长株潭地区20世纪50年代以来极端气候事件变化特征

基于长沙、株洲、湘潭3个气象站1951-2006年期间的气温、降水资料,分析了长株潭地区极端高温、极端低温、暴雨和干旱事件的变化特征.结果表明:该地区极端高温、低温和干旱事件变化总体皆呈显著下降趋势;暴雨频次略有上升,但不显著;基于Morlet函数的小波分析显示,本区50年代以来的极端气候事件表现为较明显的3～6a周期和较弱的8～14a周期.     

滴哨沟湾地层沉积特征记录的毛乌素沙漠变迁

毛乌素沙漠的盛衰变化明显地受到全球变化特别是东亚夏季风变化的影响。根据毛乌素沙漠东南缘萨拉乌苏河流域滴哨沟湾地层沉积物的物质组成、粒度参数等,结合孢粉研究结果,将沙漠演化过程划分为若干阶段：中更新世晚期沙漠萎缩期,气候温暖半干旱-半湿润,沙漠缩小,为森林草原或灌丛草原;中更新世晚期沙漠稳定期,气候在寒冷干旱-半干旱间波动频繁,自然景观在荒漠、荒漠草原与干草原间变化,并有河流和小湖存在;晚更新世早期沙漠固定期,气候温暖半湿润至半干旱,期间自然景观经历了森林草原、灌丛草原、草原、荒漠草原多种变化;晚更新世晚期沙漠扩张期,气候干旱寒冷,自然景观以荒漠和荒漠草原为主,同时也有草原乃至灌丛草原出现;全新世沙漠频繁变化期,气候变化频繁,沙漠出现多次盛衰变化,自然景观在荒漠、荒漠草原、草原、疏林草原间变化。     

宁夏冬季气温的变化及同期500hPa环流特征量的变化特征

通过近40多年来宁夏冬季气温的变化进行了研究,结果表明:宁夏冬季气温总趋势是变暖的,冬季平均气温在1985年前后发生突变,突变后升温最明显的是中部干旱带;宁夏冬季气候变暖与大区域有不同之处,1967-1990年宁夏冬季升温过程,最低气温是主要的,但1990年以后宁夏冬季的变暖,并不完全是由于最低气温的变暖而形成,最高气温的变暖也是20世纪90年代以来宁夏冬季气候变暖的重要特征;宁夏极端气温变化具有明显阶段性特征,80年代末期以后极端最低气温的变率明显增大;冬季北半球500 hpa极涡面积、亚洲西风环流指数、东亚大槽位置、西太平洋副热带高压强度与宁夏冬季平均气温有较为一致的年代际气候特征;小波分析发现,以上环流特征量与宁夏冬季平均气温存在相同的4年左右的主周期变化,且在时、频域上有较为一致的对应关系。     

黄渤海海岸季节性风沙气候环境

分析了黄渤海海岸气候形成因素和影响风沙活动的各种气候要素的季节性变化特征，指出冬、春季研究区受东亚大陆气团的影响，形成了干旱、多风的风沙气候环境，尤其是渤海海岸地区冬、春季气候条件与我国内陆沙漠区和严重沙漠化地区相似，也存在风沙灾害的威胁。     

东北气候和生态过渡区近50年来降水和温度概率分布特征变化

文章从中国160个站的观测资料中选取位于东北气候和生态过渡区内9个测站的冬、夏季降水和温度资料,分析该地区近50年来冬夏季降水和温度的年际变化及其概率分布特征,结果表明,东北气候和生态过渡区的冬夏季降水和温度有明显的年代际变化特征,在不同的年代际变化阶段,降水和温度的总体概率分布特征差异较大,这种概率分布形式的差异与高温、干旱等极端天气气候事件的频繁发生具有密切关系。20世纪80年代以来降水处于平均值减小的总体分布中,温度则处于平均值增加的总体分布中,因此该地区冬季发生暖冬和少雨(雪)的机会增大,夏季出现严重干旱和高温的可能性增大。     

