松花江区气象水文干旱演变特征

采用标准化降水蒸散指数和径流干旱指数分析了1961~2010年研究区水文干旱和气象干旱时空演变特征,并探讨了水文干旱与气象干旱的关系。结果表明：① 1961~2010年松花江区呈总体干旱化且又有明显时段性的特征,其中1967~1983年和1996~2010年气象干旱频发、覆盖范围广、持续时间长且强度大;其它时段气象干旱少有发生。其次,气象干旱空间分布差异明显,东部的平均干旱频次和强度都大于西部地区,中部（嫩江流域中下游）平均干旱持续时间最长;但在嫩江流域和黑龙江上游地区干旱略有减弱趋势。② 松花江流域和挠力河流域水文干旱呈加剧的趋势,尤其是近15 a干旱化趋势明显;挠力河流域干旱频发、强度大且持续时间很长。松花江流域水文干旱程度弱于挠力河流域,但极端水文干旱事件频发。 ③ 松花江区气象干旱与水文干旱密切相关,嫩江流域水文干旱滞后于气象干旱2个月,而第二松花江流域和松花江流域水文干旱滞后于气象干旱3个月;挠力河流域水文干旱与气象干旱无明显的时滞相关性。     

1961—2020年青海高原日照时数时空变化特征

太阳辐射是地球系统的主要能源,与人类的生活密切相关。通过选取青海高原50个气象观测站点1961—2020年逐月日照时数数据,分析了青海高原整体、不同纬度地区、不同海拔高度地区日照时数时空变化特征。结果表明：（1）1961—2020年青海高原年日照时数呈显著降低趋势,且在2004年发生突变降低。从空间分布来看,除南部个别站点日照时数持平或略微增加外,其余地区年日照时数均呈显著降低趋势,其中柴达木地区和东部农业区降低趋势最显著。（2）青海高原高纬度地区年日照时数降低趋势显著大于低纬度地区。春季不同纬度地区日照时数变化趋势均较小,夏季和冬季纬度相对较高地区日照时数减少趋势显著大于纬度较低地区,秋季纬度较低和纬度较高地区日照时数减少趋势显著大于中纬度地区。（3）青海高原海拔相对较低地区年日照时数降低趋势显著大于海拔相对较高地区。春季不同海拔高度地区日照时数变化趋势均较小,基本持平或略微减少,夏季和冬季海拔相对较低地区日照时数减少趋势显著大于海拔较高地区,秋季不同海拔高度日照时数均呈减少趋势,但是减少趋势显著性状况差异较大。     

ENSO事件与山西气候的关系

通过搜集和整理1955-2008年大同、河曲、原平、太原、阳泉、介休、离石、长治、临汾、运城等地的气象资料,分析了山西的降水量、气温与ENSO事件的关系,研究了ENSO事件对山西气候的影响。结果表明,1955-2008年ENSO事件呈现出起伏波动的特点,1980年以后波动趋势更为剧烈;大致可分为两个阶段:1955-1980年为第1阶段,ENSO冷事件的频次略高于暖事件,但强度更大;1981-2008年为第2阶段,ENSO暖事件的频次和强度均高于冷事件。ENSO事件对山西降水量的影响表现十分明显,ENSO暖事件当年降水量明显偏低,次年降水量明显增加或达到最高趋势明显。ENSO冷事件年全省降水量均明显增加。ENSO事件对山西气温的影响也十分显著,ENSO暖事件年大多表现为气温偏高或升温,ENSO冷事件年一般表现为气温偏低或降温。     

1960-2020年辽宁沙尘强度特征

基于1960-2020年辽宁56个气象站地面观测资料,计算沙尘强度指数,应用回归方程、M-K非参数检验和相关分析等得到辽宁沙尘天气的年际分布特征.结果表明:影响辽宁的主要沙尘天气是扬沙,其次是浮尘、沙尘暴.影响辽宁东南部和南部的主要沙尘天气是浮尘,影响其他地区的主要沙尘天气是扬沙.辽宁沙尘强度呈显著减弱趋势,2010年...     

