我国南方地区夏季低温变化特征及其成因

采用中国气象局整编的日平均气温资料、NCEP/NCAR再分析日平均资料,分析了1960-2004年我国南方地区尤其是长江中下游地区夏季低温的变化特征及成因.结果表明:我国南方地区夏季气温在20世纪70年代末出现一个转折,在此之前气温普遍偏低,在此之后气温普遍升高;江南地区是夏季低温频发且强度较大的区域;各个层次高度场环流形势的变化以及降水和总云量的变化都对夏季低温的形成有一定作用.     

气候变化检测与诊断技术的若干新进展

近年来,全球气候变暖及其对世界经济的影响已经引起了社会各界的关注和重视,判断当前全球的温度变化趋势,已经成为研究气候变化的一个至关重要的问题。进一步发展新的气候变化检测技术以适应全球增暖的新特征则显得尤为重要。因此,结合（1）气候突变和转折检测技术、（2）观测数据信息的分离和提取、（3）气候系统内在复杂性、（4）气候系统动力学结构特征的识别、（5）极端气候事件定义及其检测等方面的气候变化检测技术研究,分别介绍了中国近期气候变化检测技术的研究进展及部分研究成果,主要侧重于新检测技术和方法的介绍。最后,就当前气候变化检测技术方面的一些焦点和难点问题做了简单的讨论。     

Cartography and Population Geography as Current Events: A Case Study

Abstract

The Sanders housing lawsuit in Pennsylvania provides a case study of how to incorporate current events into the teaching of cartography or population geography at the high school or college level. Settlement of the Sanders case resulted in the release of information about the segregation of public housing by race in the Pittsburgh area. The issues in the Sanders case were mapped using publicly-accessible data, illustrating how an authentic lesson can be created with a minimum of resources.     

萨拉乌苏河流域高分辨率的沙丘砂常量元素分布指示的全新世寒冷事件

The components of the primary elements in the dune sands for the MGS1 subsection of the Milanggouwan section in the Salawusu River valley, compared with those of modern dune sands, show that they were caused by East Asian winter monsoon in the Mu Us desert during Holocene. The examined ages for the 11 layers of dune sands, based on the average sedimentary rate, are： 0 to 960, 1350-2240, 2470 to 3530, 4000 to 4180, 4290 to 4350, 4380 to 4760, 5040 to 5920, 6570 to 8270, 9020 to 9700, 9880 to 10160 and 10580 to 11080 a BP, respectively. The climatic events indicated by these dune sands are consistent with those records in the Huguangyan volcanic lake, Zoige peat bog, Hulu cave and Dunde ice core, particularly with the climatic fluctuations of the North Atlantic since 11 000 a BP. Among them, patterns from B0 to B8 correspond to the peak values of 0MD, 2D, 4D, 6D＋8D＋10D, 12D, 14D, 16D, 18D and 20D respectively. It might be caused by the North Atlantic ice age induced by the heat circulation, which strengthened the polar high pressure and Siberian-Mongolian high pressure and further led to the dominance of the winter monsoon over China＇s desert area.     

Paleo-environmental changes in the Yangtze Delta during past 8000 years

The Yangtze Delta is one of the economically most developed areas in China. It is located in the eastern China monsoon region. Archaeological excavations and environment-archaeology studies over many years in this region provide exceptional information about climate changes, development of human civilization and also human-environment interactions. Archaeological excavations made in the study region reveal that the development of Neolithic cultures is not continuous, which may be a result of extreme climatic events. The analysis of ^14C-dated buried paleotrees, peat and shell ridges show the rise and fall of human civilization in the study area. The research results presented in this paper confirm that human civilization collapsed six times in the Yangtze Delta, matching six high sea level epoches, peat accumulation and buried paleotrees formation periods respectively. This indicates that human activities in the Yangtze Delta are controlled by local climate changes and changing hydrological conditions. The collapse of the Liangzhu culture (5000 aBP-3800 aBP) in about 4000 aBP, after a tremendous flooding event, followed by a relatively backward Maqiao culture (3800 aBP-3200 aBP) confused researchers and aroused their great interest. The research results in this paper show that the collapse of the Liangzhu culture is a result of several factors, for example war and food shortage, but the flooding event occurred in the late Liangzhu culture epoch is the main factor therein.     