我国内陆沙漠与海岸沙丘石英颗粒表面结构的对比研究

本文通过扫描电镜分析，对我国内陆沙漠与海岸抄丘石英颗粒表面结构进行了对比研究。研究认为，无论是内陆沙漠砂或海岸沙丘砂，其石英颗粒都具有较好的磨圆度，表面有碟形坑、麻坑及ＳｉＯ＿２沉淀物等代表风成环境的典型特征；此外，还叠加有代表原生沙物质来源于水下环境的Ｖ型撞击坑、撞击沟等痕迹。然而，受环境尤其是气候影响，其表面结构特征仍有差异，表现在内陆干旱区大陆性气候的沙漠砂的风成机械作用和化学沉淀作用，都要比沿海湿润季风性气候的海岸沙丘砂强烈；但海岸沙丘砂的化学溶蚀作用却比内陆沙漠砂要明显。同属海岸抄丘环境，其石英颗粒表面结构特征表现为北方温带海岸沙丘砂的机械作用痕迹强；而南方热带海岸沙丘砂的化学作用痕迹发育，但机械作用痕迹并非少见，仍然十分明显。     

夏季不同天气背景条件下黑河中游不同下垫面的辐射特征

 利用2005年“绿洲系统能量水分循环观测实验”（JTEX）获得的资料分析了夏季晴天和阴天西北干旱区金塔绿洲不同下垫面的辐射收支特征。结果表明:由于下垫面的水热特性不同,绿洲与沙漠、戈壁的辐射特征有很大差异,而沙漠和戈壁的差异则较小。相同天气背景条件下,不同下垫面的向下辐射基本一致,绿洲的向上辐射最小,净辐射最大。地表辐射特征会随天气状况有较大变化。     

宁夏地表湿润状况及极端干湿事件演变规律

利用宁夏1961—2004年月平均气温、月降水量资料,计算了地表湿润指数,以此为基础对宁夏地表湿润状况及极端干湿事件的分布特征进行了较为深入的研究。结果表明:近40多年来,宁夏大致经历了冷湿期、冷干期、暖干期;自20世纪60年代以来,宁夏年极端干旱频率有增加的趋势,极端湿年高频区逐渐缩小; 80年代以来,宁夏极端干旱年事件高频区明显扩大;不同气候型态下,极端干湿事件频率具有明显差异,冷干期极端干旱事件最多,极端湿润事件最少,冷湿期极端干旱频率最小,极端湿润频率最大。     

试论未来极端气候事件发展趋势的不确定性

极端气候事件是在一定时间尺度上发生的不同于气候系统平均状态的气候突变.早第三纪的最热事件（PETM）,第四纪中国黄土高原古土壤S4、S5记录的暖湿事件,砂黄土L9、L15记录的干冷事件等都是在轨道时间尺度上发生的极端气候事件.末次冰消期的YD冷事件、全新世9次冷事件是在千—百年尺度上发生的极端气候事件.这些极端气候事件出现于地球气候系统不同的冷暖背景下,它们的成因机制和表现形式有很多不确定性.20世纪以来发生的干旱、洪水、飓风、雪灾、沙尘暴等极端气候事件,无法用持续增加的温室气体的变化来解释.关于极端气候事件发生频率和强度随＂全球变暖＂而增加的结论也存在一定程度的不确定性.因此,简单地将现代极端气候事件统统归因于＂气候变暖＂既不科学也不合理.深入研究各个时间尺度上发生的极端气候事件的波动性、周期性和不确定性特征,有助于科学预测未来气候变化背景下极端气候事件的发展趋势.     

