共查询到20条相似文献，搜索用时 31 毫秒
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The Intergovernmental Panel on Climate Change (IPCC) completed its first round of assessments of the science, impacts and response to climate change in 1990. In 1992, the IPCC pulled together updates to the first round of reports (J. Houghton, G.J. Jenkins and J.J. Ephraums, eds, Climate Change: The IPCC Scientific Assessment, Cambridge University Press, Cambridge, 1990; W.J. McG. Tegart, G.W. Sheldon and D.C. Griffiths, eds, Climate Change: The IPCC Impacts Assessment, Australian Government Publishing Service, Canberra, 1990). At the same time, the literature on the potential impacts of climate change has expanded enormously. Four volumes are reviewed here. 相似文献
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C. C. &#;W. LEE J. H. SAVARINO H. CACHIER M. H. THIEMENS 《Tellus. Series B, Chemical and physical meteorology》2002,54(3):193-200
The recent discovery of an anomalous enrichment in 17 O isotope in atmospheric sulfate has opened a new way to investigate the oxidation pathways of sulfur in the atmosphere. From laboratory investigations, it has been suggested that the wet oxidation of sulfur in rain droplets was responsible for the excess 17 O. In order to confirm this theory, sulfur and oxygen isotope ratios of different primary sulfates produced during fossil fuel combustion have been investigated and are reported. None of these samples exhibits any anomalous oxygen or sulfur isotopic content, as compared to urban sulfate aerosols. These results, in agreement with the laboratory investigations, reinforce the idea of an aqueous origin for the oxygen-17 anomaly found in tropospheric sulfates. 相似文献
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使用京津冀冬半年地面气象站雾的常规观测和自动站风的观测资料进行统计分析,得出太行山地形辐合线位置与华北平原雾的空间分布有一定对应关系,即：冬半年(10-2月)华北平原年平均雾日多发区对应地形辐合线的位置；以2013年1月21-22日华北平原雾为例,辐合线附近的能见度相对较低,即辐合线附近雾的浓度较强。为加强对雾天气的成因认识,提高雾天气的预报能力,在科学规划雾天气监测网时应充分考虑地形的影响(如地形辐合线的位置)。 相似文献
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利用2017-2019年空气质量监测数据，采用HYSPLIT后向轨迹模式、聚类分析、潜在源贡献因子分析法（PSCF）和浓度权重轨迹分析法（CWT），对运城市秋冬季大气PM2.5传输路径、对应重污染的天气形势和潜在源区进行分析。结果表明：（1）运城近地层盛行偏东风时污染频率高，弱的偏东风和西南风时，污染物浓度较大。秋冬季PM2.5后向轨迹西北方向最多达53.53%，偏东方向最少为11.25%，偏西方向和西南方向介于两者之间，分别为16.61%和12.06%。（2）不同轨迹对应天气形势不同，西北和偏西轨迹下，500 hPa高度场上为两槽一脊或偏西气流，700～850 hPa受脊前西北气流影响，地面为高压前底部型或均压场型；西南轨迹下，500 hPa高度场上为偏西气流，700～850 hPa运城处于槽前西南气流，地面气压场为高压前底部（底部）或均压场。（3）运城PM2.5潜在源区主要位于陕西南部、四川东部和新疆东南、甘肃的东南部等地区，说明影响运城秋冬季PM2.5的浓度除了来自汾渭平原西南部的颗粒物区域输送，来自西北方向新疆、甘肃的远距离颗粒物传输也是重要来源。 相似文献
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基于2013—2019年暖季新疆北部518个自动站逐时降水资料,运用常规统计、归一化及其偏离程度、降水集中度(PCD)和集中期(PCP)等方法,研究该区短时强降水(Flash Heavy Rain,FHR)时空分布和统计特征。结果表明:(1)近7 a新疆北部FHR发生频次年变化大,2016年最多,2014年最少,前者是后者的3.9倍。(2)FHR集中发生在6—7月,6月下旬为峰值,且日变化呈明显的单峰型,峰值主要在17:00—19:00。(3)FHR发生频次集中在山脉的迎风坡和喇叭口地形附近。(4)FHR PCD呈现由南向北、由西向东逐渐集中,阿勒泰地区最集中;PCP自伊犁河谷至天山北坡,从克拉玛依向西、向北逐渐推迟,阿勒泰地区最晚。(5)PCD伊犁河谷、天山北坡年变化呈增大的趋势,其它区域呈减小的趋势。PCP阿勒泰地区、博州、天山北坡年变化呈增大趋势,其它区域呈减小的趋势。 相似文献
