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1.
依据青藏高原目前所取得冰芯的尘埃分析结果,初步分析了近1000年来青藏高原南北大气尘埃载荷的时空变化特征。研究表明,高原南部达索普冰芯记录的高尘埃含量时期为1270s~1380s和1870s~1990s,而北部马兰冰芯记录的高尘埃含量时期为1130s~1550s和1770s~1940s。近1000年来青藏高原南北冰芯中尘埃含量呈现不同程度的增加总趋势,这可能指示了环境的变干趋势。青藏高原冰芯记录还反映出,高原北部地区大气中的尘埃载荷明显高于南部地区;高原北部地区大气尘埃载荷春季最大,而南部地区非季风季节最大。另外,通过对高原南北冰芯中尘埃含量记录与δ18 O记录之间相关关系分析,揭示出大气尘埃载荷变化与气温变化之间关系在高原北部地区呈显著负相关,而在南部地区却呈显著正相关。这说明青藏高原南北气候环境变化的差异性。 相似文献
2.
C. Giraudi 《第四纪科学杂志》2004,19(6):537-545
The island of Lampedusa lies on the northern edge of the African continental shelf, but during some Quaternary marine lowstands it was joined to the African continent. The study and dating of the aeolian, alluvial, detrital sediments, calcareous crusts and speleothems have established that the climatic–environmental variations recorded on the island can be related chronologically to those known for northern Libya, Tunisia and the Italian peninsula. During the Last Glacial Maximum, phases of Saharan dust accumulation on Lampedusa occurred, and were coeval with dust accumulation in crater lakes and on high mountains in central‐southern Italy, and with phases of glacial advance in the Apennines and in the Alps. During the late Holocene, accumulation of Saharan dust on Lampedusa occurred but there was little accumulation of dust on the northern side of the Mediterranean Sea. With the new data from Lampedusa, it is possible to envisage two different scenarios of atmospheric circulation relating to the Last Glacial Maximum and to the late Holocene. During the Last Glacial Maximum, southerly atmospheric circulation brought rainfall to the southern slopes of the Alps and to the Apennines. During the late Holocene, a prevalent westerly atmospheric circulation became established in the northern Mediterranean. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
3.
中国大陆现代降水表现出若干长期变化特征,对现代降水趋势性变化的原因,目前还没有很好了解。结合多种资料分析以及前人研究成果,对中国大陆近几十年降水变化趋势的原因进行了探讨,得到以下初步认识:① 现代降水量变化趋势具有明显的地域性差异,全国平均没有表现出显著增加或减少的长期变化,但强降水事件频率和降水量出现明显增多,而小雨事件特别是痕量降水事件显著减少。② 再分析资料表明,最近几十年全国水汽净收支量在一定程度上增加了,实际观测资料显示近地面和对流层中下层空气比湿或大气可降水量出现较明显上升趋势。③ 代用资料序列分析显示,全国大部地区近几十年降水变化仍处于晚近历史时期正常自然波动范围内;近百年观测的降水量序列也表明,黄淮海地区降水具有多重时间尺度相互叠加作用特点,低频自然气候变异的影响信号有清晰表现。④ 人类活动引起的大气中温室气体浓度增加对全国或东部季风区现代降水变化影响的信号,目前仍难以识别;区域性近地面风速减弱导致的雨量观测系统偏差以及大范围气溶胶浓度增加,可能是东部季风区大多数台站观测到的强降水事件频率增加和小雨频率显著减少的两个重要原因。⑤ 主要与城市化影响相关的地面观测资料系统偏差,可以部分解释现有分析表明的短历时强降水事件频率和累计降水量增加现象,同时也很可能是城市台站小雨和痕量降水事件频率明显下降的另一重要原因。 相似文献
4.
