3 万年来亚洲降水与大气环流变化重建和模拟综述

区域性的湖泊水位能反映有效降水及气候变化,已成为重建第四纪降水和水量平衡最重要的指标。亚洲分布着几乎全球各种成因类型的湖泊,第四纪湖泊演化在全球第四纪研究中占有重要地位。多年来通过对地貌学、沉积学、生物地球化学和考古学的研究重建了各个区域的湖泊水位变化,并据此建立了湖泊演变数据库,作为研究第四纪亚洲区域气候变化的重要基础。本文介绍湖泊水位气候理论的发展历程,回顾晚第四纪亚洲湖泊水位研究的历史;分析晚第四纪亚洲从西到东不同区域湖泊水位变化历史和地域特征,并根据晚第四纪冰期和间冰期的两个特征期湖泊空间变化特征,从古气候模拟的角度探讨了气候驱动机制下湖泊水位变化的成因。     

Relationship between land cover and monsoon interannual variations in east Asia

Asian monsoon have multiple forms of variations such as seasonal variation, intra-seasonal variation, interannual variation, etc. The interannual variations have not only yearly variations but also variations among several years. In general, the yearly variations are described with winter temperature and summer precipitation, and the variations among several years are reflected by circulation of ENSO events. In this study, at first, we analyze the relationship between land cover and interannual monsoon variations represented by precipitation changes using Singular Value Decomposition method based on the time series precipitation data and 8km NOAA AVHRR NDVI data covering 1982 to 1993 in east Asia. Furthermore, after confirmation and reclassification of ENSO events which are recognized as the strong signal of several year monsoon variation, using the same time series NDVI data during 1982 to 1993 in east Asia, we make a Principle Component Analysis and analyzed the correlation of the 7th component eigenvectors and Southern Oscillation Index (SOI) that indicates the characteristic of ENSO events, and summed up the temporal-spatial distribution features of east Asian land cover’s inter-annual variations that are being driven by changes of ENSO events.     

Temporal and Spatial Patterns of Seasonal Precipitation Variability in China, 1951-1999

Rainfall variability in China for the period from 1951 to 1999 was investigated. Monthly rainfall data for 160 stations were obtained from the Chinese Academy of Meteorological Sciences. Mean seasonal rainfall amounts were grouped into four distinct precipitation regions by cluster analysis. These regions differed in size and extent in each season and were related to the rainfall-generating mechanism operating at that time of year. The Asian monsoon played a major role in shaping the precipitation regime. Local topography also helped in casting the seasonal variability patterns within regions. To understand the impact of large scale circulation on rainfall variability, areally averaged anomaly percentages were correlated with major atmospheric teleconnection features. It was discovered that the Polar-Eurasia (POL) and Arctic Oscillation (AO) index were positively associated with winter precipitation, indicating the significance of the winter monsoon in producing the rainfall pattern. Negligible effects of the Southern Oscillation Index (SOI), West Pacific (WP), and North Pacific (NP) patterns on precipitation were observed.     

东亚土地覆盖动态与季风气侯年际变化的关系

以东亚地区 １９８２～１９８９年时间序列降水资料及 ＡＶＨＲＲ ８ ｋｍ ＮＤＶＩ数据为基本数据源，应用地理信息系统技术，分别研究了东亚地区夏季（５－９月）降水及土地覆盖的年际变化，并揭示了研究时间段内各自的变化规律。进一步用奇异值分解（ＳＶＤ）模型方法分析了以降水变化为表征的东亚地区气候年际变化与土地覆盖年际变化之间的关系。     

Spatio-temporal Distribution of Drought in the Belt and Road Area During 1998-2015 Based on TRMM Precipitation Data

Drought is a worldwide natural disaster that has long affected agricultural production as well as social and economic activities. Frequent droughts have been observed in the Belt and Road area, in which much of the agricultural land is concentrated in fragile ecological environment. Based on the Tropical Rainfall Measuring Mission Satellite (TRMM) 3B43 precipitation data, we used the Precipitation Abnormity Percentage drought model to study the monthly spatio-temporal distribution of drought in south region of N50° of the Belt and Road area. It was observed that drought during winter was mainly distributed in Northeast Asia, Southeast Asia, and South Asia, while it was mainly distributed in Central Asia and West Asia during summer. The occurrence of historical droughts indicates an obvious seasonal cycle. The regional variations in drought were analyzed using the Breaks for Additive Season and Trend tool (BFAST) in six sub-regions according to the spatial distribution of six economic corridors in the Belt and Road area. The average drought conditions over the 18 years show a slight decreasing trend in Northeast Asia, West Asia, North Africa, South Asia, Central and Eastern Europe, and a slight increasing trend in Central Asia. However, it was a fluctuating pattern of first increasing and then decreasing in Southeast Asia. The results indicate that the total drought area in the Belt and Road region showed a general decreasing trend at a rate of 40,260 km2 per year from 1998 to 2015.     

