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1.
《Atmospheric Research》2007,83(3-4):643-651
For a better understanding of urban aerosols, sun/sky photometry has been undertaken at the Kinki University campus in Higashi-Osaka as a NASA/AERONET station since 2002. A new instrument, the SPM-613D (Kimoto Electric), has been taking measurements at the same site since March 15, 2004. The relationship between aerosol properties obtained from radiometry with AERONET and the SPM measurements is examined. It is found that there is a linear correlation between SPM concentrations and aerosol properties, which indicates that aerosol characteristics can be estimated from SPM data, and vice versa.It is also shown that the air quality of the Higashi-Osaka site is poor due to not only the anthropogenic particles by local emissions, such as diesel vehicles and chemical industries, but also due to the dust particles coming from continental desert areas by large scale climatic conditions. 相似文献
2.
The Moderate Resolution Imaging Spectroradiometer(MODIS) sensor onboard NASA's Aqua satellite has been collecting valuable data about the Earth system for more than 14 years, and one of the benefits of this is that it has made it possible to detect the long-term variation in aerosol loading across the globe. However, the long-term aerosol optical depth(AOD)trends derived from MODIS need careful validation and assessment, especially over land. Using AOD products with at least 70 months' worth of measurements collected during 2002–15 at 53 Aerosol Robotic Network(AERONET) sites over land,Mann–Kendall(MK) trends in AOD were derived and taken as the ground truth data for evaluating the corresponding results from MODIS onboard Aqua. The results showed that the AERONET AOD trends over all sites in Europe and North America, as well as most sites in Africa and Asia, can be reproduced by MODIS/Aqua. However, disagreement in AOD trends between MODIS and AERONET was found at a few sites in Australia and South America. The AOD trends calculated from AERONET instantaneous data at the MODIS overpass times were consistent with those from AERONET daily data, which suggests that the AOD trends derived from satellite measurements of 1–2 overpasses may be representative of those from daily measurements. 相似文献
3.
M. Chaâbane M. Masmoudi K. Medhioub F. Elleuch 《Meteorology and Atmospheric Physics》2006,92(1-2):103-114
Summary Spectral aerosol optical thickness have been measured at Thala site (central West of Tunisia) from March to October 2001.
The measurement site is located in a continental and non industrialized region, approximately 150 km from the North coast
of the Mediterranean Sea and nearby the Algerian border. Thala site could be then influenced by the dust content of the continental
air masses carried by western and southern winds. A second pollution source is constituted by industrial and/or maritime particles
carried by northern and eastern winds. AOT measurements acquired through the ground-based AERONET are analyzed. The diurnal
cycle over Thala and two other areas within the network showed various trends and a prevailing pattern of the optical thickness
increase by 10–40% during the day. Daily AOT and monthly averaged aerosol optical thickness, ?ngstr?m coefficient and precipitable
water vapor are computed and compared with those of other sites. Measured meteorological parameters represent a valuable supplement
to the data sets with the sunphotometer measurements. The analysis of the results shows that there is a high correlation between
aerosol optical properties (AOT and ?ngstr?m coefficient) and the local weather conditions, essentially wind speed and direction
and air specific humidity. 相似文献
4.
以我国MODIS共享网站积累的MODIS L1B数据和美国威斯康辛大学提供的IMAPP软件包气溶胶产品软件为基础, 经过产品运行本地化改进处理, 在国家卫星气象中心建立了气溶胶产品业务化生成和发布机制。为支持气溶胶遥感产品算法改进以及潜在用户对产品的合理应用, 给出对国家卫星气象中心运行的MODIS气溶胶遥感产品质量检验分析结果。利用2005年1月— 2007年5月AERONET地基气溶胶监测网的L2.0级气溶胶光学厚度产品作为真值, 用它匹配MODIS陆上气溶胶光学厚度产品开展检验。检验结果表明:以卫星过境前后30min地基观测时间平均值匹配地基站点位置10 km半径范围内的卫星反演结果空间平均值开展检验, 总体样本的气溶胶光学厚度均方根误差约为0.25;满足产品误差要求 (±0.05±0.20τ) 的样本占总样本数的44%; 气溶胶光学厚度反演结果精度具有季节和地域差异, 干季(秋、冬、春)的气溶胶光学厚度误差较小, 而雨季气溶胶光学厚度误差较大, 云是雨季气溶胶光学厚度反演结果误差较大的主要影响因素。 相似文献
5.