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Paolo Laj Andrea I. Flossmann Wolfram Wobrock Sandro Fuzzi Giordano Orsi Loretta Ricci Stephan Mertes Alfons Schwarzenbck Jost Heintzenberg Harry Ten Brink 《Atmospheric Research》2001,58(4):256
We investigated the partitioning of trace substances during the phase transition from supercooled to mixed-phase cloud induced by artificial seeding. Simultaneous determination of the concentrations of H2O2, NH3 and black carbon (BC) in both condensed and interstitial phases with high time resolution showed that the three species undergo different behaviour in the presence of a mixture of ice crystals and supercooled droplets. Both H2O2 and NH3 are efficiently scavenged by growing ice crystals, whereas BC stayed predominantly in the interstitial phase. In addition, the scavenging of H2O2 is driven by co-condensation with water vapour onto ice crystals while NH3 uptake into the ice phase is more efficient than co-condensation alone. The high solubility of NH4+ in the ice could explain this result. Finally, it appears that the H2O2–SO2 reaction is very slow in the ice phase with respect to the liquid phase. Our results are directly applicable for clouds undergoing limited riming. 相似文献
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运用2013-2014年28个自动气象站的逐小时气温观测资料,分析了乌鲁木齐地区气温的日变化特征及季节特征。结果表明：1)城郊日最高气温出现频率最大的时次均为北京时间17时,出现频率在20%以上。日最低气温出现频率最大的时次为8时,频率在30%以上;2)年平均城郊气温差异即城市热岛强度在夜晚较大,早上7时左右达到最大,在1.5℃以上,白天较小,16时左右最小,仅有0.3℃左右;3)城郊日最高气温出现时间基本一致,但日最低气温出现时间有差别,冬季郊区最低气温出现滞后城区1小时,其他季节保持一致;4)城区逐小时城市热岛强度日内变化可分为三个阶段：8点到17点为下降时期,17点到22点为迅速上升时期,22点到第二天8点为稳定的强热岛时期;5)侯平均城市热岛强度年内变化,最大值发生在年终的第72候,为1.53℃,最小值发生在第秋末第67候,为0.33℃;6)综合来看,各季代表月平均城市热岛强度春季(4月)夜晚较强,夏季(7月)夜晚和白天都相对较弱,秋季(9月)夜晚最强,但白天最弱,甚至白天部分时刻(15到18点)出现了负值。冬季白天和晚上都比较强,是四季代表月份平均热岛强度最强的季节。 相似文献
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Predominantly in the context of Japan GMS-derived TBB data,study is undertaken of the relationship between the winter thermal conditions of the Qinghai-Xizang Plateau(QXP)and anomaly in Asian-Australian monsoons during northern summer.Evidence suggests that anti-correlation of cold air activity of East Asia with that of Mid Asia is responsible for the counterpart of the ground thermal characteristics anomaly on an interannual basis between the SW and NEQXP;the winter thermal pattern bears a closer correlativity with the subsequent summertime Asian-Australian monsoons anomaly;as the thermal distribution is reversed,so are the convection features over North and South China,maritime continent,the NW and SW Pacific at tropical and equatorial latitudes,resulting in vast difference between East-Asian summer and Indonesian-North Australian winter monsoons;the subtropical monsoon-associated rainbelt over the mid-lower Changjiang basins exhibits the discrepancy in vigor and northerly shift timing.Besides,part of the results has been further borne out through analysis of temperature and precipitation records of the eastern portion of the country in monsoon climate. 相似文献
