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1.
The parameters of heavily dusty air in an aerosol chamber under the conditions of an arid zone are studied. The transmission, optical density, Angstrom parameter, aerosol absorption coefficient, and visibility range are calculated. The temporal and spectral dependences of the optical parameters are analyzed. The regularities of the particle-size distribution function in strongly inhomogeneous dust aerosol are studied for coarsely (with a diameter more than 1 μm) and finely dispersed (with a diameter of less than 1 μm) fractions. The sizes and concentrations of the aerosol particles in air were determined using a photoelectric aerosol counter together with a 15-channel analyzer. We present the absorption spectra of coarsely and finely dispersed dust aerosol collected under different meteorological conditions. The possible mechanisms of variations in the aerosol disperse composition are analyzed.  相似文献   

2.
The Chinese desert is one of the major sources of atmospheric mineral dust transported for a long distance to the North Pacific by the atmospheric circulation. The characteristic of the aerosol in the North Pacific is smilar to that of the aerosol in North China with a considerable concentration of mineral in spring due to the large-scale dust storm occurring in North China. The study of isotope tracer indicates that the concentration of Al is significantly related to 210Pb, suggesting that the mineral aerosol in the North Pacific may origir ate from the desert in Northwest China by using air mass trajectory analysis. About 6-12×106 tons of Chinese desert mineral dust per year would be transported to the North Pacific.  相似文献   

3.
New prognostic estimates are obtained for the potential variability of the atmospheric ozone content in the first half of the 21st century. The calculations are based on models of gas composition and general circulation in the lower and middle atmosphere and on the scenarios of the World Meteorological Organization (WMO). It is shown that the rate of ozone content increase will be controlled to a considerable extent by variations in stratospheric temperature. Even though the contents of atmospheric chlorine and bromine are not reduced, contrary to the WMO prediction, and remain at the present-day levels, the continuation of stratospheric cooling will lead to a rapid recovery of the ozone content to its level characteristic of the 1980s. Model experiments on variations in the stratospheric aerosol content have shown that an increase in the aerosol concentration will not affect the rate of ozone recovery in the atmosphere during reduced emissions of chlorine and bromine gases if the stratospheric temperature remains lowered. Numerical experiments have also shown that the simultaneous anthropogenic action on the contents of halogen gases and on the lower-stratosphere temperature can reduce the adverse effects of Freons and halons on the ozone layer.  相似文献   

4.
Weekly aerosol samples were collected for two years from 1981 at six stations in the western North Pacific region. The samples were analyzed for aluminum to determine the mineral dust concentration in the air. By combining our data with observations in the central and eastern North Pacific by a US research group, the following results and conclusions have been obtained. Spring peaks in atmospheric mineral dust were observed at all the stations accompanied byKosa episodes (hazes due to mineral dust of Chinese origin). The spring peaks, however, varied from year to year. The mean concentration of mineral dust depends not only on the distance from the Asian coast but also on the latitude of the sampling station. The half-decrease distance of the atmospheric mineral dust turned out to be 500–600 km for all latitudes in the western North Pacific. This indicates that the rate of deposition of mineral dust in the western North Pacific is much larger than that in the central and eastern North Pacific.  相似文献   

5.
The results of 2-year (2010–2012) measurements of the concentrations of organic carbon (OC) and elemental carbon (EC), which were taken at the Zotino Tall Tower Observatory (ZOTTO) Siberian background station (61° N, 89° E), are given. Despite the fact that this station is located far from populated areas and industrial zones, the concentrations of OC and EC in the atmosphere over boreal forests in central Siberia significantly exceed their background values. In winter and fall, high concentrations of atmospheric carbonaceous aerosol particles are caused by the long-range transport (~1000 km) of air masses that accumulate pollutants from large cities located in both southern and southwestern regions of Siberia. In spring and summer, the pollution level is also high due to regional forest fires and agricultural burning in the steppe zone of western Siberia in the Russian–Kazakh border region. Background concentrations of carbonaceous aerosol particles were observed within relatively short time intervals whose total duration was no more than 20% of the entire observation period. In summer, variations in the background concentrations of OC closely correlated with air temperature, which implies that the biogenic sources of organic-particle formation are dominating.  相似文献   