北京及其北部地区大气自然降尘矿物组成特征 总被引：1，自引：0，他引：1
为研究北京地区大气自然降尘的矿物组成特征及其时空变化规律,采用XRD分析了不同季节收集的大气降尘样品。结果表明,大气降尘主要矿物为石英,平均含量为83.19%,长石以斜长石为主;降尘中的碳酸盐类矿物主要是方解石和白云石,它们在降尘中的含量接近其在北方黄土中的含量;降尘中粘土矿物的含量较少,为1.64%~5.88%,其中有较多的高岭石,反映了研究区半湿润、较温暖的环境。聚类分析表明本区降尘按矿物组成特征可分为城市和郊区两组。与大风天气少的月份相比,大风天气频繁的月份降尘中的长石等矿物含量相对较高,而粘土矿物含量相对较低。 相似文献
5.
2000～2002年,中国北方地区频频发生沙尘暴天气,给当地和广大下游地区工农业生产、交通运输、空气质量和人民的日常生活都带来了极大危害。沙尘暴天气呈现频次高、发生时间提前、发生期时间长、强度大、影响范围广等新特征。对气候变化和地理环境背景的分析研究表明,近年来中国北方沙尘暴频繁爆发的原因主要是:1)近两年处于反厄尔尼诺(拉尼娜)事件的高峰期,使东亚冬季风频繁,导致大风天气频繁发生;2)在沙尘暴发生季节,中国北方降水明显减少,气温回升迅速且温度偏高于往年,使解冻的地表土层疏松,为沙尘暴的发生提供了丰富的沙源;3)近年来中国北方干旱加剧、土地荒漠化严重,使原本广阔的戈壁沙漠面积更加扩大,有利于沙尘暴天气的发生,这与不合理的土地利用状况有关。 相似文献
6.
Despite widespread evidence for atmospheric dust deposition prior to the Quaternary, quantitative rate data remains sparse. As dust influences both climate and biological productivity, the absence of quantitative dust data limits the comprehensiveness of models of pre-Quaternary climate and biogeochemical cycles. Here, we propose that inorganic matter contained in coal primarily records atmospheric dust deposition. To test this, we use the average concentration of inorganic matter in Permian coal to map global patterns and deposition rates of atmospheric dust over Pangea. The dust accumulation rate is calculated assuming Permian peat carbon accumulation rates in temperate climates were similar to Holocene rates and accounting for the loss of carbon during coalification. Coal-derived rates vary from 0.02 to 25 g m− 2 year− 1, values that fall within the present-day global range. A well-constrained East–West pattern of dust deposition corresponding to expected palaeoclimate gradients extends across Gondwana with maximum dust deposition rates occurring close to arid regions. A similar pattern is partially defined over the northern hemisphere. Patterns are consistent with the presence of two large global dust plumes centred on the tropics. The spatial patterns of dust deposition were also compared to dust cycle simulations for the Permian made with the Community Climate System Model version 3 (CCSM3). Key differences between the simulations and the coal data are the lack of evidence for an Antarctic dust source, higher than expected dust deposition over N and S China and greater dust deposition rates over Western Gondwana. This new coal-based dust accumulation rate data expands the pre-Neogene quantitative record of atmospheric dust and can help to inform and validate models of global circulation and biogeochemical cycles over the past 350 Myr. 相似文献
7.
玉龙雪山地区大气降水中粉尘颗粒物特征研究 总被引：4，自引：1，他引：3
以在玉龙雪山地区采集的大气降水样品为主要研究载体,分析了大气降水中粉尘颗粒物随时间的变化特征和影响大气降水中粉尘含量的潜在因素. 结果表明：大气降水中颗粒物浓度和典型粉尘特征化学离子含量的变化具有很好的一致性,且季风期末大气降水中的微粒含量显著升高,显示了明显的季节性变化特征. 丽江市和甘海子盆地大气降水中粉尘化学离子含量(SO42-,Mg2+,Ca2+,K+,NH4+,NO3-,粉尘浓度)之间具有较好的相关性,反映了这些离子共同的来源. 降水中pH值和电导率的变化很大程度上受到粉尘活动的影响,海盐气溶胶粒子对玉龙雪山地区大气降水中典型粉尘微粒(除Cl-和部分Na+之外)的沉降没有贡献. 此外,降水化学和微粒分析表明,丽江市区的大气环境不排除人为活动的影响. 相似文献
8.