基于日SPEI的近55 a西南地区极端干旱事件时空演变特征

利用1960~2014年中国西南地区141个气象台站的逐日气象资料,引入一个新的干旱指数——逐日标准化降水蒸散指数（日SPEI）,对极端干旱事件的年代际、年际、季节内变化及持续性特征进行了分析,结果表明：空间上,近55 a西南春季和年极端干旱程度呈一致的减弱趋势,重庆、四川与贵州的交界处及四川西北部极端干旱程度明显缓解,而夏、秋两季极端干旱表现出增强的趋势并有一定的区域性特征。时间上,春季和全年极端干旱频率、强度和持续天数逐渐减少,春季极端干旱的减弱程度较全年明显;夏、秋两季极端干旱频率、强度和持续天数呈增加趋势,夏季极端干旱的加重趋势比秋季明显。从极端干旱事件的持续性来看,20世纪60年代和21世纪初（2000~2014年）西南遭受的极端干旱最严重,持续期达60 d以上的站点分别占到站点总数的60%和73%。     

Variations of monsoonal precipitation over the last 16,000 years in the eastern Nanling Mountains,South China

A 350-cm-long sediment core was recovered from Dahu Swamp in the eastern Nanling Mountains in south China for paleoclimatic investigation. Twelve ¹⁴C dates determined on organic-rich bulk samples establish a chronological sequence for this core and yield a bottom age of ~16,000 cal years BP. Multiproxies including dry bulk density, magnetic susceptibility, organic carbon isotope, median grain size, silt-size fraction and total organic matter content were used to study variations of precipitation in relation to the East Asian monsoon. The core sediments are characterized by shifts between the lacustrine sediments and marshy sediments, implying hydrological variations between expansion and shrinkage of the water body in the swamp, and suggesting relatively wetter and drier conditions, respectively. Two relatively wetter episodes lasting from ~15,000 to 14,000 cal years BP and from ~13,500 to 12,800 cal years BP were revealed, possibly corresponding to the Bølling and the Allerød warming events, and three relatively drier phases occurred between ~16,000 and 15,000 cal years BP, between ~14,000 and 13,500 cal years BP and between ~12,800 and 11,500 cal years BP. The three events synchronize with the Oldest Dryas, the Older Dryas and the Younger Dryas cooling events, respectively. A distinctly humid period lasted from ~10,000 to 6,000 cal years BP in the early- and mid- Holocene was interpreted as the Holocene Optimum period. Several short dry events were revealed, including the most pronounced one at ~8,100 cal years BP that coincides with the “8,200 year” cooling event. Multiproxies indicate an evidently dry climate prevailing in the mid-Holocene (from ~6,000 to 3,000 cal years BP), reflecting a weakening of the East Asian summer monsoon. The general trend of Holocene climate shows agreement with the 25°N summer solar insolation, suggesting that the orbitally induced insolation have played a key role in the Holocene climate in south China.     

毛乌素沙地南缘全新世自然环境

根据毛乌素沙地南縁柳树湾剖面的孢粉分析,结合岩性、¹⁴C测定等资料,揭示该地全新世植物群落的演替,讨论自然环境的变迁。     

Climatic Change and Desert Vegetation Distribution: Assessing Thirty Years of Change in Southern Nevada's Mojave Desert

A major theme in physical geography and biogeography is understanding how vegetation changes across geographic gradients during climate change. We assess shifts in distributions of fifteen Mojave Desert plant species based on a 2008 resurvey of 103 vegetation transects that were established in 1979. We model changes in species distributions using Maximum Entropy (Maxent) with environmental and climate variables to predict probability of species’ occurrences. Climate during the ten-year period preceding the 2008 vegetation survey was 1.5°C warmer and 3 cm per year of precipitation drier than the ten years preceding 1979. Species inhabiting the highest elevations and strongly correlated with precipitation displayed areal reductions from 1979 through 2008.     

