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991.
吸收性气溶胶指数AAI(Absorbing Aerosol Index)是基于卫星观测的紫外后向散射辐射导出的参数,与大气中对紫外线有吸收作用的气溶胶(简称吸收性气溶胶)有关,能够定性反应吸收性气溶胶的存在与空间分布特征。由于臭氧在AAI反演波段对紫外线仍然存在弱吸收作用,因此AAI可能与大气臭氧总量有关,臭氧反演的误差也可能对AAI的反演精度造成影响。为了研究臭氧总量与AAI的关系,臭氧反演的精度对AAI反演的影响,利用辐射传输模型通过敏感性实验,来模拟吸收性气溶胶指数和臭氧总量之间的关系,臭氧反演误差对吸收气溶胶指数的反演的影响。采用沙漠气溶胶,不改变气溶胶的含量,通过改变中纬度夏季的臭氧总量来计算大气模型。对臭氧总量、气溶胶含量与AAI的内在关系,臭氧总量对AAI反演精度的影响进行了模拟,模拟结果表明,气溶胶指数与臭氧总量的改变存在正相关关系,而臭氧总量的反演误差对AAI指数的反演影响不大。基于风云三号气象卫星紫外臭氧总量探测仪(FY-3/TOU)的臭氧总量和吸收性气溶胶指数数据(2012年),分析了青藏高原地区7月份臭氧总量与吸收性气溶胶指数空间分布特征的关系,与模拟结果一致。  相似文献   
992.
利用2014年夏季在河北饶阳开展的“华北区域光化学立体试验”观测得到气溶胶辐射特性,根据三波长角散射浊度仪Aurora 4000测量获取的前向角散射系数(10°~90°)和后向散射系数,提出了一种基于浊度仪直接测量的气溶胶角散射系数和改进的HG相函数近似获取气溶胶散射相函数、不对称因子的拟合估算方法。分析了2014年6月16日—8月18日夏季观测试验期间河北饶阳地区大气气溶胶细粒子(PM2.5)在635 nm,525 nm,450 nm 3个波段的不对称因子、相函数等的变化特征。结果表明:用改进的HG相函数近似能够较好地拟合河北饶阳实际观测的PM2.5的气溶胶散射相函数。拟合得到河北饶阳地区观测期间干气溶胶细粒子在3个波段的平均不对称因子(g)分别为0.53±0.04(635 nm),0.57±0.05(525 nm)和0.57±0.07(450 nm)。  相似文献   
993.
南极地区提供了地球上最好的研究气溶胶的背景组成场所,为此,我们用八级阶式撞击采样器采集了不同粒径的样品。采样于1986年间在南极中国长城站进行,样品分析方法是质子激发X射线发射法(PIXE)。为了研究不同元素的富集因子,将全部结果分为两组,粒径大于10/μm粒子为粗粒,小于10/μm的粒子为细粒,并且还讨论了粗、细粒中各元素的相关因子,长城站气溶胶所测元素结果与其他地区采样点所测结果作了比较,证明南极地区是地球上良好的背景地区。  相似文献   
994.
利用MODIS-GOCART同化的2001年逐月气溶胶光学厚度资料,在修改区域气候模式RegCM2辐射方案的基础上,连续积分5年获得平均的中国东部地区气溶胶短波和长波直接辐射效应,并通过数值试验研究了气溶胶垂直分布对辐射强迫及其气候响应的影响。结果表明:气溶胶的短波辐射效应能冷却地表、加热大气;长波辐射效应能加热地表、冷却大气;大气顶净辐射强迫年平均为-4.1W/m^2;辐射强迫绝对值在春季最大,夏季次之,冬季最小;模拟区域中最大辐射强迫值主要位于华北、华南地区及四川盆地;气溶胶垂直分布是影响气溶胶辐射强迫的重要因素。总体上气溶胶层越靠近地面,大气顶辐射强迫绝对值越大,地表辐射强迫绝对值越小,大气顶辐射强迫对垂直分布较敏感;气候系统的反馈作用会放大气溶胶垂直分布对辐射气候效应的影响。  相似文献   
995.
在辐射传输模式CRM中引入粒径为0.5、1.0、2.0、4.0、8.0 μm的5段矿尘气溶胶粒子,模拟计算气溶胶对短波辐射通量的影响.计算结果表明:气溶胶引起晴空短波净辐射通量减少;在分布有气溶胶的层内,粒子半径增大、光学厚度增大都会使短波净辐射通量减少;在气溶胶层以上,辐射通量的变化与具体的粒子半径有关.  相似文献   
996.
华南准静止锋暖区内降水的物理化学特征   总被引:8,自引:0,他引:8  
吴兑  甘春玲  陈位超  游积平 《气象》1994,20(2):18-24
介绍了一次华南准静止暖区内降水的物理化学特征的综合观测分析结果。主要有:①暖区内积云降水雨滴浓度不高,但滴径较大,谱型以多峰谱为主;②雨水pH值较低,平均4.43,离子成分中NO3,Cl,SO4,NH^+4,Na^+的浓度较高;③本次降水清除了气溶胶总质量的45%,对Cl,F,NO3的清除率较高;④由于气溶胶中阴离子被雨水清除的效率较高(主要是NO3)而阳离子的清除率低,致使雨水pH值下降,这可能  相似文献   
997.

