El Nino事件的概率预测研究

根据19８５４－１９９３年期间的ＥlNino事件资料序列，通过正态性，独立性等统计检验，确定序列的性质，利用Ｍarkov随机过程和一阶自回归建立预测模式，给出了下次发生ＥlNino事件的时间可能在２００２年前后，２００１年发生的概率为４４％，２００２年发生的概率为６１％。     

The Relationship between the Meridional Profile of Zonal mean Geostrophic Wind and Station Wave at 500 hPa

The sea-level pressure (SLP), 500 hPa height, zonal-mean 500 hPa height ([Z500]), stationary wave ed dy component of the 500 hPa height (Z*500) and zonal-mean 500 hPa geostrophic wind [Ug ] fields poleward of 20°N are examined for the period 1958-1997, with emphasis on the winter season. The relationships be tween the Arctic Oscillation (AO)index and algebraic difference of the zonal-mean wind in 55°N and 35°N (Ut) index were investigated, making use the Monte Carlo procedure, Singular Value Decomposition (SVD), Empirical orthogonal function (EOF) and regression method. The leading modes of empirical orthogonal function (EOF＇s) of SLP are more robust than the 500 hPa height EOF＇s, not only in the ratio of the two largest eigenvalues, but in more zonally symmetric. Comparing the meridional profiles of zonal-mean wind amplitude associated with the AO and Ut index, the profiles for the two indexes are very similar, both with respect to amplitude and the placement of the maximum and minimum. Comparing the station wave component of 500 hPa height field regressed upon the AO and Ut index, there is one-to-one correspondence between all the major centers of action in the two maps, especially in the North Atlantic and Eurasian continent. The pattern is unlike the prominent teleconnection patterns, they have hemispheric ex tent and cannot be interpreted in term of the individual wavetrains.     

North Atlantic Oscillation – Concepts And Studies

This paper aims to provide a comprehensive review of previous studies and concepts concerning the North Atlantic Oscillation. The North Atlantic Oscillation (NAO) and its recent homologue, the Arctic Oscillation/Northern Hemisphere annular mode (AO/NAM), are the most prominent modes of variability in the Northern Hemisphere winter climate. The NAO teleconnection is characterised by a meridional displacement of atmospheric mass over the North Atlantic area. Its state is usually expressed by the standardised air pressure difference between the Azores High and the Iceland Low. ThisNAO index is a measure of the strength of the westerly flow (positive with strong westerlies, and vice versa). Together with the El Niño/Southern Oscillation (ENSO) phenomenon, the NAO is a major source of seasonal to interdecadal variability in the global atmosphere. On interannual and shorter time scales, the NAO dynamics can be explained as a purely internal mode of variability of the atmospheric circulation. Interdecadal variability maybe influenced, however, by ocean and sea-ice processes.     

地球自转与El Nio——海气耦合理论

从低纬的海气耦合的浅水模式方程组出发 ,运用正交模和特殊函数的方法进一步讨论地球自转速率变化对海气耦合系统的影响 .研究表明 :地球自转速率的变化通过海气耦合一方面使大气和海洋的Kelvin波和Rossby波的移动及稳定性发生变化 ,另一方面使纬向风、洋流和海表温度发生变化 .特别是在地球自转减慢时 ,通过海气耦合 ,出现纬向风和洋流异常和大洋东部海表温度增加 ,从而导致引起全球气候异常的ElNi no现象     

The impact of recent climate change on flooding and sediment supply within a Mediterranean mountain catchment,southwestern Crete,Greece