6.
The results of studies of aerosol optical thickness (AOT) in Dushanbe conducted from July 2010 to March 2011 within the AERONET program are discussed. The statistical characteristics of AOT have been shown to significantly vary during dust intrusions. The seasonal variations in the dustiness of the atmosphere have been analyzed.  相似文献   

7.
A scheme of interpreting the data of two-wavelength lidar sounding is proposed. The scheme is based on functional relationships between the lidar ratios and between some integral characteristics of aerosol and the ratio of the backscattering coefficients at the sounding wavelengths. The AERONET data, results of contact aerosol measurements and multiwavelength lidar sounding, and the OPAC aerosol model are used to find these functional relationships, which are statistical in character. Analysis of data is made separately for continental, dust, oceanic, and smoke aerosols. Backscattering for mineral aerosol fractions are calculated for a model of randomly oriented spheroids. A numerical experiment shows that the errors in determining a number of integral parameters of aerosol (extinction coefficient, characteristic radius of particles, volume concentrations) that are due to the statistical straggling of lidar ratios and other specified integral characteristics are no greater than 32% if the optical thickness of the sounding layer is no greater than 1.  相似文献   

8.
This paper provides an overview of dust transport pathways and concentrations over the Arabian Sea during 1995. Results indicate that the transport and input of dust to the region is complex, being affected by both temporally and spatially important processes. Highest values of dust were found off the Omani coast and in the entrance to the Gulf of Oman. Dust levels were generally lower in summer than the other seasons, although still relatively high compared to other oceanic regions. The Findlater jet, rather than acting as a source of dust from Africa, appears to block the direct transport of dust to the open Arabian Sea from desert dust source regions in the Middle East and Iran/Pakistan. Dust transport aloft, above the jet, rather than at the surface, may be more important during summer. In an opposite pattern to dust, sea salt levels were exceedingly high during the summer monsoon, presumably due to the sustained strong surface winds. The high sea salt aerosols during the summer months may be impacting on the strong aerosol reflectance and absorbance signals over the Arabian Sea that are detected by satellite each year.  相似文献   

9.
Regularities in the effect of dust haze on the thermal regime of the air surface layer are revealed by examining air-temperature measurement data obtained at the Dushanbe, Termez, Bairam-Ali, Repetek, and Kurgan-Tyube meteorological stations. We find that the sharp decrease in daily air temperature and the slight increase in night temperature until the 1990s under strong dust storms leads to decreased temperatures in the air surface layer. Later, dust hazes of 3 to 8 days are more frequently observed with a pulsating change in the horizontal range of visibility. Depending on their power, these hazes lead to either heating or cooling of the atmospheric surface layer.  相似文献   

10.
ＴｈｅｃｈｅｍｉｃａｌｃｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆａｅｒｏｓｏｌｓｉｎｔｈｅＫｕｒｏｓｈｉｏａｒｅａ－Ⅰ．Ｓｏｕｒｃｅｓａｎｄｆｌｕｘｅｓ￥ＣｈｅｎＬｉｑｉ；ＹａｎｇＸｕｌｉｎ；ＴａｎｇＲｏｎｇｋｕｎａｎｄＹｕＱｕｎ＇（ＲｅｃｅｉｖｅｄＦｅｂｒ...  相似文献   

11.
The studies conducted in 1991–2004 by scientists of the A.M. Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences, and the Karpov Institute of Physical Chemistry yielded data on the structures of the surface air layer (to a height of 20 m) and both subinversion and inversion layers (to heights of from 800 m to 1 km), where arid aerosol is transported. One of the main objectives of the 2007 experiment was to record the space-vortex structures within a layer of 30–700 m that directly provide the removal and long-range transport of fine-dispersed (<5 µm) desert aerosol. This paper describes the organization of the Khar-Gzyr 2007 experiment (Black Lands, 2007) to study the convective removal of arid aerosol from desertificated lands, and it presents some data obtained from the remote sensing of the atmospheric boundary layer with a sodar network in the course of this experiment. The sodar network, which was developed to study a spatial structure of coherent vortices, included three identical minisodars (with carrier frequencies of 3.8 kHz) located at the apices of a triangle, each side of which was about 3.5 km, and a sodar (with a carrier frequency of 1.7 kHz). The vertical profiles of the three wind-velocity components and the characteristics of air temperature fluctuations were determined. The procedure of identifying coherent vortex structures is described. The variations in the vertical and horizontal wind-velocity components and the scales characteristic of such structures are estimated.  相似文献   