IMPACT OF THE SOUTHERN OSCILLATION ON THE NORTH AMERICAN SOUTHWEST MONSOON

The intensity and spatial variations in the North American Southwest Monsoon are examined to determine the influence of the Southern Oscillation. Sixty-five years (1920–1984) of July and August monthly precipitation data from Arizona and New Mexico are normalized using a square root transformation, converted into z-scores, and stratified according to onset and following years for Warm Events and Cold Events of the Southern Oscillation. The results for July reveal different spatial patterns in the monsoonal precipitation for the extremes of the Southern Oscillation. Warm-Event onset years are associated with positive precipitation anomalies that decline along a northeast-to-southwest gradient across the study area whereas the Cold-Event onset years produce highest positive values in west-central Arizona and negative values throughout the eastern two-thirds of the study area. Spatial patterns for the August precipitation data do not appear to be influenced by the extremes of the Southern Oscillation. [Key words: Southwest Monsoon, Southern Oscillation, Arizona, New Mexico.]     

季风区边缘近500年的降水变化特征

基于武都万象洞高分辨率石笋δ¹⁸O和高精度²³⁰Th定年数据,结合利用周边地区史料恢复的旱涝指数序列,重建季风区边缘近500 a以来降水变化。结果显示:在年际至百年时间尺度上,万象洞石笋δ¹⁸O变化指示亚洲季风带来的降水量信息。季风区边缘降水变化可分减弱期(1470~1700 A.D.)、平稳期(1701~1875 A.D.)和增强期(1876~2003 A.D.)三个气候段,其间季风降水的强弱变化响应史料记载的极端旱涝事件。在小冰期向20世纪暖期转换过程中,本区呈现阶梯式过渡降水模式,这是一种较大空间尺度上气候特征,在年代际至百年时间尺度上与北半球温度、中国温度变化具有同步性。     

Tree-ring-based drought variability in northern China over the past three centuries

Droughts are the most frequent natural disaster in regions at the margins of the East Asian summer monsoon (EASM),which pose threats to agriculture,the economy,and human lives.However,the limitations of only approximately 60 years of meteorological ob-servations hamper our understanding of the characteristics and mechanisms of local hydro-climate.Trees growing in the marginal region of the EASM are usually sensitive to moisture variations and have played important roles in past hydroclimatic reconstructions.Here,a 303-year tree-ring-width chronology of Pinus tabulaeformis from Mt.Lama,which is located in the junction of the Liaoning Province and Inner Mongolia,China,was used to reconstruct the May-August Palmer drought severity index (PDSI) in the marginal region of the EASM.The transfer function explains 48.0％ (or 47.2％ after adjusting for the loss of the degrees of freedom) of the variance over the calibration period from 1946 to 2012.A spatial correlation analysis demonstrates that our PDSI reconstruction can represent the drought variability on the northernmost margin of the EASM.The winter Asian polar vortex area index showed a delayed impact on the summer EASM precipitation in the following year.     

基于历史帕默尔干旱指数(PDSI)数据集重建的长江源区过去706 a径流量

利用亚洲季风区帕默尔干旱指数(PDSI)重建格点数据集(Monsoon Asia Drought Atlas,MADA)中长江源及附近地区的5个格点序列,通过PDSI与长江源区径流量的相关分析,发现5个格点的第一主成分(PC1)与长江源区夏季(6-8月)平均径流量的相关性最大(r=0.609,N=50,α<0.001)。由此,重建了1300-2005年长江源区夏季径流量变化,并运用独立验证法对重建结果的可靠性进行了检验,运用小波分析方法对重建径流序列进行周期分析。结果表明:近706 a,长江源区经历了显著的丰水期13个、枯水期15个,其中持续时间最长的丰水期为1513-1573年,持续时间最长的枯水期为1389-1414年;重建序列主要存在2~6、10~13、20~26、30~50、50~70 a的显著周期振荡。重建序列与海表温度的相关性表明,长江源区径流变化可能与厄尔尼诺-南方涛动(ENSO)、大西洋年际振荡(AMO)、北大西洋涛动(NAO)、太平洋年代际振荡(PDO)等有关。     

