中国近50a气候变化复杂性分析

分析了我国气温和降水量变化的兰帕尔－齐夫复杂度空间分布特征，结果表明，平均而言，我国平均气温和降水量变化的复杂度约为10－11，小于随机序列的复杂度13，年平衡气温变化序列的复杂度最小，秋季平均气温变化序列的复杂度最大，季节和年平均气温序列的复杂度小于月平均气温变化序列的复杂度，月总降水量变化序列的复杂度为西部，北部大于南部和东部，我国东南沿海地区气候要素变化的复杂度最大。     

近四十年我国气候变化的初步分析

利用NCEP/NCAR（National Centers for Environmental Prediction/National Center for Atmospheric Research）2001-2010年再分析资料,检验了全球气候系统模式CESM中大气模块CAM（Community Atmosphere Model）对亚洲夏季风和大气热源的模拟能力。结果显示,模式可以再现亚洲夏季风和大气热源的主要特征。通过敏感试验探讨人为气溶胶影响亚洲夏季风的机理,分析、讨论了气溶胶引起的非均匀加热的变化对辐散风和无辐散风强度的影响,在机理上解释了亚洲夏季风减弱的原因。结果表明,人为气溶胶浓度的升高使东亚夏季风强度在中国东南地区、中南半岛北部和印度半岛北部减弱。而中国东南部季风的减弱促使中国内陆降水减少,沿海降水增多。进一步分析人为气溶胶浓度升高的作用发现,其改变了大气热源的分布,造成阿拉伯海、孟加拉湾和中国南海大气热源增强,中国东部地区和中南半岛大气热源减弱,其中气溶胶通过影响凝结潜热来改变大气热源,主要是对对流过程的影响。此外,大气热源分布的变化改变了季风区的热力结构,使中国东南地区、中南半岛北部的加热减弱,从而减少了全位能的产生,使得全位能向辐散风的转换减小,辐散风减弱;同时,中国东南部、中南半岛北部季风由于辐散风向无辐散风转换的减弱,无辐散风减弱,最终导致了夏季风强度的减弱。而且,人为气溶胶对亚洲夏季风的影响主要通过大气热力和动力过程的响应产生作用。     

Preliminary analysis of climatic variation during the last 39 years in China

The preliminary analysis of climatic variation in China during the last 39 years has been made in this paper. The results show that although the global climate is getting warmer, some parts of China are cooling. The warming only occurs in Northeast, North and the west part of Northwest China while the areas between about 35oN and Nanling Mountain, east of the Tibetan Plateau in China are getting cooler. The cooling centers are located in Sichuan, the south part of Shaanxi and the north part of Yunnan respectively. According to the theory of greenhouse effect, there are much precipitation at low and high latitudes and less precipitation in middle latitude. However, the precipitation in the most parts of China has been decreased, especially in North and Northwest China.     

The characteristics of climate change over the Tibetan Plateau in the last 40 years and the detection of climatic jumps

Through analyzing the yearly average data obtained from 123 regular meteorological observatorieslocated in the Tibetan Plateau (T-P), this article studies the characteristics of climate change in T-P inthe last 40 years. From the distribution of the linear trend, it can be concluded that the southeasternpart of T-P becomes warmer and wetter, with an obvious increase of rainfall. The same characteristicsare found in the southwestern part of T-P, but the shift is smaller. In the middle of T-P, temperature andhumidity obviously increase with the center of the increase in Bangoin-Amdo. The south of the TarimBasin also exhibits the same tendency. The reason for this area being humid is that it gets less sunshineand milder wind. The northeastern part of T-P turns warmer and drier. Qaidam Basin and its westernand southern areas are the center of this shift, in which the living environment is deteriorating. Analyzingthe characteristics of the regional average time series, it can be found that in the mid-1970s, a significantsudden change occurred to annual rainfall, yearly average snow-accumulation days and surface pressurein the eastern part of T-P. In the mid-1980s, another evident climatic jump happened to yearly averagetemperature, total cloud amount, surface pressure, relative humidity, and sunshine duration in the samearea. That is, in the mid 1980s, the plateau experienced a climatic jump that is featured by the increase oftemperature, snow-accumulation days, relative humidity, surface pressure, and by the decrease of sunshineduration and total cloud amount. The sudden climatic change of temperature in T-P is later than that ofthe global-mean temperature. From this paper it can be seen that in the middle of the 1980s, a climaticjump from warm-dry to warm-wet occurred in T-P.     