12.
2001年春季在青岛采集了3次沙尘暴过境时的大气气溶胶粒子，并利用单个气溶胶粒子分析方法对沙尘粒子含有硫酸盐和硝酸盐的状况进行了分析研究。结果发现3％～13％的沙尘粒子含有硫酸盐，6％～10％的沙尘粒子含有硝酸盐。这些比例远小于无沙尘时北京、青岛等城市污染大气中矿物粒子所含这些成分的比例，表明沙尘粒子在从内陆源区传输到沿海地区的过程中对大气中硫酸盐和硝酸盐生成的促进作用远不如城市污染大气中的矿物粒子明显。  相似文献   

13.
The results of measurements of the total content of carbon monoxide in an atmospheric column over Moscow and the Zvenigorod Scientific Station (ZSS) are given for the period 1993–2005. The simultaneous measurements of the regional background contents of carbon monoxide over a rural area (ZSS) and over Moscow made it possible to isolate an urban portion of the CO content. The total content of CO over the city varies significantly from day to day from values close to the background value to values that are 2.5–3 times greater than the background value. The number of days with such a CO content is 5% of the total number of measurement days. Such a CO content is most often observed during the cold seasons. During the warm seasons, in most of the cases, slight excesses of the CO background value are observed in the urban atmosphere. Variations in the CO content are determined mainly by wind-velocity variations and temperature inversions. In 2002, the high CO concentrations were due to forest and peatbog fires. On some days, over the ZSS, the concentrations of CO were high as never before. Over this period (12 years), the CO content in the surface air layer over the city did not increase.  相似文献   

14.
An instrumented balloon launched from Kiruna during the SESAME experiment displayed simultaneous local decreases of water vapor and aerosol at 2 different potential temperature levels 410 K and 364 K. Despite the similar characteristics present at both levels, 2 different explanations are given for these laminae. At the highest level, the air mass showing the water vapor and aerosol decrease is found when the balloon travels in the vortex edge region. A back trajectory shows that this air mass was trapped in the vortex edge region for several days and processed by a PSC causing the water vapor and aerosol decreases. On the other hand, the lowest level air mass was found to be in the sub‐vortex region. No local conditions can explain the observed decreases of water vapor and aerosol. Back trajectories show that this air mass originates from middle latitudes. Although the back trajectories calculated in these conditions are more subject to caution, comparison of several characteristics at the measurement point and at the middle latitude sites corroborates the explanation of the decrease of water vapor and aerosol by the origin of the air mass.  相似文献   

15.
Quasi-biennial variations in vertical profiles of ozone, temperature, air pressure, and zonal and meridional wind velocities are analyzed from ozonesonde data obtained at the western European stations of Lindenberg, Hohenpeissenberg, and Payerne. The effect of quasi-biennial variations manifests itself variously in different variables and is nonuniform in altitude. The period of quasi-biennial variations is not constant, and the values of the mean period group mainly around 2 and 2.5 years. As in the North American region, the effects of quasi-biennial variations in different parameters of the stratosphere and troposphere over western Europe are due to a combination of the effects of the quasi-biennial oscillation (QBO) in the equatorial stratosphere, the El Niño-Southern Oscillation (ENSO), and the North Atlantic Oscillation (NAO). The observed 2.5-year variations in stratospheric ozone are related to the equatorial QBO to a larger extent in comparison with variations in other variables. It seems likely that a determining influence on variations in stratospheric wind and temperature is exerted by the ENSO. Variations in tropospheric and stratospheric parameters with a mean period of about 2 years are due to the ENSO and NAO effects.  相似文献   

16.
The influence of increased concentrations of submicron aerosol produced by forest fires on thermal characteristics of the atmospheric boundary layer (ABL) in Moscow and its remote vicinity (the town of Zvenigorod) are analyzed on the basis of regular remote measurements of the ABL temperature profile with the use of MTP-5 profilers. In the air basin of a large city, additional aerosol and accompanying pollutants in early morning hours (at small heights of the Sun) most frequently did not cause substantial changes in the ABL thermal structure. In the locality remote from the megalopolis (Zvenigorod), the atmospheric pollution by aerosol led to noticeable changes in the ABL thermal characteristics. Especially strong changes were observed in the daytime, during the maximum supply of solar radiation. In morning hours, the heating rate of the lower 100-m layer of the polluted air exceeded the heating rate of a relatively pure air by more than one degree. In higher layers, the differences between the rates of temperature changes in a relatively clean atmosphere and in an atmosphere polluted by aerosol (in the suburb) were insignificant.  相似文献   

