmar trough, favors stronger snowfall over the TP, which is associated with East Asian tropospheric cooling in the subsequent late spring (April--May). Hence, the decadal increase of winter snow depth over the TP after the late 1970s is proposed to be an indicator of the connection between the enhanced winter NAO and late spring tropospheric cooling over East Asia.  相似文献   
10.
刘焕才  许芃  李曼 《地理科学》2021,41(3):544-552
基于1961—2018年降水观测资料,应用经验正交函数分解(EOF)、大气诊断等方法对山西夏季不同等级降水时空演变特征及其影响要素进行分析。结果表明:① 山西夏季降水量主要由大雨贡献(51.9%),但在降水频次上以小雨为主。山西大雨与小雨事件存在显著差异。小雨多年平均雨量由南至北递增,而大雨却由南至北递减。此外,EOF表明全区一致型均是不同等级降水中的主空间模态,但在小雨和大雨中高载荷区存在明显差异。② ENSO在影响山西降水特别是大雨中占据主导,而NAO在小雨中作用更为突出。对大气环流异常结构的诊断分析表明,冷(暖)ENSO位相时,源于热带西太平洋并经由南海北上的季风水汽输送增强(减弱),同时在ENSO和中高纬度大气活动联动调控下,在东亚地区建立的异常反气旋(气旋)可通过其西支南(北)风气流引导(抑制)季风水汽向山西进一步纵深推进,两者共同调配使得山西大雨事件增多(减少);NAO主要通过一条沿西欧?东欧?乌拉尔山?蒙古高原的高纬度路径对降水施加影响,NAO正(负)位相时,在蒙古高原甚至山西建立的深厚异常(反)气旋通过其南支西(东)风一方面阻挡低纬度季风水汽进入山西,另一方面增强(减弱)山西有限的内陆水汽供应,从而引起山西小雨事件的增多(减少)。  相似文献   
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