Where and when did an abrupt climatic change occur in China during the last 43 years?

Summary A climatic regionalization of the atmospheric drought indices (ADI) in both winter and summer over China was carried out utilizing orthogonally rotated principal component (RPC) analysis. An abrupt climatic change in the last 43 years was identified with the Mann-Kendall test, the sequential t-test, and the criterion of signal/noise for time series of the regional ADI in winter and summer. The results obtained with three statistic tests were also compared.It is found that a drought in winter persisted for almost 21 years from around 1972, and a slightly persistent drought in summer started from around 1961 in the Northern part of China. In addition, a summer climatic jump to a drought appeared around 1979 in South China. However, a weak abrupt change from drought to a wet spell in summer occurred around 1970 in Middle China during the period from 1959 to 1984.With 7 Figures     

The reduction of global radiation in south-eastern Norway during the last 50 years

Summary At the Norwegian University of Life Sciences (previously known as the Agricultural University of Norway), measurements of global radiation have been performed since 1949. Rurally located, 35 km south of Oslo (59°40′N, 10°46′E), the local climate is not affected by industry or heavy traffic. The recent focus on global dimming in the scientific literature, and the impact a reduction of solar radiation on the Earth’s surface would have on agriculture and the biosphere in general, motivated us to collect and analyze the global radiation data. On a monthly basis, the reduction in radiation varied between more than 4% per decade in April and June to less than 2% per decade in January and May. The analyses show a reduction in the annual sum of global radiation by 2.5% or 3.1% per decade, depending on whether analyses were restricted to years with reliable and complete data sets (31 years from 1950 to 2003) or included all individual months with reliable data (545 months) were used.     

Recent progress in studies on land cover change and its regional climatic effects over China during historical times

The recent progresses on the reconstruction of historical land cover and the studies on regional climatic effects to temperature,precipitation,and the East Asian Monsoon across China were reviewed.Findings show that the land cover in China has been significantly modified by human activities over the last several thousands years,mainly through cropland expansion and forest clearance.The cropland over traditional Chinese agricultural areas increased from 5.32×105 km2 in the mid-17th century to 8.27×105 km2 in...     

近几年我国霾污染实时季节预测概要

近些年,中国东部经历了严重的霾污染,对人体健康、交通安全、生态系统以及社会经济有巨大的危害。在1周以内的霾污染预报之外,季节尺度的霾污染预测可以给减排治污措施的制定提供更长时间尺度的科学支撑。本文以年际增量为预测对象,选取前期外强迫因子为自变量,分别针对京津冀和长三角区域建立逐月的冬季霾日数季节尺度预测模型,并开展了实时的季节预测。总体来看,京津冀和长三角区域预测模型的性能大体处于相似的水平,均方根误差在2 d左右,对距平符号的捕捉率在80%以上,对霾日数变化的长期趋势具有很好的再现能力。在2016/2017年冬季京津冀霾日数实时预测中,模型预测的结果相对于常年值的定性结论全部准确,相对于前一年污染状况的结论大多数准确。在2017/2018年冬季长三角霾日数实时预测中,12月和1月的预测误差较小,2月的预测误差在2 d左右。     

Urban heat island effect on annual mean temperature during the last 50 years in China