17.
通过与地基气溶胶观测数据的对比,确认了SeaWiFS气溶胶光学厚度产品用于研究中国海域气溶胶分布和变化特征的有效性。在此基础上,分析了中国海域气溶胶光学厚度的季节变化和地理分布特征。研究结果表明,中国东部海域平均气溶胶光学厚度存在以中纬度为中心的纬向分布;受沙尘、季风气候的影响,中国海域气溶胶光学厚度存在季节变化,不同海区有不同的季节变化和分布特征。渤海、黄海及东海有类似的变化特征,春季都受到沙尘气溶胶的影响,使中国东部海域气溶胶光学厚度普遍高于0.160,且对东海的影响最大;夏、秋季逐渐减小,冬季有所回升。南海气溶胶光学厚度均值为0.150,随时间变化不明显,但地理分布变化显著;受季风气候的影响,从春季到冬季,气溶胶光学厚度高值中心从高纬海域向低纬海域转移,范围也逐渐扩大。冬季南海大部分海域气溶胶光学厚度都达到0.160以上,是整个中国海域冬季气溶胶光学厚度最大的海区。气溶胶光学厚度的季节变化和地理分布特征为研究中国海区域气候变化和海洋生态提供了依据。  相似文献   

18.
The influence of a solar eclipse on solar-radiation fluxes, meteorological parameters, turbulence characteristics, and vertical temperature profiles in the atmospheric boundary layer is analyzed. Air-temperature variations caused by an eclipse and time delays of these variations with respect to the onset of the total-eclipse phase in the atmospheric surface and boundary layers are determined. The influence of a solar eclipse on the turbulent kinetic energy, turbulent heat flux, and variance and spectral density of the power of air-temperature pulsations are estimated. Variations in aerosol parameters and concentrations of light ions during a total solar eclipse are discussed.  相似文献   

19.
The results of an analysis of intraweek differences in surface temperature precipitation, and optical aerosol thickness (τ550) in Moscow and in the vertical profiles of air temperature and wind over central Russia within the 2000–2009 period are given. The relation between the weekly cycles of the meteorological parameters and those of anthropogenic pollutions and dynamic processes is studied.  相似文献   

20.
Data are presented for the concentrations of Al, Fe, Mn, Ni, Co, Cr, V, Cu, Zn, Pb and Cd in aerosols collected over two contrasting regions of the Indian Ocean. These are: (1) the northern Arabian Sea (AS), from which samples were collected in the northeast monsoon, during which the region receives an input of crustal material from the surrounding arid land masses; and (2) the Tropical Southern Indian Ocean (TSIO), a remote region from which samples were collected from air masses for which there were no large-scale up-wind continental aerosol sources. The TSIO samples can be divided into two populations: Population I aerosols, collected from air masses which have probably impinged on Madagascar, and Population II aerosols, which have been confined to open-ocean regions to the south of the area.The data indicate that there are strong latitudinal variations in the chemical signatures of aerosols over the Indian Ocean. The input of crustal material to the Arabian Sea gives rise to an average Al concentration of about 1000 ng m−3 of air in the northeast monsoon regime. As a result, the concentrations of all trace metals are relatively high, and the values of crustal enrichment factors are less than 10 for most metals, in the AS aerosols. In contrast, TSIO Population II ‘open-ocean southern air’ sampled during the southwest monsoon season, has an average Al concentration of only about 10 ng m−3 of air. Trace metal concentrations in the TSIO ‘open-ocean southern air’ during the southwest monsoon season are representative of ‘clean’ remote marine air and are generally similar to those reported over the central North Pacific.Mineral dust concentrations over the Indian Ocean decrease in a north to south direction, from about 15–20 μg m−3 of air in the extreme north to about 0.01–0.25 μg m−3 of air in the far south. The deposition of mineral dust over the northern Arabian Sea can account for approximately 75% of the non-carbonate material incorporated into the underlying sediments.In the Arabian Sea the dissolved atmospheric inputs of all the trace metals, with the exception of Cu and Co, exceed those from fluvial run-off by factors which range from 9.6 for Pb to 1.6 for Cr.  相似文献   

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