土地利用和气候变化对区域净初级生产力影响

1IntroductionThe global change caused by the continuous increasing concentration of atmospheric greenhouse gases has threatened the existence of human beings, and the importance of carbon dioxide emissions as a major environmental issue of international concern has grown substantially in the world (IPCC, 2000). At the same time, the Kyoto Protocol, the first and only realistic plan for achieving a worldwide reduction in greenhouse gas emissions, has been passed. Since there are many uncertai…     

SIMULATION OF CLIMATE CHANGE IMPACTS ON WATER BALANCES IN THE CENTRAL UNITED STATES

Climate change is simulated using a stochastic weather generator model forced to simulate an increase in temperature of 2.5°C and in precipitation of 10 percent over a 50-year period. Output from the climate simulations are input into a water balance model. Simulations are performed for five climate divisions along a transect from semiarid western Kansas to humid eastern Missouri. Results show that even under a scenario of increasing precipitation all divisions suffer decreased summer soil moisture, with the driest divisions in Kansas suffering the largest decrease. Total runoff decreases in all divisions with the largest percentage decrease occurring in central Kansas. The largest absolute decreases in total runoff, however, occur in the humid climates. The increase in the water deficit in the drier divisions is more than twice that of the humid divisions. When attempting to detect the climate change signal in hydroclimatic variables, temperature and potential evapotranspiration are the most sensitive while annual runoff is not useful as a potential indicator of change.     

新疆克里雅河源流区径流变化与气候因子关系的非线性分析

利用克里雅河源流区兰干站1957～2009年的年径流量、气温和降水量实测数据,借助小波分析和R/S分析等方法探讨了径流量、气温和降水量的变化趋势及多时间尺度相关性。结果表明:(1)年径流量与气温和降水量存在明显的正相关关系并皆呈增加趋势,结合R/S分析,这种增加趋势在未来的50a仍将可能持续。(2)研究区年径流量、气温和降水量均存在9年的年际变化周期,而在年代际上由于气温和降水量周期性不同致使径流量的周期为15年。另外,三者在未来的20年存在不同的周期性突变。(3)克里雅河源流区径流量与气温和降水量存在显著的非线性相关关系。年径流量的变化是气温和降水量综合作用的结果。     

西沙群岛和涠洲岛气候变化特征 及其与近岸陆地的对比

采用1959―2014年中国西沙站和涠洲岛站及其临近陆地台站的基本气象观测资料,分析了2个海岛的气候变化特征及其与近岸陆地的差异。结果表明：1）近56年西沙和涠洲岛及近岸陆地气温变化均呈上升趋势,西沙增暖速率（0.19℃/10 a）大于涠洲岛（0.104℃/10 a）。显著的差异出现在近10年,西沙持续增暖（0.38℃/10 a）,而涠洲岛气温却呈下降趋势（-0.48℃/10 a）。从季节变化上,2个海岛都有春季越来越暖、冬季越来越冷的趋势。与周围陆地的气温相比,2个海岛的气温均高于近海陆地,但增温速率却小于近岸陆地。2）分析近56年降水量的变化,发现海岛降水量、降水强度和降水天数均小于陆地。受冬、夏季风转换的控制,海岛及近岸陆地有旱季、雨季的划分,且近半个世纪以来降水量波动大、变化趋势不显著,但伴随降水天数的减少,降水强度呈显著增长趋势。对比2个海岛近10年的降水变化特征,发现西沙站的旱季有越来越旱的趋势,涠洲岛及近岸陆地无论旱季、雨季降水量都有增加的趋势,表现为湿润化的趋势。     

Summer Moisture Variability in East Central Sweden Since the Mid-Eighteenth Century Recorded in Tree Rings