Thierry Elisas Claude Devaux Philippe Goloub Maurice Herman 《Tellus. Series B, Chemical and physical meteorology》2000,52(2):620-635
Measurements of the polarisation state of the atmosphere were performed at Tenerife in June–July 1997, in the framework of ACE‐2 (second Aerosol Characterization Experiment), by 2 ground‐based instruments: RefPol (a LOA prototype) which took measurements at 445, 665, 870, 1610 nm in the solar principal plane; and an automatic CIMEL (CE 318) sun/sky‐photometer which measured polarised radiation at 870 nm in the same observational geometry. Measurements acquired during the campaign, as well as AERONET (AErosol RObotic NETwork) measurements acquired at the sites of Cape Verde and M'Bour, are processed with an algorithm determining the polarised single‐scattering sky‐radiance due to aerosols, directly proportional to the aerosol polarised phase function (representing the probability to scatter polarised radiation in the direction of the scattering angle). A good correlation between the Ångström exponent α, representing the spectral dependence of the extinction measurements, and the polarised phase function is observed on each set of data. The uncertainty of retrievals at 445 nm makes the determination of the spectral dependence of polarisation inconclusive but does not prevent confirming the dependence of the aerosol polarised phase function on α, at all wavelengths. An Ångström exponent of 1 corresponds to a polarised phase function of around 0.1 (±0.04), at 870 nm and at a scattering angle of 60°. For α between 0 and 0.4, the average value of the polarised phase function is 0.05. The correlation shows that polarisation is more sensitive to small particles than to large particles. The discrepancy between retrievals and Mie calculations from an AERONET size distribution, inverted from Izaña measurements acquired during a dust event, suggests the presence of small particles, not detected by total sky‐radiance measurements. 相似文献
6.
Aerosol optical properties over Beijing and Xianghe under several typical weather conditions
(clear sky, light haze, heavy pollution and dust storm) are derived from POLDER (POLarization and
Directionality of the Earths Reflectances)/PARASOL (Polarization and Anisotropy of Reflectances for
Atmospheric Sciences coupled with Observations from a Lidar) multi-directional, multi-spectral polarized
signals using a more reliable retrieval algorithm as proposed in this paper. The results are compared with
those of the operational retrieval algorithm of POLDER/PARASOL group and the ground-based AERONET (AErosol
RObotic NETwork)/PHOTONS (PHOtometrie pour le Traitement Operational de Normalisation Satellitaire)
measurements. It is shown that the aerosol optical parameters derived from the improved algorithm agree well
with AERONET/PHOTONS measurement. The retrieval accuracies of aerosol optical thickness (AOT) and effective
radius are 0.06 and 0.05 mu m respectively, which are close to or better than the required accuracies (0.04
for AOT and 0.1 mu m for effective radius) for estimating aerosol direct forcing. 相似文献
7.
利用AERONET观测资料从气候学的角度比较分析了2001-2011年东亚地区沙尘天气发生时沙尘源区和下游区大气气溶胶光学特性。结果表明：沙尘期间沙尘源区气溶胶光学厚度明显大于下游区,而Angstr?m波长指数却小于下游区,当沙尘暴出现时会降至零甚至负值。气溶胶粒子尺度体积谱分布除敦煌为单峰外,其余各站均呈双峰分布,香河和北京的细粒子浓度明显大于西北地区,这可能是由细的沙尘粒子和污染气溶胶共同造成。在440-1020 nm范围内,中国地区气溶胶单次散射反照率平均值为0.93,韩国和日本站分别为0.93和0.94。沙尘源区与下游区相比,复折射指数实部偏大,虚部偏小。总体来说,沙尘天气下东亚地区在4个波段内平均不对称因子为0.70。 相似文献
8.
S. Gonzi O. Dubovik D. Baumgartner E. Putz 《Meteorology and Atmospheric Physics》2007,96(3-4):277-291
Summary One of the great unknowns in climate research is the contribution of aerosols to climate forcing and climate perturbation.