SEDIMENTARY CHARACTERISTICS AND CLIMATIC ANALYSIS OF EASTERLY DUST STORMS IN THE NEGEV (ISRAEL) 总被引：1，自引：0，他引：1
Sedimentary and meteorological characteristics of easterly dust storms causing severe damage in the Negev in November 1958 are analysed. Though the heavy storm originated in weather conditions outside of the affected area, the intense dustiness was of a more local nature. The sedimentological character of the dust indicates that the largest portion was of local origin, picked up by the turbulent current in the loess area of the northern Negev on its passage westward. Total quantity of sediment transported in the Beersheba Basin is estimated to be 10–20 million tons. The analysis of climatic data and of sedimentary characteristics of several other dust samples indicates that though severe dust storms can produce dramatic effects in transporting and deposition of aeolian dust, the rare occurrence of easterly dust storms does not make it likely that they were responsible for the import of aeolian sediments found in the northern Negev. 相似文献
9.
文章依据冰芯、树木年轮等自然记录和历史文献记录,分析了中国北方不同地区近2000年的沙尘事件及其与气候变化的关系。结果表明,在干旱区西部,历史时期的沙尘变化主要受温度变化的制约,无论在10年尺度,还是百年尺度上,沙尘事件与温度变化均表现为显著的反相关,即气候寒冷期与沙尘频发事件相对应,气候温暖期与沙尘发生变弱期一致;在半干旱区,在10年尺度上温度和降水序列与沙尘发生频率均显著负相关,但在百年尺度上沙尘与降水变化的关系更为密切;在干旱区东部,沙尘与气候变化的关系具有明显的过渡性特征,气候变化对沙尘事件的作用主要在百年尺度上体现出来,沙尘与温度记录的负相关比降水更好,在10年尺度上气候与沙尘序列尽管也是负相关,但不显著。通过对现代气象记录的气温、降水变化和沙尘事件频数分析,其结果与历史时期情况基本一致。 相似文献
10.
苏干湖沉积物粒度组成记录尘暴事件的初步研究* 总被引：6，自引：13，他引：6
文章通过分析苏干湖表层沉积物、流域表层沉积物、大气降尘以及湖泊冰面囚固碎屑颗粒等的粒度组成,比较了流域地表沉积与湖泊沉积物粒度组成的差异和苏干湖表层沉积粒度组成的空间变化。初步认为苏干湖沉积物粗颗粒组分(>63μm)主要由风力搬运入湖,>63μm组分的含量可以用来指示研究区尘暴事件的演化。结合湖泊沉积岩芯纹层计数年龄,重建的1000年来尘暴演化历史显示,在1210A.D.之前尘暴事件较弱,且变化幅度较小;1210A.D.以来则表现出高频率或者高强度,其中13世纪上半叶以及17世纪的高值段与东部降尘变化历史一致。就气候变化的特征时段(中世纪暖期、小冰期等)而言,尘暴事件主要与气候变冷情况下较强的盛行风场有关;而极端干旱区有效湿度的增加可能有利于地表粉尘的释放,助长了尘暴事件的发生。 相似文献
11.
North Atlantic control on precipitation pattern in the eastern Mediterranean/Black Sea region during the last glacial 总被引：1，自引：0，他引：1
Olga Kwiecien Helge W. Arz Frank Lamy Birgit Plessen Andr Bahr Gerald H. Haug 《Quaternary Research》2009,71(3):375-384
Based on proxy records from western Black Sea cores, we provide a comprehensive study of climate change during the last glacial maximum and late-glacial period in the Black Sea region. For the first time we present a record of relative changes in precipitation for NW Anatolia based on variations in the terrigenous supply expressed as detrital carbonate concentration. The good correspondence between reconstructed rainfall intensity in NW Anatolia and past western Mediterranean sea surface temperatures (SSTs) implies that during the glacial period the precipitation variability was controlled, like today, by Mediterranean cyclonic disturbances. Periods of reduced precipitation correlate well with low SSTs in the Mediterranean related to Heinrich events H1 and H2. Stable oxygen isotopes and lithological and mineralogical data point to a significant modification in the dominant freshwater/sediment source concomitant to the meltwater inflow after 16.4 cal ka BP. This change implies intensification of the northern sediment source and, with other records from the Mediterranean region, consistently suggests a reorganization of the atmospheric circulation pattern affecting the hydrology of the European continent. The early deglacial northward retreat of both atmospheric and oceanic polar fronts was responsible for the warming in the Mediterranean region, leading simultaneously to more humid conditions in central and northern Europe. 相似文献
12.
