我国东部4-9月大尺度南北旱涝的特征及变化

研究了我国东部4—9月逐月、逐季降水的跷跷板结构和气候特征,结果表明:不同时段跷跷板结构的位置和强度不同。当时间尺度加大时,南北旱涝特征更明显。定义并计算了1951—2003年我国的南北旱涝指数。对夏季和8月典型南北旱涝年进行差异的显著性t检验,表明南北旱涝年的划分是合理的。研究了1951—2003年我国南北旱涝特征的长期趋势和年代际变化;研究了南北旱涝指数与冷暖事件年的关系。结果表明,冷暖事件年对6月、6—7月以及夏季大尺度南北旱涝有影响,暖事件年有利于发生北旱南涝;而冷事件年则相反。结果还表明,冷暖事件仅是我国南北旱涝分布的一个影响因素。     

ANALYSIS OF THE CHARACTERISTICS OF RAINFALL AND LINEAR TREND IN MENGLUN, XISHUANGBANNA, SOUTHWEST CHINA

1 INTRODUCTIONAs one of the main factors affecting input and useof precipitation by forests, rainfall also makes adifference on partitioning of gross precipitation overthe canopy, equilibrium of water amount in river basinsand water cycling processes[1-4]…     

中国气候与环境演变评估(I):中国气候与环境变化及未来趋势

近百年来,全球气候正经历着一次以变暖为主要特征的显著变化,全球气候与环境的重大变化对中国的气候与环境演变也产生了重大影响。来自气候、环境、海洋和经济社会科学等领域的百余位专家和学者对中国气候与环境的演变及其对自然生态系统和社会经济部门的影响进行了评估,在此基础上,提出了适应和减缓气候变化的对策。本文主要阐述在全球气候变化背景下中国气候与环境的演变,并对未来气候变化的趋势做出了预测。     

Long-Term Trend and Abrupt Change for Major Climate Variables in the Upper Yellow River Basin

On the basis of the mean air temperature, precipitation, sunshine duration, and pan evaporation from 23 meteorological stations in the upper Yellow River Basin from 1960 to 2001, the feasibility of using hypothesis test techniques to detect the long-term trend for major climate variables has been investigated. Parametric tests are limited by the assumptions such as the normality and constant variance of the error terms. Nonparametric tests have not these additional assumptions and are better adapted to the trend test for hydro-meteorological time series. The possible trends of annual and monthly climatic time series are detected by using a non-parametric method and the abrupt changes have been examined in terms of 5-yr moving averaged seasonal and annual series by using moving T-test (MTT) method, Yamamoto method, and Mann-Kendall method. The results show that the annual mean temperature has increased by 0.8℃in the upper Yellow River Basin during the past 42 years. The warmest center was located in the northern part of the basin. The nonlinear tendency for annual precipitation was negative during the same period. The declining center for annual precipitation was located in the eastern part and the center of the basin. The variation of annual precipitation in the upper Yellow River Basin during the past 42 years exhibited an increasing tendency from 1972 to 1989 and a decreasing tendency from 1990 to 2001. The nonlinear tendencies for annual sunshine duration and pan evaporation were also negative. They have decreased by 125.6 h and 161.3 mm during the past 42 years, respectively. The test for abrupt changes by using MTT method shows that an abrupt wanning occurred in the late 1980s. An abrupt change of the annual mean precipitation occurred in the middle 1980s and an abrupt change of the mean sunshine duration took place in the early 1980s. For the annual mean pan evaporation, two abrupt changes took place in the 1980s and the early 1990s. The test results of the Yamamoto method show that the abrupt changes mostly occurred in the 1980s, and two acute abrupt changes were tested for the spring pan evaporation in 1981 and for the annual mean temperature in 1985. According to the Mann-Kendall method, the abrupt changes of the temperature mainly occurred in the 1990s, the pan evaporation abrupt changes mostly occurred in the 1960s, and the abrupt changes of the sunshine duration primarily took place in the 1980s. Although the results obtained by using three methods are different, it is undoubted that jumps have indeed occurred in the last four decades.     

广州地区酸雨长期变化趋势分析

根据1992—2012年的酸雨观测记录,对广州地区的酸雨变化特征及其长期趋势进行了统计分析。结果表明,近21年,广州地区酸雨年、季、月变化明显,降水年均pH最低出现在1998年,其年均pH为3.43,最高出现在2012年,其年均pH为4.65。降水pH大体经历了两个阶段,1998年以前降水pH呈现波动式下降,平均变化率约为-0.14a-1,1999年后降水pH逐年增大,特别是2009年后降水pH稳步增长,平均变化率约为0.03a-1;春季酸雨污染严重,夏、秋季次之,而冬季酸雨污染相对较轻;各月降水pH均较低,pH最高月出现在12月,平均值为4.36,2月pH最低,为3.95。在污染源稳定的情况下,降水强度影响pH,降水量增大时,降水pH越高,降水电导率K也越低;风速越大,降水pH则越高,降水电导率K则越小,酸雨发生频率也越小;风向影响降水pH,出现偏西风时,酸雨污染相对严重。     