Summary Based on Chinas fifth population survey (2000) data and homogenized annual mean surface air temperature data, the urban heat island (UHI) effect on the warming during the last 50 years in China was analyzed in this study. In most cities with population over 10⁴, where there are national reference stations and principal stations, most of the temperature series are inevitably affected by the UHI effect. To detect the UHI effect, the annual mean surface air temperature (SAT) time series were firstly classified into 5 subregions by using Rotated Principal Components Analysis (RPCA) according to its high and low frequency climatic change features. Then the average UHI effect on each subregions regional annual mean STA was studied. Results indicate that the UHI effect on the annual mean temperatures includes three aspects: increase of the average values, decrease of variances and change of the climatic trends. The effect on the climatic trends is different from region to region. In the Yangtze River Valley and South China, the UHI effect enhances the warming trends by about 0.011°C/decade. In the other areas, such as Northeast, North-China, and Northwest, UHI has little impact on the warming trends of the regional annual temperature; while in the Southwest of China, introducing UHI stations slows down the warming trend by –0.006°C/decade. But no matter what subregion it is, the total warming/cooling of these effects is much smaller than the background change in regional temperature. The average UHI effect for the entire country, during the last 50 years is less than 0.06°C, which agrees well with the IPCC (2001). This suggests that we cannot conclude that urbanization during the last 50 years has had much obvious effect on the observed warming in China.     

春夏东亚大气环流年代际转折的影响及其可能机理

本文通过多变量联合经验正交分解(MV-EOF)方法揭示了近30年(1979~2010年) 春季和夏季东亚大气环流所发生的年代际转折及其与中国南方降水年代际季节反相变化的内在联系,探讨了局地性大气热源年代际变化影响东亚大气环流年代际转折的可能机理.结果表明:(1)东亚大气环流春季第一模态和夏季第二模态在90年代中期都发生了明显的年代际转折;(2)与春季大气环流第一模态和夏季大气环流第二模态年代际转折相对应的是中国南方降水明显的年代际季节反相变化,即春季降水年代际减少,夏季降水年代际增多;(3)春季青藏高原和夏季贝加尔湖地区大气热源年代际变化对东亚大气环流年代际转折有一定贡献,是造成中国南方降水年代际季节反相变化的直接原因;(4)春季青藏高原大气热源的年代际减弱,使得高原东南侧的西南风减弱,导致中国南方上空水汽输送不足,春季降水减少.夏季贝加尔湖大气热源偶极型分布由“南负北正”转变为“南正北负”,由此在贝湖上空激发高压异常,使得夏季雨带北进受阻而停滞南方,造成中国南方夏季降水增多.     

我国西北地区近50年降水和温度的变化

用近50年的每月温度和降水资料研究了我国西北地区的气候变化.结果表明:(1)该地区在1986年附近发生了一次明显的气候跃变,要比全国气候跃变晚6～8年;(2)跃变后比跃变前全区年平均气温上升了0.51℃,冬季上升了1.27℃;(3)跃变后比跃变前全区年降水总量上升了5.2%,夏季上升了6.8%.进而讨论了温度和降水的增加对该地区生态环境的影响.     

我国干旱半干旱区气候变化特征及其对干湿波动的影响

气候干湿状况是表征区域气候特征的重要指标,是在全球气候变暖背景下,水循环与陆面蒸散发作用的综合结果。本文从湿润度指数入手,结合降水与潜在蒸散的时空变化,分析了我国干旱半干旱区气候特点与干湿变化特征及对土壤湿度的影响。分析发现：近50年来,我国干旱与半干旱区均呈变湿趋势。干旱区与半干旱区潜在蒸散与降水月差值在年内出现时间上存在不一致,且干旱区明显大于半干旱区;3～9月为干旱气候区潜在蒸散与降水差值大值期,3～6月半干旱区潜在蒸散明显大于降水,7月起差值明显减小。作用分析表明,在干旱区,降水对湿润度指数的影响更大,而对于半干旱区,降水与潜在蒸散作用相当。长期以来,我国整个干旱与半干旱区大部分土壤湿度在逐渐变干,尤其是农业耕作层的浅层土壤,几乎全区域一致呈现变干趋势,说明我国干旱半干旱区农牧业生产存在较大的潜在干旱风险。     