Regionalization and Variability of Precipitation in Hawaii

Regions based on seasonal precipitation variability for Hawaii are determined using a principal components analysis applied to 124 stations for the period 1971-2000. Nine regions are delineated and are consistent with known precipitation patterns; leeward and windward stations are in separate regions on all islands. Within each region, the relationship between precipitation and the El Niño-Southern Oscillation (ENSO) is examined using a correlation analysis with the Southern Oscillation Index (SOI), and the Niño 3.4 and Niño 1+2 indices. Precipitation is most frequently correlated with ENSO in the different regions using SOI and Niño 3.4. Using several nonparametric statistical tests, it is determined that while average precipitation received in Hawaii during El Niño events is significantly different from average precipitation (1971-2000) and from precipitation received during La Niña events, the relationship between precipitation and individual ENSO events within regions is rarely significant. Finally, during El Niño or La Niña events, average precipitation receipt across the regions co-varies during winter and summer under concurrent conditions and a one-season lag. Synoptic patterns are examined and indicate a deviation from average conditions during ENSO events that affects subsidence and precipitation patterns.     

Relationships between variations of the land–ocean–atmosphere system of northeastern Asia and northwestern North America

This study is a broad-scale synthesis of information on climate changes in two Arctic terrestrial regions, eastern Siberia and the Alaska–Yukon area of North America. Over the past 60 years (1951–2010), the trends of temperature and precipitation in the two regions are broadly similar in their seasonality. However, atmospheric advection influences the two regions differently during winter. The differential advective effects are much weaker in the other seasons. The Pacific Decadal Oscillation is the strongest correlator with interannual variability in the two regions, followed by the Arctic Oscillation and the El Niño/Southern Oscillation.Projected changes by the late 21st Century are qualitatively similar to the changes that have been ongoing over the past 60 years, although the rate of change increases modestly under mid-range forcing scenarios (e.g., the A1B scenario). The greatest warming is projected to occur farther north over the Arctic Ocean in response to sea ice loss. Precipitation is projected to increase by all models, although increases in evapotranspiration preclude conclusions about trends toward wetter or drier land surface conditions. A notable feature of the future climate simulations is a strong maximum of pressure decreases in the Bering Sea region, implying further advective changes.     

全球集装箱航运的空间组织网络

集装箱运输网络是经济全球化背景下物质要素资源在全球进行配置的主要承载体,而航运企业是航运网络的组织者;基于航运企业的组织行为,可以考察全球航运网络的基本格局与空间体系。本文选取全球主要的24家集装箱班轮公司和530个港口为研究样本,以集装箱船月度运营表为研究对象,构筑数理评价模型,剖析全球集装箱航运组织网络的空间格局和主要港口的集装箱组织能力,探讨了全球港口的运输联系格局和主要空间系统。研究表明:东亚和东南亚为重点组织区域,以此为核心构筑全球集装箱航运网络;全球港口的航线设置和航班组织及运输联系形成东亚、东南亚、西北欧和美东四大集聚区域,航运组织尚未形成全球性空间系统,但形成许多区域性系统,区域化明显。     

Holocene millennial-scale climate variations documented by multiple lake-level proxies in sediment cores from Hurleg Lake,Northwest China

Millennial-scale climate variability has not been well documented in arid northwest China due to the scarcity of high-resolution, well-dated paleoclimate records. Here we present multi-proxy records from sediment cores taken in freshwater Hurleg Lake on the northeastern Tibetan Plateau, which reveal millennial-scale lake-level and climate variations over the past 8,000 years. This high-elevation region is very sensitive to large-scale climate change, thus allowing us to better understand Holocene climate variations in East Asia. The lake-level record, derived from lithology, magnetic mineralogy, carbonate isotopes, ostracode shell isotopes and trace elements, X-ray fluorescence (XRF), and gray scale data, indicates a highly variable and generally dry climate from 7.8 to 1 ka (1 ka = 1,000 cal year BP), and a relatively stable and wet climate after 1 ka. Superimposed on this general trend, six dry intervals at 7.6–7.2 ka, 6.2–5.9 ka, 5.3–4.9 ka, 4.4–3.8 ka, 2.7–2.4 ka, and 1.7–1.1 ka were detected from the high-resolution carbonate content and XRF data. The generally dry climate between 7.8 and 1 ka was almost synchronous with the decrease of East Asian and Indian monsoon intensities shortly after 8 ka. The six dry intervals can be correlated with weak monsoon events recorded in the East Asia and Indian monsoon regions, as well as the North Atlantic cold events. Our data suggest that millennial-scale monsoon variations could cause highly variable climate conditions in arid northwest China during the Holocene. These millennial-scale climate variations may reflect changes in solar variation and/or changes in oceanic and atmospheric circulation.     