In this study, retrievals from AERONET are used to estimate the direct clear-sky aerosol top-of-atmosphere and surface radiative
forcing effects for 12 multi-site observing stations in Europe. The radiative transfer code sdisort in the libRadtran environment is applied to accomplish these estimations. Most of the calculations in this study rely on observations which
have been made for the years 1999, 2000, and 2001. Some stations do have observations dating back to the year of 1995. The
calculations rely on a pre-compiled aerosol optical properties database for Europe. Aerosol radiative forcing effects are
calculated with monthly mean aerosol optical properties retrievals and calculations are presented for three different surface
albedo scenarios. Two of the surface albedo scenarios are generic by nature bare soil and green vegetation and the third relies on the ISCCP (International Satellite Cloud Climatology Project) data product. The ISCCP database has
also been used to obtain clear-sky weighting fractions over AERONET stations. The AERONET stations cover the area 0° to 30° E
and 42° to 52° N. AERONET retrievals are column integrated and this study does not make any seperation between the contribution
of natural and anthropogenic components. For the 12 AERONET stations, median clear-sky top-of-atmosphere aerosol radiative
forcing effect values for different surface albedo scenarios are calculated to be in the range of −4 to −2 W/m2. High median radiative forcing effect values of about −6 W/m2 were found to occur mainly in the summer months while lower values of about −1 W/m2 occur in the winter months. The aerosol surface forcing also increases in summer months and can reach values of −8 W/m2. Individual stations often have much higher values by a factor of 2. The median top-of-atmosphere aerosol radiative forcing
effect efficiency is estimated to be about −25 W/m2 and their respective surface efficiency is around −35 W/m2. The fractional absorption coefficient is estimated to be 1.7, but deviates significantly from station to station. In addition,
it is found that the well known peak of the aerosol radiative forcing effect at a solar zenith angle of about 75° is in fact
the average of the peaks occurring at shorter and longer wavelengths. According to estimations for Central Europe, based on
mean aerosol optical properties retrievals from 12 stations, the critical threshold of the aerosol single scattering albedo,
between cooling and heating in the presence of an aerosol layer, is close between 0.6 and 0.76. 相似文献
9.
Sungkyun SHIN Young Min NOH Kwonho LEE Hanlim LEE Detlef MLLER Y.J.KIM Kwanchul KIM Dongho SHIN 《大气科学进展》2014,31(6):1417-1426
The vertical distribution of single scattering albedos （SSAs） of Asian dust mixed with pollutants was derived using the multi-wavelength Raman lidar observation system at Gwangju （35.10°N,126.53°E）.Vertical profiles of both backscatter and extinction coefficients for dust and non-dust aerosols were extracted from a mixed Asian dust plume using the depolarization ratio from lidar observations.Vertical profiles of backscatter and extinction coefficients of non-dust particles were input into an inversion algorithm to retrieve the SSAs of non-dust aerosols.Atmospheric aerosol layers at different heights had different light-absorbing characteristics.The SSAs of non-dust particles at each height varied with aerosol type,which was either urban/industrial pollutants from China transported over long distances at high altitude,or regional/local pollutants from the Korean peninsula.Taking advantage of independent profiles of SSAs of non-dust particles,vertical profiles of SSAs of Asian dust mixed with pollutants were estimated for the first time,with a new approach suggested in this study using an empirical determination of the SSA of pure dust.The SSAs of the Asian dust-pollutants mixture within the planetary boundary layer （PBL） were in the range 0.88-0.91,while the values above the PBL were in the range 0.76-0.87,with a very low mean value of 0.76 ± 0.05.The total mixed dust plume SSAs in each aerosol layer were integrated over height for comparison with results from the Aerosol Robotics Network （AERONET） measurements.Values of SSA retrieved from lidar observations of 0.92 ± 0.01 were in good agreement with the results from AERONET measurements. 相似文献
10.