Using the Total Ozone Mapping Spectrometer (TOMS) data from the National Aeronautics and Space Administration (NASA) earth satellites, the Aerosol Optical Depth (AOD) as indicated by AOD Index (AI) for the period 1978–2005 is analyzed for northern China. The spatial distribution of annual mean AI has the largest values in the desert regions of northwestern China, such as southern Xinjiang Taklimakan Basin, western Gansu and Qinghai’s Qaidam Basin. Large values are found in western Inner Mongolia, the Jogger Basin, and north of the Loess Plateau, as well as in the North China and Northeast China Plains. In Northern China, the AI of spring and summer is larger than in other seasons. The large AI values in spring register the most extensive coverage, but the AI values in regions affected by the Asian monsoon experience a significant decrease during the summer season. The lowest AI values generally occur in autumn in North and Northeast China, but they appear in winter in the northwestern arid region. Overall, the analysis results using TOMS AI data well reflect the spatiotemporal characteristics of dust aerosol as reported previously based on the dust weather observation data, with greater consistency seen in northwestern arid and semi-arid regions. It is also realized that the TOMS AI data are potentially useful for estimating atmospheric mineral aerosol deposition flux in northern China in order to better understand the formation and evolution of China loess in the Quaternary. 相似文献
13.
Sammaneh Negah Amir-Hussain Mesakatee Sohrab Hajjam Ali Kamali 《Arabian Journal of Geosciences》2016,9(15):649
For the very first time, the mesoscale circulation patterns and synoptic-dynamic structure of the atmospheric systems that led to the dust emission to the south coast region of Caspian Sea (SCRCS) were identified and classified using the region synoptic stations’ observations of 2005–2013. Satellite measurements and images, NCEP/NCAR reanalysis data, and Weather Research and Forecasting (WRF) model coupled with Chemistry (WRF-CHEM) model products were also used in this study. Results showed that in 49 % of cases, cyclonic circulations over the Middle East deserts were the main transporter of dust particles into the atmosphere where then transferred to the SCRCS by southerly winds over the Alborz mountains in the lower troposphere and by westerly waves in the middle and upper troposphere. During the warm seasons, the surface heating lead to the development of mesoscale thermal low pressures over the hot deserts on the eastern regions of the Caspian Sea, like Turkmenistan and Qura Qum. Those heat lows were responsible for the 38 % of the occurred events. Turbulence and instabilities in the lower troposphere were identified as the second important dust emitter to the atmosphere where those dust particles transported to the SCRCS with the strong northeasterly wind. The third pattern by 13 % of cases was belonging to the mesoscale thermal low pressure that was developed over the arid regions of Iran like Dasht-é-Kavir. Because of the nature of the turbulence in the lower troposphere and heat lows, the ascent of dust particles by these two mechanisms was limited to a shallow layer in the troposphere. The results of simulation with the WRF-CHEM model, analysis of moderate resolution imaging spectroradiometer (MODIS) images, and spatial zoning of atmospheric optical depth (AOD) confirmed the results of the synoptic study. 相似文献
14.