Flooding 1990s along the Yangtze River, has it concern of global warming?

1 IntroductionFloods occurring along the Yangtze River (Changjiang River) valley make up about 35.8 % of the floods over China[1]. Most noteworthily, a series of severe floods happened along the middle to lower Yangtze River and caused great damages during the past decade. The flood of 1991 afflicted 0.98 million hectares of farmland and resulted in 1,200 loss of life. Severe flood occurred again over this region in 1996. An extremely destructive flood emerged during the summer of 1998, wh…     

CONTRASTING TREE‐RING GROWTH RESPONSE OF PICEA ABIES TO CLIMATE VARIABILITY IN WESTERN AND EASTERN ESTONIA

Climatic variations and changes regulate arboreal growth. In Estonia, the tree‐ring growth variability of coniferous and deciduous trees has been linked with various climatic variables in different parts of the country. However, the dendroclimatic signals of Norway spruce (Picea abies (L.) H.Karst.) have not been explored across the region. Here we compare the growth variability of this species, growing under various site conditions in Estonia, with records of temperature, precipitation, and indices of the North Atlantic Oscillation over a period of 50 years (1956–2005). Western chronologies correlated positively and significantly (p<0.01) with early‐summer (June) precipitation, while eastern chronologies showed positive and significant (p<0.05) correlation with mid‐winter (January) precipitation. Moreover, the eastern chronologies correlated positively and significantly (p<0.05) with the North Atlantic Oscillation index in January. First, our results indicated that the previously established geobotanical division, rather than forest site types, most probably explains the spatial patterns in spruce growth variability. Second, our findings agreed with the late Quaternary pollen studies showing that the vigour of spruce is limited in the western forests by a combination of climatic (i.e. summer moisture) and edaphic factors. Third, our results complement those of previous investigations, suggesting that the impacts and threats the changing climate will pose on spruce may be different in western and eastern Estonia, with more severe effects envisaged in the western part of the region through drought‐induced physiological stress.     

The August 2007 Heat Wave in North Carolina: Meteorological Factors and Local Variability

August 2007 was an exceptionally warm month across North Carolina. Hundreds of daily maximum and daily high minimum temperature records, as well as numerous all-time temperature records, were either tied or broken during the month. At the same time, a drought of historic proportions overspread much of the Southeast United States. A critical aspect of the August 2007 heat wave was the observed variability in heat and humidity across the different geographic regions of North Carolina. The highest maximum temperatures occurred most frequently in the Piedmont and Sandhills regions, while minimum temperatures were exceptionally high along the coast. The broad-scale pattern of heat can be tied to adiabatic warming associated with subsidence downstream of a persistent upper-level ridge centered over the Mississippi River Valley. Regional to local variations in the heat and humidity across North Carolina are linked to upwind sensible heat fluxes associated with major soil moisture deficits, adiabatic warming connected with downsloping winds off the Appalachian Mountains, and the depth of the mixing layer. Along the coast, the pattern of heat and humidity was tied to the positioning of a mesoscale thermal trough and the presence and strength of the sea-breeze circulation.     

Spatiotemporal characteristics of seasonal precipitation and their relationships with ENSO in Central Asia during 1901–2013

The vulnerable ecosystem of the arid and semiarid region in Central Asia is sensitive to precipitation variations. Long-term changes of the seasonal precipitation can reveal the evolution rules of the precipitation climate. Therefore, in this study, the changes of the seasonal precipitation over Central Asia have been analyzed during the last century (1901–2013) based on the latest global monthly precipitation dataset Global Precipitation Climatology Centre (GPCC) Full Data Reanalysis Version 7, as well as their relations with El Niño- Southern Oscillation (ENSO). Results show that the precipitation in Central Asia is mainly concentrated in spring and summer seasons, especially in spring. For the whole study period, increasing trends were found in spring and winter, while decreasing trends were detected in summer and fall. Inter-annual signals with 3–7 years multi-periods were derived to explain the dominant components for seasonal precipitation variability. In terms of the dominant spatial pattern, Empirical orthogonal function (EOF) results show that the spatial distribution of EOF-1 mode in summer is different from those of the other seasons during 1901–2013. Moreover, significant ENSO-associated changes in precipitation are evident during the fall, winter, spring, and absent during summer. The lagged associations between ENSO and seasonal precipitation are also obtained in Central Asia. The ENSO-based composite analyses show that these water vapor fluxes of spring, fall and winter precipitation are mainly generated in Indian and North Atlantic Oceans during El Niño. The enhanced westerlies strengthen the western water vapor path for Central Asia, thereby causing a rainy winter.     