《Atmospheric Research》2005,73(3-4):173-201
We summarise the microphysical and optical parameters of some principal aerosol species obtained by instrumentation on the UK Met Office C-130 aircraft during international field campaigns since 1996. The aerosol species include Saharan dust, biomass burning aerosol, European continental pollution, eastern seaboard USA pollution, and clean maritime aerosol. The typical structure of the aerosol in the vertical from each airmass type is described. Microphysical parameters are described that comprise the mode radius and geometric standard deviation associated with 2–3 lognormal fits to the mean observed aerosol size distributions spanning the accumulation and coarse modes. Optical parameters comprising the aerosol single scattering albedo (which was both measured and derived from Mie theory), specific extinction coefficient, and asymmetry factor (which were derived from Mie theory) are also presented. Where available, evolution of the physical and optical properties of the aerosol has been highlighted. Comparisons with long-term ground-based AERONET aerosol retrievals show reasonable agreement. Our observations provide useful data for validating and improving global circulation models (GCMs) that use physically based aerosol representation and for validating satellite retrievals of the physical and optical properties of aerosols. 相似文献
11.
Aerosol retrieval algorithms for the MODerate Resolution Imaging Spectroradiometer (MODIS) have been developed to estimate aerosol and microphysical properties of the atmosphere, which help to address aerosol climatic issues at global scale. However, higher spatial resolution aerosol products for urban areas have not been well-researched mainly due to the difficulty of differentiating aerosols from bright surfaces in urban areas. Here, an aerosol retrieval algorithm using the MODIS 500-m resolution bands is described, to retrieve aerosol properties over Hong Kong and the Pearl River Delta region. The rationale of our technique is to first estimate the aerosol reflectances by decomposing the top-of-atmosphere reflectances from surface reflectances and Rayleigh path reflectances. For the determination of surface reflectances, a Minimum Reflectance Technique (MRT) is used, and MRT images are computed for different seasons. For conversion of aerosol reflectance to aerosol optical thickness (AOT), comprehensive Look Up Tables specific to the local region are constructed, which consider aerosol properties and sun-viewing geometry in the radiative transfer calculations. Four local aerosol types, namely coastal urban, polluted urban, dust, and heavy pollution, were derived using cluster analysis on 3 years of AERONET measurements in Hong Kong. The resulting 500 m AOT images were found to be highly correlated with ground measurements from the AERONET (r2 = 0.767) and Microtops II sunphotometers (r2 = 0.760) in Hong Kong. This study further demonstrates the application of the fine resolution AOT images for monitoring inter-urban and intra-urban aerosol distributions and the influence of trans-boundary flows. These applications include characterization of spatial patterns of AOT within the city, and detection of regional biomass burning sources. 相似文献
12.
通过实验收集大气颗粒物，对南京地区大气气溶胶谱分布进行了描述，对气溶胶分布与相对湿度的相关性进行了探讨。建立了南京地区7—11月气溶胶化学组分的月平均模型，得出气溶胶等效复折射率的预测方法。结果表明：南京地区的大气气溶胶颗粒物，峰值粒径在80~100 nm范围，属于典型的城市型气溶胶。数浓度与相对湿度的相关性与季节和粒径大小有关，在6—9月，相对湿度与细粒子数浓度呈负相关，与粗粒子呈正相关，在10—11月相反，且易受极端天气影响。建立的干气溶胶等效复折射率月平均模型，结合湿度修正模型得到某一日的复折射率，与AERONET站点数据进行了对比，结果较为一致，误差范围在0~0.03。 相似文献
13.
P. C. S. Devara Sumit Kumar G. Pandithurai P. D. Safai S. Dipu 《Meteorology and Atmospheric Physics》2013,120(3-4):189-200
To comprehend the characteristics of heterogeneous aerosols, apart from some thematic multi-institutional, multi-platform and multi-parameter campaigns conducted at several places over the globe, presently two major ground-based networks, involving Cimel (AERONET) and Prede (SKYNET) Sun/sky photometers/radiometers have been in progress. In this paper, we report the results of a study that has been undertaken to compare the performance and data products of Cimel and Prede instruments, which were operated concurrently for a period of about 2 years, at the Indian Institute of Tropical Meteorology, Pune, India. The results show a good agreement in the direct Sun observations (aerosol optical depth). The results are also substantiated by making comparison with surface-level black carbon aerosol mass concentration, apart from comparison of other parameters. With regard to the retrieved products such as aerosol size distribution, Prede shows more or less equal concentration of fine mode and relatively more concentration of coarse mode aerosol as compared to those measured by the Cimel. Moreover, the single scattering albedo values measured by the Prede overestimate those observed by the Cimel. These deviations are found to be primarily due to the nature of aerosol loading (turbidity) in the sensing region which is sensitive to the data retrieval techniques including model assumptions employed in both networks. The results of the present study are found useful for multidimensional mapping of aerosol characteristics by integrating the products from both AERONET and SKYNET monitoring stations and thereby help understanding better the impact of aerosols on climate. 相似文献
14.