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%。     

祁连山讨赖河流域1957—2012年极端气候变化

全球气候变化背景下,极端气候事件发生的频率逐年增大,由此引发的气象灾害事件也随之增加。鉴此,本文利用祁连山讨赖河流域1957—2012年的气象观测资料,对该流域23个极端气候指数的时空变化特征做了研究。结果表明：（1）极端气温升高趋势明显,夜间和白天极端低温日数显著减少,极端气温昼指数显著增大;气温日较差变化幅度很小,霜冻日数显著减少,生长季长度明显加长,冰冻日数2000年后增加;夜指数增大幅度大于昼指数,秋、冬季极端气温升高幅度大于春、夏季。（2）极端降水指数增大趋势明显,雨日降水总量、连续五日降水总量和中雨天数均展现出增大态势,反映出连续降水事件的增加;极端降水量事件增大显著,但雨日降水强度变化不大;除最多连续无降水日数外,极端降水日数指数展现出增大趋势;降水日数夏、秋季节分配趋向均匀化;降水量的增加主要是单次降水时间持续加长和中雨日数增加的贡献;高海拔区极端降水事件发生的频次较大。     

The influence of micro-climate, snow cover, and soil moisture on ecosystem functioning in high mountains

The dynamics of water and energy fluxes in the high mountains of central Norway was studied along micro-spatial topographic gradients in different altitudes and regions of the Scandes. Landscape ecological processes like snow accumulation during winter, snow melting, evaporation, percolation, soil moisture variability and temperature variations were quantified. Combining spatio-temporal data on physical environment functioning and vegeta-tion patterns resulted in a process-oriented characterisation of high mountain ecosystems. Extensive data from long-term measurements were synthesised illustrating the influence of micro-climate, snow cover, and soil moisture on high mountain ecosystem functioning. The results reveal that the micro-climatic impact on the vegetation is predominantly determined by snow cover overlaying soil moisture gradients. Water only becomes superior where near-surface water saturation and flooding occur. A lack of soil moisture availability was not found during any time of the year even under driest site conditions. Contrasting literature, the Norwegian mountain vegetation was found to be interpreted by environmental variable con-stellations excluding drought stress.     

小气候、雪盖及土壤湿度对高山生态系统功能的影响(英文)

1 Introduction High mountain landscapes above the tree-line are often regarded as close to nature, although human impact has obviously changed the environment, partly exceeding its carrying capac- ity (L?ffler, 2000). Due to their fragility regarding expe…     

利用MODIS/EVI数据分析干旱对西南地区植被的影响(英文)

2009年9月至2010年3月我国西南地区出现了有气象记录以来最严重的干旱,给当地的自然环境和生产、生活带来严重影响。本文利用多年MODIS/EVI数据求取距平植被指数来反映干旱对西南地区植被的影响。在此基础上,分析了西南地区植被受旱的时空格局及其可能影响因素。结果表明,我国西南地区植被受干旱影响的范围很大,超过地区总面积的50%,植被受旱程度时空差异显著。这种显著的差异除了受降水等气象因素影响外,还与不同植被类型对干旱的响应差异有很大关系。在西南地区三种主要的植被类型中,作物是最易受干旱影响的植被类型,草地次之,林地的抗旱能力最强。此外,植被干旱的空间分布与气象干旱也存在很大的差异,进一步证明了降水以外的其他因素对干旱程度的调节作用。研究证明与气象干旱指数相比,植被指数更能反映干旱的实际情况。但在使用植被指数衡量干旱影响时也要考虑到植被指数本身的局限性。     

小气候、雪盖及土壤湿度对高山生态系统功能的影响

1 Introduction High mountain landscapes above the tree-line are often regarded as close to nature, although human impact has obviously changed the environment, partly exceeding its carrying capac- ity (L?ffler, 2000). Due to their fragility regarding expected environmental changes and an increasing land use pressure in many regions, high mountain landscapes recently became a major focus within the discussion on a sustainable development in a worldwide (Messerli and Ives, 1997), and regional p…     

Snow accumulation distribution on Spitsbergen, Svalbard, in 1997

A survey of the regional snow accumulation variability on Spitsbergen, Svalbard, was carried out during three field campaigns in May 1997. The survey was carried out along three transects from west-to-east approcimately at the following latitudes: 77°30', 78° and 78°50'degrees north. The altitudes span from sea level to 1000 metres elevation. Snow depth was measured with two different ground-penetrating radar systems, PulsEKKO (450 MHz) and GSSI SIR System-2 (500 MHz), pulled behind snow machines. Snow characteristics such as snow temperature, snow density and stratigraphy were measured in snow pits in nine areas, three along each transect. Our data suggest the following: (1)the accumulation-elevation gradients vary from 3 mm/100 m in the northeast to 237 mm/100 min the central-south with an average value of 104 mm/100m for all measurements: (2)snow accumulation was 38 to 49% higher at the eastern coast than at the western coast; (3) a clear minimum in accumulation (or continental climate) is seen for the central (inland) locations in the middle and northern transects while no such minimum exists along the southern transect; (4) a south-to-north gradient produces 55% and 40% less snow accumulation at the northern locations compared to the southern locations at the western and eastern coasts, respectively. These drops in winter snow accumulation occur over a distance of less than 200 km.     