东南亚恐怖主义的时空演进及其网络关系

以全球恐怖主义数据库（GTD）的研究数据为基础,运用地学空间统计分析方法和社会网络分析方法,对2000－2018年东南亚发生的恐怖主义事件进行时空演变特征分析及其参与组织的社会网络关联解析,得出以下结论：1）东南亚恐怖主义发展态势呈现显著的阶段性波动增长,在空间上表现为明显的集聚性,由2000－2013年的两极集聚中心转变为2014－2018年的三级集聚中心。2）东南亚恐怖主义组织众多,恐怖组织类型复杂,各恐怖组织及独狼型恐怖主义之间通过情报、资源及人员交流等方式进行联系,形成了一个巨大的跨地区恐怖组织网络;以伊斯兰祈祷团（JI）为代表的东南亚恐怖组织在上个世纪90年代利用域外组织的支持建立了一个横跨多国、分工明确的4M活动网络,并利用此活动网络进行资金筹集、人员培训、策划活动等。3）东南亚恐怖主义迅速发展有其深层次原因,既有地区内部社会文化、政治环境和经济发展的影响,又有区域外恐怖主义势力的干预。     

基于水化学和同位素评价马莲河下游地下水补给河水的时空变化

准确评价地下水对河水的补给量是流域水资源量管理和合理利用的基础。在马莲河流域下游采集不同季节地表水和地下水样品75组,利用Cl^-、电导率（EC）和D、¹⁸O同位素多方法联合评价,识别了地下水补给河水的位置、补给量及其季节变化。结果表明：马莲河水EC和Cl^-质量浓度沿着流向均呈降低趋势,δD和δ¹⁸O值沿流向减小。雨季EC和Cl^-质量浓度最低,δD和δ¹⁸O值最高。地下水各组分浓度均低于河水,时空变化不明显。地下水单宽排泄量存在时空变异,上段和下段为地下水强排泄区,中段地下水排泄较弱,不同季节地下水排泄量占总排泄量的72.20%～95.07%。雨季地下水单宽排泄量显著降低,河水中基流比例由雨季前期的68.89%降至29.43%。整体上,地下水补给河水季节变化明显,而空间变化规律较为稳定。研究成果有利于深入认识河水和地下水的相互作用机制,并为当地水资源利用提供基础依据。     

Flooding 1990s along the Yangtze River, has it concern of global warming?

There were a series of severe floods along the middle to lower reaches of the Yangtze River (Changjiang River) in China during the 1990s. The extensive summer (June, July and August) precipitation is mostly responsible for the flooding. The summer rainfall in the 1980s and the 1990s is much higher than that in the previous 3 decades. The means for 1990-1999 is +87.62 mm above normal, marked the 1990s the wettest decade since the 1950s. Six stations with a time span of 1880-1999 are selected to establish century -long rainfall series. This series also shows that the 1990s is the wettest decade during the last 120 years. In the wettest 12 years, four occurred in the 1990s (1991,1996,1998 and 1999). Both global and China’s temperature show there is a relative lower air temperature during the 1960-1970s, and a rapid warming in the 1980-1990s. Comparisons of rainfall between 1960-1979 and 1980-1999 show there are dramatic changes. In the cold period 1960-1979, the summer rainfall along the Yangtze River is 3.8 % to 4.7 % below the normal, during the warm period 1980-1999, over 8.4 % to 18.2 % of summer rainfall occurs. Over the whole eastern China, the summer rainfall shows opposite spatial patterns from the 1960-1970s to 1980-1990s. The consistent trend toward more rainfall with global warming is also presented by the greenhouse scenario modeling. A millennial Drought/flood Index for the middle to lower reaches of the Yangtze River showed that although the surplus summer rainfall in the 1990s is the severest during the past 150 years, it is not outstanding in the context of past millennium. Power spectra of the Drought/flood Index show significant interdecadal periods at 33.3 and 11.8 years. Thus, both the natural inter-decadal variations and the global warming may play important roles in the frequent floods witnessed during the last two decades.