Identification of Aerosol Types and Their Optical Properties in the North China Plain Based on Long-Term AERONET Data 
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下载免费PDF全文 SUN Li XIA Xiang-Ao WANG Pu-Cai CHEN Hong-Bin Philippe GOLOUB ZHANG Wen-Xing 《大气和海洋科学快报》2013,(4):216-222
Characterization of aerosols is required to reduce uncertainties in satellite retrievals of global aerosols and for modeling the effects of these aerosols on climate.Aerosols in the North China Plain(NCP) are complex,which provides a good opportunity to study key aerosol optical properties for various aerosol types.A cluster analysis of key optical properties obtained from Aerosol Robotic Network(AERONET) data in Beijing and Xianghe during 2001-11 was performed to identify dominant aerosol types and their associated optical properties.Five dominant aerosol types were identified.The results show that the urban/industrial aerosol of moderate absorption was dominant in the region and that this type varied little with season.Urban/industrial aerosol of weak absorption was the next most common type and mainly occurs in summer,followed by that strong aerosols occurring mainly in winter.All were predominantly fine mode particles.Mineral dust(MD) and polluted dust(PD) occurred mainly in spring,followed by winter,and their absorption decreased with wavelength.In addition,aerosol dynamics and optical parameters such as refractive index and asymmetry factor were examined.Results show that the size of coarse mode particles decreased with AOD indicating the domination of external mixing between aerosols. 相似文献
15.
近年来华东地区大气气溶胶的时空特征 总被引：4，自引：1，他引：3
利用2000年2月—2008年12月的AERONET（AErosol RObotic NETwork）地基观测数据对MODIS/TERRA Collection 005气溶胶光学厚度（aerosol optical thickness;AOT）在华东区域的适用性进行了验证,并利用验证后的MODIS气溶胶产品对华东区域气溶胶光学厚度和尺度分布特征进行了分析。结果表明,（1）通过验证比较,MODIS的AOT在华东区域与AERONET站陆基观测到的AOT具有非常好的一致性,满足美国NASA的设计要求。（2）华东区域的气溶胶光学厚度存在明显的时空分布特征。时间上,在春季和夏季达到最大,而在秋季和冬季最小,表现出明显的季节变化规律。空间上,气溶胶光学厚度受地形影响明显。其高值区主要分布在平原地区,而低值区主要在海拔较高的山区。（3）该区域的气溶胶尺度分布也存在显著的变化特征。在冬、春由于沙尘输送的影响,整个华东区域气溶胶粒子的尺度都比较大,主要以自然生成的沙尘粒子为主。而在夏、秋季由于夏季风和降水的影响,气溶胶粒子的尺度都比较小,以工业排放的人为气溶胶粒子为主。 相似文献
16.
Considered is a possibility of specifying the forecast of volcanic aerosol distribution in the atmosphere using the data of ground-based actinometric measurements. To simulate the aerosol distribution, the FlexPart software (Norwegian Institute for Air Research) was used. Using the FlexGraph software (Planeta Research Center for Space Hydrometeorology), the visualization and interactive analysis were carried out of aerosol concentration fields at different time moments. The prognostic concentration of volcanic ash from Grímsvötn volcano (May 2011) is bound to the results of measurements of aerosol optical depth in Hamburg at one of the points of AERONET global network. The comparison of the corrected aerosol concentration with the measurements at other AERONET points demonstrated the competence of the proposed approach. To specify the aerosol cloud distribution forecast on the territory of Russia, the Roshydromet actinometric network data can be used. 相似文献
17.