Change in summer daily precipitation and its relation with air temperature in Northwest China during 1957–2016

On the basis of the summer daily-precipitation meteorological data collected from weather stations across Northwest China from 1957 to 2016, this study evaluated the trends in 12-daily precipitation indices in the summer season and their relations with air temperature. Precipitation-event intensity, which was averaged over the total study area, increased in recent decades although the total precipitation continuously decreased. In particular, intensity generally decreased in the northern and eastern parts and increased in the southern and western parts of the study area. None of the 12 precipitation indices was significantly correlated with temperature in Xinjiang; R95 N(number of events with precipitation greater than the long-term95 th percentile), RX1 day(greatest 1-day total precipitation), PI(simple daily intensity), and R10(number of heavy-precipitation days) were significantly and positively correlated with temperature in Qinghai–Gansu. However, low correlation coefficients were observed. In the Loess Plateau, P(total precipitation), WS(maximum number of consecutive wet days),R95 N, and WD(number of wet days) were significantly and negatively correlated with temperature, whereas Gini(gini concentration index) and DS(maximum number of consecutive dry days) were significantly and positively correlated with temperature. Results of the study suggested that climate shift was evident in terms of daily precipitation, and the study area faced new challenges involving precipitation-event intensity increasing in the southwestern part and unevenly dispersing in the northwest.     

民勤沙井子地区降水特征及干旱周期分析

利用民勤治沙综合试验站３４年（１９６１～１９９４年）降水的观测资料，对沙井子降水量、降水日数及其季节分配、降水强度、降水变率及降水保证率进行了统计分析，并采用降水变率和湿润指数（ＭＩ），应用最大熵谱方法（ＭＥＭ）对该区的干旱状况作出了周期分析     

中国近46年来冬半年日降水变化特征分析

中国总体冬半年降水总量、日降水强度以及强降水日数都有不同程度的增加趋势。西北地区的变化相对显著,其平均降水量、降水日数及日降水强度都呈增加趋势,特别是20世纪80年代后期发生跃变。华北和中部地区降水总量趋于减少。南方3区多为增加趋势,其中东南和华南与冬季风及欧亚遥相关型有显著的负相关关系,而西南地区日降水参数则与温度和北极涛动指数显著相关。东北地区降水指标没有明显的一致趋势。     

Younger Dryas Glaciation in Söderåsen, South Sweden: An Analysis of Meteorologic and Topographic Controls

In Söderåsen, South Sweden, various geomorphological investigations indicate that small, local glaciers were initiated at very low altitudes within the Skäralid rock canyon during the Younger Dryas period. Wind polish on boulders indicates that this period was characterised by easterly winds and drifting snow. Some new field observations are presented and the Söderåsen Younger Dryas reglaciation hypothesis is tested by means of empirical knowledge on glacier equilibrium line climate and an analytic geographical information system (GIS) experiment. The GIS analysis demonstrates that the deeply incised rock canyon represents a pronounced radiation shelter, while the empirical analysis emphasises the importance of strong snow drift from the east during the winter. Together, the two analyses indicate that the inferred Söderåsen Younger Dryas reglaciation is possible from a palaeoclimatic point of view, although conditions for glaciation may have been marginal to those of rock glacier initiation.     

库姆塔格沙漠周边地区极端降水的时空变化特征

根据中国气象局信息中心提供的库姆塔格沙漠周边地区20个气象站1960-2014年逐日降水量资料,分析了库姆塔格沙漠周边地区1960-2014年极端降水的时空变化特征。结果表明：（1）库姆塔格沙漠周边地区极端降水主要集中在夏季且存在很大的地域性差异。（2）1960-2014年库姆塔格沙漠周边地区极端降水事件、年大雨频次、年大降水事件降水量和年降水量显著增加。（3）库姆塔格沙漠周边地区西部极端降水主要由频数很少的暴雨贡献,而东部极端降水则由暴雨和大雨共同贡献。（4）库姆塔格沙漠周边地区极端降水指数在夏季和年尺度的空间分布相似,且强降水指数在年和夏季尺度的空间分布均呈“鞍型场”型。     

Modelling Transient Ground Surface Temperatures of Past Rockfall Events: Towards a Better Understanding of Failure Mechanisms in Changing Periglacial Environments

Despite the rising interest in mountain permafrost due to climatic changes and a noticed increase of registered rockfall events in the European Alps and other mountain ranges, little is known about transient thermal conditions in the detachment areas of rockfalls. Temperature conditions prior to the rockfall events of 144 past events in the European Alps were modelled with a physically based ground temperature model. To minimise the impact that uncertainty has on interpretations, only relative values were used, that is, percentiles obtained from cumulative distribution functions of the modelled ground surface temperatures from the beginning of the meteorological measurement series up to the event dates. Our results suggest that small and mid‐sized rockfalls (volumes up to 100 000 m³) from high elevation occurred mainly during short‐term periods of unusually high temperatures. This was neither found to be a result of the seasonal distribution (most analysed events in higher elevations occurred from July to September) nor of the longer‐term temporal distribution (most analysed events occurred after 2000) only. Plausible explanations are either a destabilisation related to advective thaw or failure due to stress redistribution caused by large temperature variations. Large deep‐seated rock slope failures (≥100 000 m³) in high elevation occurred all year round.     