基于CMIP6气候模式的新疆积雪深度时空格局研究 总被引：1，自引：0，他引：1
积雪深度的变化对地表水热平衡起着至关重要的作用。选用了国际耦合模式比较计划第六阶段（CMIP6）中目前情景比较齐全的五个全球气候模式,通过对比新疆地区1979—2014年积雪深度长时间序列数据集,评估了气候模式在新疆地区模拟积雪深度的模拟能力,接着预估了未来不同SSPs-RCPs情景下新疆地区在2021—2040年（近期）、2041—2060年（中期）、2081—2100年（末期）相对于基准期（1995—2014年）的积雪深度变化。气温和降水对积雪深度变化有着重要的影响,因此还分析了新疆地区到21世纪末期气温和降水的变化趋势。结果表明：订正后的气候模式模拟的积雪深度数据与观测数据的相关系数均达到0.8以上,其中1月至3月与观测数据的结果更为吻合。气候模式基本上能够反映积雪深度年内变化的基本特征,气候模式模拟的积雪深度空间分布和观测数据具有相似的特征。气温和降水在未来不同情景下均会波动上升,其中气温的增幅相对比较明显,达0.43 ℃·（10a）-1,而降水的增幅为0.63 mm·（10a）-1,新疆未来的气候总体上呈现出变暖变湿的趋势。新疆地区的平均积雪深度在未来不同时期相对基准期均呈增加的趋势。SSP1-1.9情景下,21世纪近期、中期和末期北部大部分地区的积雪深度将会有所增加;SSP1-2.6情景下,北部阿尔泰山地区的积雪深度在21世纪近期有所减小,但中期和末期将会有所增加;SSP2-4.5情景下,21世纪不同时期东部地区的积雪深度将会有所增加,北部和中部大部分地区在不同时期积雪深度将会变小;SSP3-7.0情景下,21世纪不同时期北部和西南地区的积雪深度将会普遍变小,东部地区的积雪深度将普遍增加;SSP4-3.4和SSP4-6.0情景下,21世纪不同时期西南昆仑山地区的积雪深度将会普遍变小,东部地区的积雪深度将普遍增加;SSP5-8.5情景下,北部阿尔泰山地区和东部地区的积雪深度将普遍增加。 相似文献
15.
Analysis and hydrogeochemical modeling of hydrocarbonate groundwater, including its buffering geochemical properties, have
demonstrated that this water has undergone a geochemical transformation almost throughout the whole of one industrial region.
It is known that hydrocarbonate groundwater possesses a high protective natural geochemical potential, supporting neutralization
of acid atmospheric precipitation. Natural hydrocarbonate water undergoes three stages of anthropogenic transformation caused
by acid atmospheric precipitation over more than 50 years. The first stage is transformation of neutral hydrocarbonate water
into alkaline water, accompanied by calcite precipitation and sodium carbonate dissolution from the unsaturated zone. The
second stage is transformation of alkaline water into neutral hydrocarbonate water; the hydrocarbonate content, being less
than the lower limit for background concentrations, showed reduced water buffering properties or protective potential relative
to acid precipitation. The third stage is transformation of neutral hydrocarbonate water into acidic water, with a complete
loss of protective geochemical potential.
This unfavorable ecological situation with natural geochemically hydrocarbonate groundwater shows that natural groundwater
less protected from the impact of acid atmospheric precipitation is in a worse ecological condition, which is confirmed by
observations in northern and Western Europe and other regions of the world.
Received: 30 October 1997 · Accepted: 23 March 1998 相似文献
16.
Through collected precipitation samples continuously to research the precipitation chemical characteristics and the water vapor source in Shiyang River Basin, Northwestern China, a total of 121 precipitation samples had been collected in the Shiyang River Basin from July 2013 to July 2014. The results showed that, during the period of sampling, the variation range of pH value of precipitation ranged from 6.62 to 8.53 in Shiyang River Basin and the average was 7.46. The EC values ranged from 17.28 to 787.00 μs/cm, with a mean 186.66 μs/cm. Ca2+ and Na+ dominated cations and accounted for 71.80% of total cations composition, while SO4 2? and NO3 ? dominated anions with a contribution of 82.18%. The main ionic sources are local dust aerosols and the dust from Central Asia and Northwestern China arid regions brought by the westerly, and the back trajectories also supported it. Back trajectories suggested that the air mass arrived in Shiyang River Basin mainly from the dust sources region in Central or West Asia or Northwestern China through westerly circulation in dry season, while from the Indian Ocean or the Pacific Ocean through monsoon circulation in wet season. The precipitation can be divided into three types based on the vector of water vapor transportation: the monsoon precipitation, the westerly precipitation, and the interaction precipitation (precipitation influenced both by monsoon and westerly). The type of interaction precipitation was major precipitation patterns in study area, and the westerly precipitation came next. The results are also helpful for further understanding the air pollution situation caused by dust events in study area and providing scientific basis for the effective prevention and control of atmospheric pollution. 相似文献
17.