Comparison of Aerosol Single Scattering Albedo Derived from the Ozone Monitoring Instrument with Aerosol Robotic Network Observations 下载免费PDF全文
下载免费PDF全文 The single-scattering albedo (SSA), which quantifies radiative absorption capability, is an important optical property of aerosols. Ground-based methods have been extensively exploited to determine aerosol SSA but there were no satellite-based SSA measurements available until the advent of advanced remote sensing techniques, such as the Ozone Monitoring Instrument (OMI). Although the overall accuracy of OMI SSA is estimated to approach 0.1, its regional availability is unclear. Four-year SSA daily measurements from three Aerosol Robotic Network (AERONET) sites in China (Xianghe, Taihu, and Hong Kong) are chosen to determine the accuracy of OMI SSA in specific locations. The results show that on a global scale, the OMI SSA is systematically higher (with a mean relative bias of 3.5% and a RMS difference of ~0.06) and has poor correlation with the AERONET observations. In the Xianghe, Taihu, and Hong Kong sites, the correlation coefficients are 0.16, 0.47, and 0.44, respectively, suggesting that the distinct qualities of OMI SSA depend on geographic locations and/or dominant aerosol environments. The two types of SSA data yield the best agreement in Taihu and the worst in Hong Kong; the differing behavior is likely caused by varying levels of cloud contamination. The good consistency of the aerosol variation between the two SSA datasets on a seasonal scale is promising. These findings suggest that the current-version OMI SSA product can be applied to qualitatively characterize climatological variations of aerosol properties despite its limited accuracy as an instantaneous measurement. 相似文献
18.
The spatial–temporal properties of aerosol types over China are studied using the radiance measurements and inversions data at four Aerosol Robotic Network (AERONET) stations in China. Based on a cluster analysis, five aerosol classes were identified including a coarse-sized dominated aerosol type (presumably dust) and four fine-sized dominated aerosol types ranging from non-absorbing to highly absorbing fine aerosols. The optical properties and seasonal variations of these aerosol types are investigated. The results of analysis show that: (1) the highly absorbing aerosols usually occur in winter, (2) non-absorbing aerosols are frequently observed in summer; (3) coarse-sized dominated aerosols are frequently occurred in spring. 相似文献
19.
The aerosol optical properties and direct radiative forcing over the Mu Us desert of northern China,
acquired through a CE318 sunphotometer of the ground-based Aerosol Robotic Network (AERONET), are analyzed. The
seasonal variations in the aerosol optical properties are examined. The effect of meteorological elements
(pressure, temperature, water vapor pressure, relative humidity and wind speed) on the aerosol optical properties
is also studied. Then, the sources and optical properties under two different cases, a dust event and a pollution
event, are compared. The results show that the high aerosol optical depth (AOD) found in Yulin was mostly
attributed to the occurrence of dust events in spring from the Mu Us desert and deserts of West China and
Mongolia, as well as the impacts of anthropogenic pollutant particles from the middle part of China in the
other seasons. The seasonal variation and the probability distribution of the radiative forcing and the
radiative forcing efficiency at the surface and the top of the atmosphere are analyzed and regressed using
the linear and Gaussian regression methods. 相似文献
20.
用MODIS反演北京城市地区地表反照率精度以及算法改进 总被引：3，自引：2，他引：1
MODIS(MODerate-resolution Imaging Spectroradiometer)地表反照率的精度在乡村地区已经得到了检验,但是至今没有在城市地区的有关研究。地表反照率的精度在很大程度上取决于大气订正的精度,作者利用2002年以来的北京AERONET(国际气溶胶检测网络)站点Cimel气溶胶观测资料对反射率进行大气订正,通过对比来评价MODIS地表反照率算法中大气订正的精度。结果发现,MODIS大气订正在蓝光波段具有明显的过度订正现象,MODIS大气订正后地表反射率平均偏低0.03。MODIS地表反照率在冬季有约75%的缺测,这是因为冬季严重的空气污染使得MODIS云检测得到晴空观测较少。MODIS使用三参数双向反射率函数（BRDF）要求16天以内至少有3次以上的晴空观测（MODIS算法中要求7次）。通过分析MODIS反演得到的三参数,发现虽然它们的绝对值具有明显的季节变化,但是它们的比值是十分稳定的,这样使BRDF函数降低到只需要一个参数,有效降低了对晴空观测次数的要求,这一思想可以应用到热带等晴空日数较少的地区。 相似文献