秦岭太白山气温直减率时空差异性研究

在评估山地生态系统对气候变化响应的过程中,作为气温要素的重要输入参数,气温直减率（γ）的精确性直接影响到相关科研工作的真实性和可靠性。本文基于秦岭主峰太白山（3771.2 m）11个分布于南北坡和不同海拔的标准气象站点2013-2015年连续3年实测日均温资料和25 m×25 m空间分辨率的DEM数据,研究了太白山气温直减率在不同时间尺度上的变化规律及不同坡向上的空间分布特征。结果表明：① 2013-2015年太白山年均γ北坡均大于南坡,北坡为0.513 ℃/100m,南坡为0.499 ℃/100m;北坡年均γ随海拔变化表现出一定的差异性,而南坡相对稳定。② 年内γ在不同时间尺度上均存在明显差异,且南北坡变化趋势不一致。在季尺度上,γ最大值北坡为夏季,为0.619 ℃/100m,而南坡最大出现在春季,为0.546 ℃/100m,最小值均为冬季,南北坡分别为0.449 ℃/100m和0.390 ℃/100m;春季和夏季,北坡γ均大于南坡,而冬季相反,北坡小于南坡,秋季几乎无差异。在月尺度上,气温相对高的月份γ亦较高,北坡γ变化幅度大于南坡;年始和年末（11-12月、1-2月）北坡γ小于南坡,而5-9月北坡大于南坡,且南北坡γ相差较大。③ 经数据可信度分析,所获得的γ可较为客观地反映太白山气温随海拔变化的规律性,将为山地气温空间分布规律及其生态系统响应等定量研究提供理论基础。     

Spatio-temporal Characteristics of the Extreme Climate Events and Their Potential Effects on Crop Yield in Ethiopia

Extreme climate events exhibit an increasing spatio-temporal trend globally, and the increasing intensity and frequency may have severe impacts on the human society and natural ecosystems. This study analyzed the extreme temperature and precipitation variability from 1956 to 2016, and evaluated their potential effects on crop yield in Ethiopia. Relative extreme temperature indices exhibited a decreasing trend with low-temperature events, but a significantly upward trend with extreme high temperature events. The frequency of annual warm nights increased to a greater degree than that of cold days. The total annual wet-day precipitation decreased significantly at a rate of -46 mm/decade. Further, the succession of dry days gradually increased by 5.6 day/decade, while an opposite trend of wet days was found with a decline of 1.4 day/ decade. The correlation between annual precipitation and crop production was 0.422, indicating that extreme precipitation indices may have higher explanatory power than extreme temperature indices in the crop yield variations. Moreover, the extreme climate changes have induced significant adverse impacts on crops yield particularly in Ethiopia where no proper adaptation measures have been implemented.     

敦煌和酒泉夏季晴天和阴天边界层气象要素特征分析

利用国家重点基础研究发展规划项目《中国西北干旱区陆-气相互作用观测试验》2000年加强观测期(2000年5月29日～6月9日)敦煌探空观测资料和国家自然科学基金重点项目《绿洲系统能量与水分循环过程观测与数值研究》2004年加强观测期(2004年6月1日～7月16日)酒泉探空观测资料,分析了敦煌和酒泉地区夏季典型晴天和阴天天气下有关气象要素如风、温、湿的时空分布和变化特征,得到了以下结论:夏季,敦煌和酒泉地区大气边界层的东西分量风速(切变)晴天比阴天大;南北分量风速(切变)阴天比晴天大;东西分量风速(切变)比南北分量风速(切变)大。敦煌地区夏季晴天和阴天的风速比酒泉地区的大,但风速切变酒泉地区的要比敦煌地区的大。两地白天(晚上)的对流(稳定)边界层特征在晴天和阴天均很明显;阴天稳定边界层厚度和对流边界层的高度较晴天时的都低。比湿夜间比白天的大,阴天比晴天的大;在敦煌地区和酒泉地区都出现了逆湿现象;强逆湿主要出现在夜间,白天虽然也出现逆湿,但强度普遍较弱。