Impacts of two types of northward jumps of the East Asian upper-tropospheric jet stream in midsummer on rainfall in eastern China

The East Asian upper-tropospheric jet stream (EAJS) typically jumps north of 45°N in midsummer. These annual northward jumps are mostly classified into two dominant types: the first type corresponds to the enhanced westerly to the north of the EAJS’s axis (type A), while the second type is related to the weakened westerly within the EAJS’s axis (type B). In this study, the impacts of these two types of northward jumps on rainfall in eastern China are investigated. Our results show that rainfall significantly increases in northern Northeast China and decreases in the Yellow River-Huaihe River valleys, as well as in North China, during the type A jump. As a result of the type B jump, rainfall is enhanced in North China and suppressed in the Yangtze River valley. The changes in rainfall in eastern China during these two types of northward jumps are mainly caused by the northward shifts of the ascending air flow that is directly related to the EAJS. Concurrent with the type A (B) jump, the EAJS-related ascending branch moves from the Yangtze-Huai River valley to northern Northeast (North) China when the EAJS’s axis jumps from 40°N to 55°N (50°N). Meanwhile, the type A jump also strengthens the Northeast Asian low in the lower troposphere, leading to more moisture transport to northern Northeast China. The type B jump, however, induces a northwestward extension of the lower-tropospheric western North Pacific subtropical high and more moisture transport to North China.     

近54a湖南区域暴雨的时空分布特征

基于1960—2013年湖南88个台站逐日降水数据,采取线性趋势分析等方法分析了近54 a湖南区域暴雨的时空分布特征。从时间变化上看,近54 a湖南区域暴雨日以6月208 d为最多,1月0 d为最少;夏季、春季、秋季及冬季区域暴雨日数占总日数的百分比依次为60%、29%、10%及1%。暴雨日数、暴雨强度均值突变点分别为1994年、1995年,暴雨初日的均值突变点为1983、1994年,暴雨终日无均值突变;暴雨日数与暴雨强度(暴雨发生终日)总体上呈上升(后延)趋势。基于突变点分段线性趋势分析表明,仅暴雨日数在1994—2013年及暴雨强度在1960—1994年期间呈显著下降趋势。从空间分布上看,区域暴雨强度及其与非区域暴雨强度的差值、区域暴雨持续2日或以上的暴雨强度及其与单日暴雨强度的差值的大值区主要位于湘西北及湘东南,小值区主要位于湘西南-湘东北的带状区域;全部站点的区域暴雨强度均大于非区域暴雨强度,89%的台站持续2日或以上的区域暴雨强度大于单日区域暴雨强度。区域暴雨、总体暴雨的台站暴雨最长持续日数分别为1~4 d、2~4 d,均集中在2~3 d且其站数占总站数的百分比分别为97.7%、96.6%。     

近50年来中国极端降水趋势与物理成因研究综述

2021年8月11日20时—12日20时（北京时,下同）湖北北部发生极端降水,24 h降水量最大达518.5 mm,1 h降水量最大达117.9 mm,造成了严重灾害。基于常规气象观测资料和ERA5再分析资料,采用统计学方法和天气学诊断分析法,对该过程极端降水的特征及天气学成因进行初步分析。利用常规气象观测资料和ERA5再分析资料,对2021年8月12日湖北省北部极端降水特征及其中尺度演变特征、环流形势和物理量极端性的天气学成因进行初步分析。结果表明：（1）不同区域降水性质不同,总体有累计降水量大、小时雨强强、降水时段集中、极端性突出、致灾性强等特点。（2）β中尺度对流云团发展迅速、持续时间长、东移速度慢是造成此次极端降水的主要因素。（3）高层南亚高压、高空急流以及中层副热带高压和低槽是主要影响系统,中低层切变线、低层低涡以及偏东急流是直接参与者。（4）925—850 hPa低涡和偏东急流异常强盛且长时间维持,导致低层形成强动力辐合中心和强水汽辐合中心,有利于700 hPa以下上升运动发展和维持。偏东急流也有利于低层能量锋加强南压以及θ_se高能区和对流不稳定层结的建立,促进对流性强降水的发生发展。（5）925—850 hPa的涡度、垂直速度、比湿和整层可降水量均表现出异常的极端性,且其异常度演变趋势与雨强演变趋势基本一致。

