北半球阻塞高压的维持Ⅱ:瞬变扰动强迫和平均流位涡平流的形成

着重探讨大西洋阻高和东亚阻高个例中瞬变扰动位涡（涡度）输送强迫和太平洋阻高中平均流位涡平流的形成机理。结果表明，扰动在阻高西南部西风分流区因形变而产生的扰动拟能向更小尺度串级过程，并不是扰动位涡输送强迫形成的必要机理。扰－流相互作用在阻高西（北）部非分流气流中也十分显著。数值试验表明，这一相互作用也可能是扰动强迫作用形成的机理。而青藏高原和附近海陆对比的强迫作用则可能是太平洋阻高中平均流的位涡平流形成的重要因素。对比分析表明，阻高维持机制的地域性差别可能与其上游（如青藏高原地区、落基山脉）地形和热源强迫作用不同有关。     

北半球50条山地冰川近期的物质平衡状况

近期北半球大多数山地冰川的物质平衡为负,冰川普遍退缩,表明北半球气候暖化的趋势.由于区域气候波动和变化的差异性以及冰川对气候变化的敏感性(响应程度)的不同,北半球山地冰川在普遍退缩的背景下具有鲜明的区域特征.     

南半球热带外准半年振荡及IAP 9L AGCM模拟检验

基于1979—2000年的NCEP/NCAR海平面气压和位势高度场资料分析了南半球大气环流的准半年振荡 (半年波) 现象。结果表明:这一现象主要出现在南半球对流层低层的中高纬度和中高层的热带地区。对南半球热带外大气而言, 40°S和65°S是低层大气环流准半年振荡最为显著的两个纬度带, 半年波的贡献都超过了70%, 低层南半球中高纬度海平面气压场季节变化的反位相也主要体现为各自半年波分量变化的反位相。在此基础上, 检验了IAP 9L AGCM (大气物理研究所9层大气环流模式) 对这一现象模拟的能力, 模拟结果显示, 模式成功模拟了65°S处海平面气压场的准半年振荡现象, 其振幅略低于观测结果, 但模式对40°S处气压场准半年振荡的模拟效果较差。     

IMPACT OF SSTA OF SOUTHERN HEMISPHERE ON FLOOD SEASON PRECIPITATION ANOMALIES IN YUNNAN

Based on the reanalysis data of monthly mean global SST and wind from the NCEP/NCAR and the observation data of rain seasons in 124 stations of Yunnan province from 1961 to 2006, we applied the analytical methods of correlation analysis and composite analysis and a significance testing method to two sets of samples of average differences. The goal is to investigate into the influence of the Southern Hemispheric (SH) SST on the summer precipitation in Yunnan from January to May so as to identify the key time and marine regions. Physical mechanisms are obtained by analyzing the influence of sea level wind and the key marine regions on the precipitation during Yunnan’s rain season. Results show that there is indeed significant relationship between the SST in SH and summer precipitation in Yunnan. The key areas for influencing the summer precipitation are mainly distributed in a region called “West Wind Drift” in the SH, including the Southeast Indian, southern Australia, west coast of eastern Pacific off Chile, Peru and the southwest Atlantic Magellan. Besides, the most significant marine region is the west coast of Chile and Peru (cold-current areas of the eastern Pacific). Diagnostic analysis results also showed that monsoons in the Bay of Bengal, a cross-equatorial flow in the Indian Ocean near the equator and southwest monsoon in India weaken during the warm phase of the Peruvian cold current in the eastern Pacific. Otherwise, they strengthen.     

The watermass variability and southward shift of the Southern Hemispheremid-depth supergyre

The Southern Hemisphere subtropical supergyre at intermediate depths connects all three ocean basins and plays a significant role in responding and conveying the climate-change-related variations in the glob- al ocean. On the basis of the Simple Ocean Data Assimilation/SODA） ocean reanalysis, the thermohaline variability and southward shift of the mid-depth supergyre are demonstrated. The steric height of the sub- surface relative to 1 500 m （400-1 500 m） from the SODA depicts exactly the flow patterns and variability of the oceanic supergyre. During 1958-2007 the water masses in the gyre interiors become cooler/fresher, with the significant exceptions of the Agulhas Current system and Agulhas leakage. The results also exhibit a pronounced strengthening of the inter-basin connection of the supergyre, and the strongest southward shift, by about 2.5° over the whole period, occurs in the central-south Pacific, which is associated with the changes in the basin-scale wind forcing.     

The Southern Annular Mode (SAM) in PMIP2 simulations of the last glacial maximum

The increasing trend of the Southern Annular Mode （SAM） in recent decades has influenced climate change in the Southem Hemisphere （SH）.How the SAM will respond increased greenhouse gas concentrations in the future remains uncertain.Understanding the variability of the SAM in the past under a colder climate such as during the Last Glacial Maximum （LGM） might provide some understanding of the response of the SAM under a future warmer climate.We analyzed the changes in the SAM during the LGM in comparison to pre-industrial （PI） simulations using five coupled ocean-atmosphere models （CCSM,FGOALS,IPSL,MIROC,HadCM） from the second phase of the Paleoclimate Modelling Intercomparison Project （PMIP2）.In CCSM,MIROC,IPSL,and FGOALS,the variability of the simulated SAM appears to be reduced in the LGM compared to the PI simulations,with a decrease in the standard deviation of the SAM index.Overall,four out of the five models suggest a weaker SAM amplitude in the LGM consistent with a weaker SH polar vortex and westerly winds found in some proxy records and model analyses.The weakening of the SAM in the LGM was associated with an increase in the vertical propagation of Rossby waves in southern high latitudes.     