To make predictions of future climate it is necessary to understand the past climate—temperature as well as precipitation. While a wealth of temperature proxies exist from northern latitudes, there is still a lack of information about past precipitation variability. Here we present a 300‐year‐long tree‐ring width chronology from xeric‐site Scots pines (Pinus sylvestris L.) in Tyresta National Park, east central Sweden. Tree‐ring widths were compared to the long observed temperature and precipitation records from Stockholm during 1786–2000. Analyses of the climate/growth relationship showed that, in general, May–June precipitation had a dominating influence on pine growth. However, during dry periods, negative responses to June–July temperature were stronger, especially evident in the late nineteenth century. Periods of below‐average growth were associated with dry conditions in May–June, but occasionally periods of wet and cool summers also produced narrow rings. Periods of above‐average growth were linked to wet, but sporadically also cool and dry, early summers. The years between 1815 and 1833 appear to be particularly dry in the 300‐year context. Since growth anomalies are found in other Swedish drought‐sensitive tree‐ring chronologies during this period, it is likely that this dry period had a regional extent. This is the first tree‐ring chronology from southern Sweden that provides multi‐century information of past summer drought and moisture variability with high resolution and the study will add important information regarding past climate variability in southern Sweden.     

南极洲维斯特福尔德丘陵与菲尔德斯半岛冰缘地貌的比较研究

东南极大陆沿岸的维斯特福尔德丘陵(68°22'～68°40'S,77°55'～78°30'E)和西南极乔治王岛南端的菲尔德斯半岛(62°08'～62°20'S,58°45'～58°58'W)的气候条件不同。前者属于极地大陆性气候,气温低,冬季严寒,干燥、风大,夏季较短;后者属于极地海洋性气候,气温不很低,湿润、风小,夏季较长。因此,两地的冰缘地貌的组合类型及其发育过程存在明显的差异。前者冰缘地貌单一,发展速度较慢;后者冰缘地貌复杂多样,发展速度较快。 本文根据实地观测资料,对极地大陆型和极地海洋型两类冰缘地貌作一些比较,并且提出,年冻融日数是决定冰缘作用强弱的最重要指标。     

Impacts of future climate change on agroclimatic resources in Northeast China

In this study, the spatial distribution and changing trends of agricultural heat and precipitation resources in Northeast China were analyzed to explore the impacts of future climate changes on agroclimatic resources in the region. This research is based on the output meteorological data from the regional climate model system for Northeast China from 2005 to 2099, under low and high radiative forcing scenarios RCP4.5 (low emission scenario) and RCP8.5 (high emission scenario) as proposed in IPCC AR5. Model outputs under the baseline scenario, and RCP4.5 and RCP8.5 scenarios were assimilated with observed data from 91 meteorological stations in Northeast China from 1961 to 2010 to perform the analyses. The results indicate that: (1) The spatial distribution of temperature decreases from south to north, and the temperature is projected to increase in all regions, especially under a high emission scenario. The average annual temperature under the baseline scenario is 7.70°C, and the average annual temperatures under RCP4.5 and RCP8.5 are 9.67°C and 10.66°C, respectively. Other agricultural heat resources change in accordance with temperature changes. Specifically, the first day with temperatures ≥10°C arrives 3 to 4 d earlier, the first frost date is delayed by 2 to 6 d, and the duration of the growing season is lengthened by 4 to 10 d, and the accumulated temperature increases by 400 to 700°C·d. Water resources exhibit slight but not significant increases. (2) While the historical temperature increase rate is 0.35°C/10a, the rate of future temperature increase is the highest under the RCP8.5 scenario at 0.48°C/10a, compared to 0.19°C/10a under the RCP4.5 scenario. In the later part of this century, the trend of temperature increase is significantly faster under the RCP8.5 scenario than under the RCP4.5 scenario, with faster increases in the northern region. Other agricultural heat resources exhibit similar trends as temperature, but with different specific spatial distributions. Precipitation in the growing season generally shows an increasing but insignificant trend in the future, with relatively large yearly fluctuations. Precipitation in the eastern region is projected to increase, while a decrease is expected in the western region. The future climate in Northeast China will change towards higher temperature and humidity. The heat resource will increase globally, however its disparity with the change in precipitation may negatively affect agricultural activities.