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By HEATHER D. GRAVEN † BRITTON B. STEPHENS THOMAS P. GUILDERSON TERESA L. CAMPOS DAVID S. SCHIMEL J. ELLIOTT CAMPBELL RALPH F. KEELING 《Tellus. Series B, Chemical and physical meteorology》2009,61(3):536-546
Measurements of Δ14 C in atmospheric CO2 are an effective method of separating CO2 additions from fossil fuel and biospheric sources or sinks of CO2 . We illustrate this technique with vertical profiles of CO2 and Δ14 C analysed in whole air flask samples collected above Colorado, USA in May and July 2004. Comparison of lower tropospheric composition to cleaner air at higher altitudes (>5 km) revealed considerable additions from respiration in the morning in both urban and rural locations. Afternoon concentrations were mainly governed by fossil fuel emissions and boundary layer depth, also showing net biospheric CO2 uptake in some cases. We estimate local industrial CO2 :CO emission ratios using in situ measurements of CO concentration. Ratios are found to vary by 100% and average 57 mole CO2 :1 mole CO, higher than expected from emissions inventories. Uncertainty in CO2 from different sources was ±1.1 to ±4.1 ppm for addition or uptake of −4.6 to 55.8 ppm, limited by Δ14 C measurement precision and uncertainty in background Δ14 C and CO2 levels. 相似文献
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中国东部地区SO2, SO4=和HNO3(g)干沉降速度的季节变化 总被引：5，自引：0，他引：5
使用中国东部及其邻近地区各主要台站１９９２年全年００点和１２点（ＧＭＴ）地面及探空资料，由中尺度气象预报模式ＭＭ４产生中国东部地区地面以上大约４０ｍ高度（最低模式层）处二维温度、湿度和风场，使用污染物干沉降模块及该地区下垫面类型资料，计算出了该地区ＳＯ２，ＳＯ＝４和ＨＮＯ３（ｇ）全年干沉降速度的区域分布和季节变化。结果表明，由于受气象条件和下垫面类型的综合影响，３种污染物的干沉降速度有明显的变化。对ＳＯ２，全年区域平均极小值为０．０８８ｃｍ／ｓ，极大值为１．２７５ｃｍ／ｓ，平均值为０．４３０ｃｍ／ｓ；对ＳＯ＝４，分别为０．０１４ｃｍ／ｓ，０．２８７ｃｍ／ｓ和０．１１８ｃｍ／ｓ；对ＨＮＯ３（ｇ），分别为０．０６０ｃｍ／ｓ，５．２５０ｃｍ／ｓ和１．１２３ｃｍ／ｓ。ＳＯ２干沉降速度极大值分布在巴丹吉林沙漠和腾格里沙漠一带，对ＳＯ＝４和ＨＮＯ３（ｇ），除在上述沙漠地带有一极大值区域外，在靠近四川的云贵高原尚有另一极大区。对１９９２年全年来说，ＳＯ２和ＨＮＯ３（ｇ）干沉降速度极大值均出现在七月份，分别为０．５５２ｃｍ／ｓ和１．５１８ｃｍ／ｓ；而对ＳＯ＝４，干沉降速度极大值出现在九月份，其值为０．０９６ｃｍ／ｓ。这些值 相似文献
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Hiroshi A. Takahashi Eiichi Konohira Tetsuya Hiyama Masayo Minami Toshio Nakamura Naohiro Yoshida 《Tellus. Series B, Chemical and physical meteorology》2002,54(2):97-109
Diurnal variation in the atmospheric CO2 concentration and the carbon isotopic composition (Δ14 C and δ13 C) was measured in a forest in an urban area on 9 February 1999. The carbon isotope approach used in the present study differentiated between the quantitative contributions from anthropogenic and biogenic CO2 sources in the urban atmosphere. The anthropogenic (fossil fuel) and biogenic (soil respiration) contributions was estimated, and they ranged from 1 to 16% and from 2 to 8% of the total atmospheric CO2 . The diurnal variation of the anthropogenic CO2 was the major cause of the total atmospheric CO2 variation, while the biogenic CO2 remained relatively constant throughout the day. Estimating the contribution of soil respired CO2 provided the mean residence time of soil respired CO2 within the forest atmosphere. 相似文献