Book Reviewed in this article:

Latin America: Case Studies. Richard G. Boehm and Sent Visser

Locality and Rurality: Economy and Society in Rural Regions. Tony Bradley And Philip Lowe

The City and the Grassroots. Manuel Castells

Geopolitics and Conflict in South America. Quarrels among Neighbors. Jack Child

Post-Industrial America: A Geographical Perspective. David Clark

Coastal Research: UK Perspectives. Malcolm W. Clark

A Rural Policy for the EEC? Hugh Clout

Peasant Agriculture in Assam: A Structural Analysis. M. M. Das.

Environmental Change and Tropical Geomorphology. I. Douglas and T. Spencer

Advances in Abandoned Settlement Analysis: Application to Prehistoric Anthrosols in Colombia, South America. Robert C. Eidt

Measuring Culture. Jonathan L. Gross and Steve Rayner

North America: A Human Geography. Paul Guinness and Michael Bradshaw

A Geographical Bibliography for American Libraries. Chauncy D. Harris et al.

Geography and the Urban Environment: Progress in Research and Applications, Vol. VI. D. T. Herbert and R. J. Johnston

Changes in Global Climate: A Study of the Effect of Radiation and Other Factors During the Present Century. K. Ya. Kondrat'ev.

Rural Development and the State: Contradictions and Dilemmas in Developing Countries. David A. M. Lea and D. P. Chaudhri

The Martial Metropolis: U.S. Cities in War and Peace. Roger W. Lotchin

The Climate of the Earth. Paul E. Lydolph.

Weather and Climate. Paul E. Lydolph.

Spatial Divisions of Labor: Social Structures and the Geography of Production. Doreen Massey.

Panorama of the Soviet Union. N. Mikhailov.

Soviet Armenia. K. S. Demirchian.

USSR: Geography of the Eleventh Five-Year Plan Period. K. Spidchenko.

Planung und Verwirklichung der Wiener Ringstrassenzone (Planning and Materialization of the Ringstrasse-Zone of Vienna). Kurt Mollik, Hermann Reining, Rudolf Wurzer.

The American West Transformed: The Impact of the Second World War Gerald D. Nash.

An Overview of the Survey of Income and Program Participation. Dawn Nelson, David McMillen, and Daniel Kasprzyk.

Phenomenology, Science and Geography: Spatiality and the Human Sciences. John Pickles.

Biological Diversification in the Tropics. Ghillean T. Prance

Die Wanderviehwirtschaft im gebirgigen Westen der U.S.A. und ihre Auswirkungen im Naturraum. Gisbert Rinschede.

Social and Economic Aspects of Radioactive Waste Disposal: Considerations for Institutional Management

World-Wide Weather. K. Takahashi

Coastal Geomorphology in Australia. B. G. Thom

Settlement System in Rural India: A Case Study of the Lower Ganga-Yamuna Doab. Ram Chandra Tiwari.

Computer Programming for Geographers. David J. Unwin and John A. Dawson.

Late Quaternary Environments of the Soviet Union. A. A. Velichko, ed. H. E. Wright, Jr. and C. W. Barnosky