This paper presents work from a geomorphological investigation carried out in the Aradena Gorge, southwestern Crete, Greece. The gorge is typical of many steepland fluvial systems in the Mediterranean, with steep relief, coarse‐gravel sediments and high rates of sedimentation generated during intense winter storm events. Hillslope deposits and coarse‐gravel flood units within a 5 km section of the gorge have been mapped, dated (using lichenometry and dendrochronology), and their sedimentological characteristics recorded to establish a c. 200‐year record of flood frequency/magnitude and hillslope/channel sediment supply variability. This record has been compared with instrumented and previously published records of climate change from Crete and the Mediterranean region and used to establish the major controls on flooding and sediment dynamics within the Aradena Gorge. Rates of colluviation and sediment delivery to the channel appear to have been greater than the present sometime before c. AD 1800 and may be related to cooler climates with a more seasonal precipitation regime during the Little Ice Age (c. AD 1450 to 1850). In gorge sections where the present rate of sediment supply from hillslope colluvium is very low, the channel has incised into older alluvial and colluvial deposits. Conversely, in the few sections where sediment supply is currently very high, the channel is aggrading with a braided pattern. Major rock‐fall deposits at certain locations in the gorge have restricted any major downstream sediment transfer. Twelve periods of increased flooding during the last 150 years have been identified and these correlate quite well with negative or declining phases of the North Atlantic Oscillation (NAO). Analysis of daily precipitation data from Crete suggests negative phases of the winter NAO are characterized by an increase in the number of long‐duration, high‐intensity storms. These storms, particularly those with five‐day and greater duration, appear to be significant in triggering major floods in the Aradena Gorge. During the last 40 years the NAO index has been increasing and become locked into a positive phase. As a consequence of this, major flooding appears to have declined during the same period. Copyright © 2002 John Wiley & Sons, Ltd.     

An 8000-year record of vegetation, climate, and human disturbance from the Sierra de Apaneca, El Salvador

An ∼8000-cal-yr stratigraphic record of vegetation change from the Sierra de Apaneca, El Salvador, documents a mid-Holocene warm phase, followed by late Holocene cooling. Pollen evidence reveals that during the mid-Holocene (∼8000-5500 cal yr B.P.) lowland tropical plant taxa were growing at elevations ∼200-250 m higher than at present, suggesting conditions about 1.0°C warmer than those prevailing today. Cloud forest genera (Liquidambar, Juglans, Alnus, Ulmus) were also more abundant in the mid-Holocene, indicating greater cloud cover during the dry season. A gradual cooling and drying trend began by ∼5500 cal yr B.P., culminating in the modern forest composition by ∼3500 cal yr B.P. A rise in pollen from weedy plant taxa associated with agriculture occurred ∼5000 cal yr B.P., and pollen from Zea first appeared in the record at ∼4440 cal yr B.P. Human impacts on local vegetation remained high throughout the late Holocene, but decreased abruptly following the Tierra Blanca Joven (TBJ) eruption of Volcán Ilopango at ∼1520 cal yr B.P. The past 1500 years are marked by higher lake levels and periodic depositions of exogenous inorganic sediments, perhaps indicating increased climatic variability.     

厄尔尼诺事件研究的新进展

简述了厄尔尼诺事件研究的最新进展，研究表明：强潮汐加大垂直方向和水平方向海水的混合，将太平洋深层冷水翻上表面（或使西部暖水流向东部），吸收（或释放）CO2减弱（或增强）温室效应，使海洋上方空气变冷（或变暖），产生拉尼娜冷事件（或厄尔尼诺热事件）。海底火山活动亦受强潮汐的控制。     

Atmospheric and Climatic Hazards: Improved Monitoring and Prediction for Disaster Mitigation

Natural Hazards - The last few years have seen enormous damage and lossof life from climate and weather phenomena. The mostdamaging events have included the severe 1997/98 ElNiño (with its...     

厄尔尼诺的发生与赤道西太平洋暖池次表层海温异常

通过资料分析研究了厄尔尼诺事件的爆发与西太平洋暖池次表层海温正异常的重要关系。结果表明，El Ni?o事件之前暖池次表层海温都有明显的持续升高；这种暖池次表层海温正距平的出现，尤其是它向赤道中东太平洋的传播对 El Ni?o事件的爆发有直接关系，是导致El Ni?o事件的重要原因。分析还表明，暖池次表层海温正距平的东移原因在于赤道西太平洋地区西风异常的发生和向东扩展。     

自适应原理在尺度分离技术中的应用

采用1951—1986年月平均北大平洋海表面温度(SST)、500hPa高度、副高特征量以及华北降水资料,分析了北太平洋SST涛动的时空特征及其与夏季副高、华北降水之间的关系,进而讨论了四月SST涛动偏强(弱)对八月副高偏强(弱)、副高脊线偏南(北)和华北降水偏弱(强)的影响过程.