     

近50年中国气温日较差的变化趋势分析

利用近50年的气温观测资料,对中国地区的气温日较差的空间分布和时间序列变化特征进行了分析。同时分析了与日最高气温、最低气温以及平均气温时空分布之间的关系。结果发现,近50年来气温日较差呈下降趋势,其平均减小幅度为高纬度地区大于低纬度地区;不同地区及同一地区的DTR季节变化特征也不相同,我国北方多为冬季DTR下降最大,其次是春季和秋季,夏季最小。在黄淮和长江流域,以夏季和春季DTR下降最为显著。华南地区仍以冬季下降最大。气温日较差整体呈现下降趋势,中高纬度下降比低纬度明显。在相同纬度带上,由于地理状况的不同,变化趋势有所不同。同时,气温日较差的变化有明显的区域和季节性差异,特别在西部的青藏高原和新疆地区的DTR变化与东部地区的差异明显。     

近50a华北暴雨研究主要进展

在我国加快实现气象业务现代化进程及2012年7月21日北京出现特大暴雨洪涝灾害的背景下,较为系统地回顾总结了近50 a华北暴雨的主要研究进展,其内容涉及大尺度环流形势及其分型、中低纬度系统相互作用、水汽输送、高低空急流、直接造成暴雨的中尺度系统、复杂地形以及下垫面、气候学特征等诸多方面。对这些研究成果的梳理,旨在加深对华北暴雨的理解和认识,加强华北暴雨研究,提高华北暴雨的预报水平。提出在继续开展大尺度系统发展演变研究的同时,有必要借助新型观测和数值模拟手段,有针对性地开展华北暴雨β（γ）中尺度系统细致研究,以期更清楚地揭示华北暴雨中尺度系统的三维结构特征、发生发展机理。     

贵州省50年来气候变化特征

利用1951～2000年贵州省15个气象站的月平均气温、降水量资料,对贵州省50年来的气候变化作了全面的分析.     

中国东部夏季气候20世纪80年代后期的年代际转型及其可能成因

指出了中国东部夏季气候在20世纪80年代末出现了一次明显的年代际气候转型。伴随着这次年代际转型,80年代末以后中国东部南方地区降水明显增多,500 hPa西太平洋副热带高压西伸且南北范围变大,西北太平洋上空850 hPa反气旋增强。中国东部夏季80年代后期出现南方多雨的年代际转型与欧亚大陆春季积雪、西北太平洋夏季海面温度的年代际变化存在密切联系,它们也都在80年代末出现年代际转型。从80年代末以后,伴随着欧亚大陆春季积雪明显减少和西北太平洋夏季海面温度明显增高,中国夏季南方降水明显增加。文中分析了欧亚大陆春季积雪和西北太平洋夏季海面温度影响中国降水的物理过程,指出欧亚大陆春季积雪能够在500 hPa激发出大气中的遥相关波列,所激发出的波列可以从春季一直持续到夏季,造成中国北方为高压控制,南方为微弱低压控制,使得降水出现在中国南方。西北太平洋夏季海面温度的升高能够减小海陆热力差异,使得夏季风减弱,导致中国南方地区降水增多。     

北极地区极昼气候突变现象及转型成因研究

基于1979-2018年的NCEP-DOE Reanalysis Ⅱ逐日再分析数据,采用模糊C均值聚类算法(Fuzzy C-Means Algorithm,FCMA)将北极地区极昼期间的气候分为寒干型、半寒干型、半暖湿型及暖湿型4种.在夏季北极海冰快速减少的气候背景下,这4种气候型控制的区域也相应发生了明显变化.其中,...