18.
近年来，我们先后在青藏高原的古里雅冰帽、唐古拉冰川和希夏邦马地区钻。取了大量冰芯。在这些冰芯中保存着大量的环境变化信息。特别是反映沙暴、尘暴和浮尘等环境事件的尘埃冰志记录，是目前我们所能得到的记录最详细、分辨率最高和最连续的资料系列。青藏高原冰芯中尘埃指标显示，在气候变冷时，青藏高原的尘暴、沙暴和浮尘等事件出现的频率增多，强度增大；在气候变暖时，则尘暴、沙暴和浮尘等事件的频率减少，强度减小。目前，在青藏高原面上，正经历着气候变暖、环境改善的过程。 相似文献
19.
This study investigated the decadal relationship between the East Asian (EA) summer precipitation (EASP) and global sea surface temperature anomaly (SSTA) patterns. Maximum covariance analysis (MCA) was used to identify the coupling relationship between EASP and global SSTA. Four leading coupling modes were identified by MCA and they explained 27.7%,12.5%,8.9%,and 7.3% of the total variance, respectively. The spatial pattern of EASP of the first leading mode exhibited more-than-normal precipitation in most regions of EA. The second mode of EASP depicted a north-south “-+-” tripole pattern. The third one showed a “wet south and dry north” pattern, and the fourth mode exhibited a north-south “+-+” tripole pattern. The four coupling modes were suggested to be modulated by the global warming, Pacific Decadal Oscillation (PDO), Atlantic Multidecadal Oscillation (AMO), and North Pacific Gyre Oscillation (NPGO), respectively.The atmospheric processes and mechanisms underlying such modulations were also investigated. In the first coupling mode, global warming was favorable for increasing water vapor and precipitation over most parts of EA. In the second mode, PDO weakened the EA summer monsoon circulation, and it decreased precipitation in northern and southern EA regions and increased precipitation in the central EA region. The third mode was affected by AMO, which displaced the EA trough southward and weakened the convective activity over the northern EA region, thus leading to deficient precipitation in northern EA region. In the fourth mode, the EA summer monsoon was strengthened by NPGO, thus increasing precipitation in the northern and southern regions and decreasing precipitation in the central region. 相似文献
20.
ANDREI A. VELICHKO OLGA K. BORISOVA ELLA M. ZELIKSON 《Boreas: An International Journal of Quaternary Research》2008,37(1):1-19
Main climatic indexes (mean January, July and annual temperatures; duration of the frost‐free period; seasonal and annual precipitation; and annual potential evaporation) are estimated for the Last Interglacial Eemian–Mikulino–Kazantsevo–Oxygen Isotopic Substage 5e) climatic optimum in northern Eurasia. Reconstructions are based on the palaeofloristic data from 29 sites. The distribution of temperature deviations from present‐day values in northern Eurasia, as well as in the northern hemisphere as a whole, indicates certain areas where temperatures during the Last Interglacial climatic optimum were lower than at present. The greatest positive deviations occurred in the high latitudes and gradually decreased towards mid‐latitudes. At about 45°N the mean January temperature was close to that of the present day. For the mean July temperature, the zone with minor deviations is situated further to the north, at 55°N. South of 50°N, an area with small negative temperature deviations from the present‐day values is reconstructed. A similar decrease in temperature deviations from high to low latitudes was the general tendency in various warm epochs, including the Holocene and the Eocene optima. In the arid and semi‐arid regions of northern Eurasia, a considerable increase in precipitation took place, while air temperatures were close to those of the present or even slightly lower. Another peculiarity of the climate in the Last Interglacial climatic optimum relates to the meridional temperature gradient, one of the factors strongly influencing the intensity of the Westerlies in the mid‐latitudes of the northern hemisphere. Our reconstructions for northern Eurasia tend to contradict this rule. The paradox can be explained by a compensation mechanism: a substantial increase in winter temperature in Siberia indicates that the Siberian atmospheric High was weaker and smaller at the Last Interglacial climatic optimum than at present. The reduced role of the Siberian High was compensated by more frequent invasions of the Atlantic air masses from the west, even though the meridional temperature gradient was smaller than at present. 相似文献