INVESTIGATION OF THE SPATIAL AND TEMPORAL DISTRIBUTION OF EXTREME HIGH TEMPERATURE IN CHINA WITH DETRENDED FLUCTUATION AND PERMUTATION ENTROPY

With temperatures increasing as a result of global warming,extreme high temperatures are becoming more intense and more frequent on larger scale during summer in China.In recent years,a variety of researches have examined the high temperature distribution in China.However,it hardly considers the variation of temperature data and systems when defining the threshold of extreme high temperature.In order to discern the spatio-temporal distribution of extreme heat in China,we examined the daily maximum temperature data of 83 observation stations in China from 1950 to 2008.The objective of this study was to understand the distribution characteristics of extreme high temperature events defined by Detrended Fluctuation Analysis(DFA).The statistical methods of Permutation Entropy(PE)were also used in this study to analyze the temporal distribution.The results showed that the frequency of extreme high temperature events in China presented 3 periods of 7,10—13 and 16—20 years,respectively.The abrupt changes generally happened in the 1960s,the end of 1970s and early 1980s.It was also found that the maximum frequency occurred in the early 1950s,and the frequency decreased sharply until the late 1980s when an evidently increasing trend emerged.Furthermore,the annual averaged frequency of extreme high temperature events reveals a decreasing-increasing-decreasing trend from southwest to northeast China,but an increasing-decreasing trend from southeast to northwest China.And the frequency was higher in southern region than that in northern region.Besides,the maximum and minimum of frequencies were relatively concentrated spatially.Our results also shed light on the reasons for the periods and abrupt changes of the frequency of extreme high temperature events in China.     

1976—1977年及1982—1983年厄尔尼诺事件过程差异的年代际背景

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。     

Interannual Variation of Multiple Tropical Cyclone Events in the Western North Pacific

The interannual variability of occurrence of multiple tropical cyclone(MTC) events during June-October in the western North Pacific(WNP) was examined for the period 1979-2006.The number of the MTC events ranged from 2 to 9 per year,exhibiting a remarkable year-to-year variation.Seven active and seven inactive MTC years were identified.Compared to the inactive years,tropical cyclone genesis locations extended farther to the east and in the meridional direction during the active MTC years.A composite analysis shows that inactive MTC years were often associated with the El Nin o decaying phase,as warm SST anomalies in the equatorial eastern-central Pacific in the preceding winter transitioned into cold sea surface temperature(SST) anomalies in the concurrent summer.Associated with the SST evolution were suppressed low-level cyclonic vorticity and weakened convection in the WNP monsoon region.In addition to the mean flow difference,significant differences between active and inactive MTC years were also found in the strength of the atmospheric intraseasonal oscillation(ISO).Compared with inactive MTC years,ISO activity was much stronger along the equator and in the WNP region during active MTC years.Both westward-and northward-propagating ISO spectrums strengthened during active MTC years compared to inactive years.The combined mean state and ISO activity changes may set up a favorable environment for the generation of MTC events.     

区域性极端低温事件的识别及其变化特征

区域性极端低温事件的客观识别方法主要包括4个部分:极端低温阈值的确定、极端低温事件空间区域的识别、空间区域的连续性过程提取和指标体系,结合个例分析验证了该方法在实际低温事件检测中的有效性。从空间分布和时间变化趋势等角度分析了近50年区域性极端低温事件的变化特征:区域性极端低温事件的发生频次较高的纬度带主要位于32°N和42°N附近,区域性极端低温事件的发生频次、强度和最大覆盖面积等存在总体减弱的趋势,在20世纪80年代后期存在显著的转折,90年代后期以来变化逐渐趋于平缓。此外,对各种单一指标与我国冷冻害造成的经济损失和受灾人口之间的相关分析,构建了体现区域性极端低温事件多方面影响的综合指标。     

2010年中国气候概况

2010年,中国年平均气温较常年偏高0.7℃,是1961年以来第10个最暖年,夏季气温达1961年以来历史同期最高.年降水量681 mm,比常年偏多11.1%,为1961年以来第2多.年内,极端天气气候事件频发:西南地区发生历史罕见秋冬春特大干旱.东北、华北发生近40年罕见冬春持续低温,新疆北部出现有气象记录以来最为严...