Ethics in Planning. Martin Wachs  相似文献   
998.
Nighttime volume emission rates and rotational temperatures, obtained from simultaneous observations of molecular oxygen and hydroxyl airglow at Almaty (43.25°N, 76.92°E) and Sierra-Nevada (37.2°N, 356.7°E), along with ionospheric density derived from foF2 in the vertical sounding ionograms over Almaty are analysed to study the variability and coupling of parameters observed in the upper mesosphere and ionosphere during the period of February - April, 2000.Ionospheric critical frequency measurements and airglow observations by the Mesopause Rotational Temperature Imager (MORTI) at Almaty and the Spectral Airglow Temperature Imager (SATI) at Sierra-Nevada Observatories show an increase in long-period planetary wave (PW) activity from the end of February until the middle of March, 2000.Very good agreement was found in the temporal variations of emission rates and rotational temperatures from March 1-15, 2000 measured at the Almaty and Sierra-Nevada sites. Similar perturbations could also be seen in the ionospheric critical frequency (ΔfoF2) obtained as a difference between current foF2 values and an ionospheric background level.The perturbations observed have been interpreted employing the Met office stratospheric model results. Latitudinal structure of a quasi 5-day wave was identified, for which the first-symmetric-mode amplitude and symmetric behaviour of phase are in good agreement with theoretical prediction. The analysis of the Met office stratospheric data indicate the presence of westward-propagating PW with periods of ∼5 and 10 days during the period of interest. The temporal correlation between planetary scale oscillations observed in the datasets examined (ionospheric, optical and meteorological) suggest dynamical coupling with the stratosphere. A negative disturbance in ΔfoF2 of ∼25% observed 1 day before a sharp increase in the MORTI mesospheric rotational temperature registered on March 10 at Almaty, is also discussed in the context of the possible stratosphere/mesosphere/ionosphere coupling.  相似文献   
999.
根据2013年10月13、14日共4个架次机载气溶胶探测资料及宏观天气资料,分析了飞机爬升阶段河北地区气溶胶数浓度、平均直径在降水前后的垂直变化特征,研究了不同高度的粒子谱特征,并且尝试对一次典型层状云过程中云内、云底的气溶胶粒子谱进行了拟合。结果表明:1)降水前和降水过程中粒子平均浓度变化不大,降水结束后,粒子浓度显著减小。2)气溶胶粒子浓度、平均直径受云和逆温的影响十分明显。存在逆温时,逆温层附近气溶胶粒子浓度显著增大,粒子浓度曲线与逆温层温度曲线一致;无逆温层时,粒子数浓度随高度呈负指数递减。低空的气溶胶粒子大小受逆温层影响较小,高空的粒子大小变化幅度较大,且多呈单峰或多峰分布。3)对爬升阶段每500 m进行平均,得到不同高度的粒子谱基本呈单峰或双峰分布,单峰分布峰值在细粒子端,双峰分布则在粗、细粒子端各有一峰值。4)此次观测得到的层状云内气溶胶粒子数浓度曲线用负指数函数拟合效果更好,层状云云底和云中拟合谱中参数λ变化可以忽略,参数A值变化较大。  相似文献   
1000.
This study investigated the drivers and physical processes for the abrupt decadal summer surface warming and increases in hot temperature extremes that occurred over Northeast Asia in the mid-1990 s. Observations indicate an abrupt increase in summer mean surface air temperature(SAT) over Northeast Asia since the mid-1990 s. Accompanying this abrupt surface warming, significant changes in some temperature extremes, characterized by increases in summer mean daily maximum temperature(Tmax), daily minimum temperature(Tmin), annual hottest day temperature(TXx), and annual warmest night temperature(TNx) were observed. There were also increases in the frequency of summer days(SU) and tropical nights(TR).Atmospheric general circulation model experiments forced by changes in sea surface temperature(SST)/ sea ice extent(SIE),anthropogenic greenhouse gas(GHG) concentrations, and anthropogenic aerosol(AA) forcing, relative to the period 1964–93, reproduced the general patterns of observed summer mean SAT changes and associated changes in temperature extremes,although the abrupt decrease in precipitation since the mid-1990 s was not simulated. Additional model experiments with different forcings indicated that changes in SST/SIE explained 76% of the area-averaged summer mean surface warming signal over Northeast Asia, while the direct impact of changes in GHG and AA explained the remaining 24% of the surface warming signal. Analysis of physical processes indicated that the direct impact of the changes in AA(through aerosol–radiation and aerosol–cloud interactions), mainly related to the reduction of AA precursor emissions over Europe, played a dominant role in the increase in TXx and a similarly important role as SST/SIE changes in the increase in the frequency of SU over Northeast Asia via AA-induced coupled atmosphere–land surface and cloud feedbacks, rather than through a direct impact of AA changes on cloud condensation nuclei. The modelling results also imply that the abrupt summer surface warming and increases in hot temperature extremes over Northeast Asia since the mid-1990 s will probably sustain in the next few decades as GHG concentrations continue to increase and AA precursor emissions over both North America and Europe continue to decrease.  相似文献   
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