阿尔山地区积雪变化特征

选取阿尔山气象站1981—2015年冷季(10月—次年4月)气象资料,利用滑动平均、线性倾向估计和Mann-Kendall等方法,对年最大积雪深度、积雪日数、气温和降水量进行分析。结果表明,阿尔山地区年最大积雪深度主要发生在1月至3月,其中2月份概率最大,达50%;34 a内最大积雪深度呈上升趋势(2.77 cm/10a),年平均增加0.98%,且年最大积雪深度在1998年发生了突变,即在1998年之前增长缓慢,在2000年以后上升趋势显著。积雪日数的统计分析表明,初始积雪日数和有效积雪日数呈现略微减少趋势,而稳定积雪日数有微弱的增加趋势;通常初始积雪日数比有效积雪日数大30天左右。年最大积雪深度与稳定积雪时期的降水量、积雪日数、日照时数有显著的相关性,相关系数分别为0.647、0.515、0.584,但与稳定积雪时期的气温没有明显的相关性。在全球变暖的大环境下,积雪深度随着降水量和日照时数的增加而增加,且积雪深度受降水量的影响大于日照时数的影响。     

长江上游流域秋季连阴雨时空变化特征

利用长江上游259个气象站逐日降水资料,采用线性趋势分析方法,分析了近1961—2012年来长江上游流域秋季连阴雨的时空变化特征。结果表明,长江上游流域秋季连阴雨过程平均出现1.54次/a,其中9月出现次数最多,10月次之,11月出现较少。秋季连阴雨日数、累积降水量分别以2.3 d/(10 a)、13.7 mm/(10 a)的速率显著减少,连阴雨开始和结束日期平均为9月9日和9月30日均表现出推迟趋势。进入21世纪后,5—9 d、10 d以上连阴雨过程的次数、80.0 mm以上连阴雨过程的次数均表现出减少趋势。金沙江下游和四川盆地东部为秋季连阴雨累计雨量及其变化速率的大值中心,四川盆地西南部为连阴雨日数及其变化速率的大值中心。9月的降水中心、雨日分布情况与秋季总体情况基本一致,10月降水中心、阴雨日数的中心出现了明显东撤,11月东撤更为明显。     

2050年前中国雾日变化趋势的预估

 利用1971-2005年中国591个气象台站的雾日资料以及逐日最低气温、相对湿度、平均风速资料,分析了35 a来中国各区域年雾日数与这些因子的相关关系,并利用IPCC第四次评估报告所提供的模式数据资料,针对3种不同的排放情景,对21世纪上半叶各区域年平均雾日进行预估。结果表明：对划分的9个雾区的年雾日数的回归方程的拟合效果较好,可以用来进行预估;未来50 a中国大部分地区雾日呈明显减少的变化趋势,在A1B,A2和B1情景下,雾日减少的平均幅度分别为16.2%,13.4%和12.9%。未来50 a中国雾日预估结果的空间分布显示：3种情景下未来中国大部分雾区雾日数都将减少,个别地区雾日数有增加趋势,其中A1B情景下雾日减少区的减少趋势最明显,而B1情景下雾日增加区的增加趋势最明显。     

Highly Oxidized Magma and Fluid Evolution of Miocene Qulong Giant Porphyry Cu‐Mo Deposit,Southern Tibet,China

The Miocene Qulong porphyry Cu‐Mo deposit, which is located at the Gangdese orogenic belt of Southern Tibet, is the largest porphyry‐type deposit in China, with confirmed Cu ～10 Mt and Mo ～0.5 Mt. It is spatially and temporally associated with multiphase granitic intrusions, which is accompanied by large‐scale hydrothermal alteration and mineralization zones, including abundant hydrothermal anhydrite. In addition to hydrothermal anhydrite, magmatic anhydrite is present as inclusions in plagioclase, interstitial minerals between plagioclase and quartz, and phenocrysts in unaltered granodiorite porphyry, usually in association with clusters of sulfur‐rich apatite in the Qulong deposit. These observations indicate that the Qulong magma‐hydrothermal system was highly oxidized and sulfur‐rich. Three main types of fluid inclusions are observed in the quartz phenocrysts and veins in the porphyry: (i) liquid‐rich; (ii) polyphase high‐salinity; and (iii) vapor‐rich inclusions. Homogenization temperatures and salinities of all type inclusions decrease from the quartz phenocrysts in the porphyry to hydrothermal veins (A, B, D veins). Microthermometric study suggests copper‐bearing sulfides precipitated at about 320–400°C in A and B veins. Fluid boiling is assumed for the early stage of mineralization, and these fluids may have been trapped at about 35–60 Mpa at 460–510°C and 28–42 Mpa at 400–450°C, corresponding to trapping depths of 1.4–2.4 km and 1.1–1.7 km, respectively.     

1951—2009年中国不同区域气温和降水量变化特征

为了研究中国不同区域气候变化特征,将全国按照气候区域划分为11个气候区,并利用1951—2009年中国194个国家基本/基准站月、年气温和降水观测资料,对全国及每个气候区平均温度及降水量的年和季节变化特征进行分析。结果表明：中国及各地区增温趋势均为极显著增加,尤其近20 a增温速度更快;而2007年成为有记录以来最暖的一年;中国冬季平均温度上升趋势最明显,春季次之,夏季几乎没有变化。中国平均年总降水量20世纪50年代最多,2000年代最少;而华北地区的年降水量减少最快;在四季降水中,中国只有夏季降水量波动略有增加,且各区域降水分布具有明显的南北差异特征。