BOOK REVIEWS

Book Reviewed in this article: Marine Resources of Kuwait: Their Role in the Development of Non-oil Resources . Fatimah H. Y. al -Abdul -Razzak Recollections of a Revolution: Geography as Spatial Science . Mark Billinge , Derek Gregory and Ron Martin Entre l'Eden et l'Utopie . Luc Bureau Developments in Political Geography . M. A. Busteed The Elements of Graphing Data . William S. Cleveland Rural Resource Management . Paul J. Cloke and Chris C. Park Third World Atlas . Ben Crow and Alan Thomas Exploitation, Conservation, Preservation: A Geographic Perspective on Natural Resource Use . Susan L. Cutter , Hilary Lambert Renwick, and William H. Renwick . Wine Regions of the Southern Hemisphere . Harm Jan de Blij Regional Development: Problems and Policies in Eastern and Western Europe . George Demko The Geographer at Work . Peter R. Gould Change in the Amazon Basin . John Hemming Geography Since the Second World War . R. J. Johnston and P. Claval Urbanization in China: Town and Countryside in a Developing Economy 1949–2000 A.D. , R. J. R. Kirkby Transport and Communications for Pacific Microstates: Issues in Organisation and Management . Christopher C. Kissling Fluvial Forms and Processes . David Knighton The Urban Millennium . Josef W. Konvitz Technological Transition in Cartography . Mark Stephen Monmonier Field Guide to Soils and the Environment: Applications of Soil Surveys . Gerald W. Olson Northern Australia: The Arenas of Life and Ecosystems on Half a Continent . Don Parkes A Killing Rain: The Global Threat of Acid Rain . Thomas Pawlick From the Family Farm to Agribusiness: The Irrigation Crusade in California and the West, 1850–1931 . Donald J. Pisani Hybrid Maize Diffusion in Kenya . Franz -Michael Rundquist Warning and Response to the Mount St. Helens Eruption . Thomas F. Saarinen and James L. Sell Coastal Geomorphology in Australia . B. G. Thom Tropical Rain Forests of the Far East , 2nd ed . T. C. Whitmore The Dark Side of the Earth . Robert Muir Wood Categorical Data Analysis for Geographers and Environmental Scientists , Neil Wrigley     

Paleoclimate changes during the last 100,000 yr from a record in the Brazilian Atlantic rainforest region and interhemispheric comparison

A long terrestrial record, Colônia CO-3, from the Atlantic rainforest region in Brazil (23°52′S, 46°42′20 W, 900 m a.s.l.) registrates variations in the forest expansion during the last 100,000 yr. The 780-cm depth core was analyzed at 2-cm intervals and arboreal pollen frequencies were compared to nearby speleothem stable isotope records and neighboring marine records from the tropical Atlantic. To evaluate regional versus global climate forcing, our record was compared with Greenland and Antarctic ice-core records. These comparisons suggest that changes in temperature seen in polar latitudes relate to moisture changes: e.g., to changes in the length of the dry season, in tropical and subtropical latitudes during glacial as well as interglacial times. These climatic changes result from changes in the frequency of polar air incursions to these latitudes inducing a permanent cloud cover and precipitation. This is an important result that should help define paleoclimatic features in the Southern Hemisphere for the last glaciation.     

山西芦芽山地区树木年轮记录的1676 AD以来5～7月温度变化

在山西芦芽山地区采取了符合国际树轮库要求的油松样本,通过交叉定年和应用区域生长模型,建立长度为328 a的标准宽度年表.根据RCS序列所揭示的气候低频变化特征,确定1676 AD以来夏季温度可划分为两个时段:1676—1865 AD和1866—2003 AD.在1676—1865 AD时期,夏季温度变化主要表现为“冷强暖弱”,其中1710—1720s为最冷时段.1866—2003 AD时期,夏季温度呈现出“总体持续变暖,冷暖交替频繁”的变化特征.     

北大西洋飓风频次与西半球的南极涛动的联系

To examine the zonal asymmetry of the Antarctic oscillation （AAO）, different portions of the AAO from June to October （JJASO） in the interannual variability of the Atlantic tropical hurricanes number （ATHN） are documented in this research. It follows that the AAO in the Western Hemisphere （AAOWH） is positively correlated with the ATHN, at 0.36 during the period of 1871-1998 and 0.42 during the period of 1949-98. After removing the linear regressions on the Southern Oscillation Index （SOI） in all time series, the above correlation coefficients are 0.25 and 0.30, respectively. The underlying mechanisms are studied through analyses of the atmospheric general circulation variability associated with the AAOWH. It turns out that the positive （negative） phase of JJASO AAOWH corresponds with several factors： decreased （increased） vertical zonal wind shear magnitude, low-level anomalous convergence （divergence）, high-level anomalous divergence （convergence）, and warmed （cooled） sea surface temperature in the tropical Atlantic. Therefore, the positive （negative） phase of JJASO AAOWH is favorable （unfavorable） to the tropical hurricane genesis.