排序方式： 共有37条查询结果，搜索用时 31 毫秒
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开发AVHRR可见光通道反演陆地气溶胶光学厚度 (AOD) 的算法对于研究长时间序列AOD的变化有重要意义。AVHRR由于缺少2.1 μm通道而不能采用MODIS的暗背景算法,该文利用背景合成算法进行陆地AOD反演。背景合成算法是指假设一段时间内地表反射率变化不大且会出现相对清洁大气, 采用最小值合成即可得到地表反射率,再通过辐射传输模式6S制作的查算表查算得到AOD的反演结果。将此算法应用到2009年AVHRR中国部分陆地区域 (15°~45°N,75°~135°E) 得到AOD的时空分布,将反演结果与同期Aqua/MODIS的MOD04 AOD产品进行对比分析表明,华北和华东地区的反演效果较好,西北地区结果较差。以长江三角洲地区为例可知,AVHRR AOD产品与MODIS AOD产品以及AERONET观测的AOD相比相关系数基本在0.6以上,从时间变化规律来看,AVHRR AOD和MODIS AOD产品年变化趋势具有很好的一致性。该文为建立长时间序列AVHRR AOD数据集提供了一个较为可行的方法。 相似文献
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Comparison of Aerosol Single Scattering Albedo Derived from the Ozone Monitoring Instrument with Aerosol Robotic Network Observations 
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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
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Ricardo M. Llamas Roberto Bonifaz Mauro Valdés David Riveros-Rosas Amando LeyvaContreras 《Geofísica Internacional》2013,52(4):321-341
The purpose of this paper was to study aerosol particles in the Northwestern region of Mexico (NWM) through Aerosol Optical Thickness (AOT) parameter in the atmosphere. This parameter represents one of the extinction coefficients of solar radiation and the rate of suspended particles in the atmosphere. For determination of AOT, we considered the use of remote sensors outside of the atmosphere. In particular, Moderate Resolution Imaging Spectroradiometer (MODIS) which can measure the atmospheric AOT thickness. Data from the MODIS sensor must be validated before they are considered reliable. For this task, we required surface measurements to obtain a correlation with the data acquired with the remote radiometer. The paper describes the validation process performed for data obtained with MODIS through measurements provided by an AErosol RObotic NETwork (AERONET) photometer located in the city of Hermosillo, Sonora, NWM. Additionally, we carried out a temporal analysis based on the behavior of the AOT graphics and spatial analysis supported in maps with sufficient information. 相似文献
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黄土高原半干旱地区气溶胶光学厚度变化特征的初步分析 总被引：3，自引：2，他引：1
利用"兰州大学半干旱气候与环境观测站"2006年8月至2007年4月的CE-318全自动跟踪太阳光度计观测资料,分析了黄土高原半干旱地区气溶胶光学厚度(AOD)的变化特征。结果表明,黄土高原半干旱地区气溶胶光学厚度谱基本满足Angstrom关系;在可见光和近红外波段,随着波长的增大,气溶胶光学厚度是减小的;黄土高原半干旱地区AOD日变化类型主要有单峰型、稳定型、上升型3种。逐日变化特征显示,降水对气溶胶粒子具有明显的湿清除作用,霾的出现导致AOD明显增大;AOD日均值主要集中在0.1~0.4之间,日极大值在08~11时(北京时,下同)出现的频率最多,日极小值在12~13时、14~17时出现的频率最多。气象条件对AOD有明显的影响,在南风情况下AOD大,东风情况下AOD小,霾与晴天相比,AOD明显增大;对同一波段,风向差别引起的AOD的差异较晴天与霾相比引起的AOD的差异要小。 相似文献
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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, a new aerosol retrieval algorithm using the MODIS 500 m resolution image... 相似文献
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王家成 《地球信息科学学报》2014,16(5):790-796
目前,偏振遥感已被用于气溶胶卫星和地基遥感中,其仅对小粒子敏感。本研究以2007-2008年间的POLDER(Polarization and Directionality of the Earth’s Reflectances)和AERONET(Aerosol Robotic Network)合肥站的气溶胶数据为研究对象,探讨了偏振遥感对气溶胶粒子尺度的敏感性。利用AERONET合肥站的尺度分布数据和折射指数数据,计算了不同尺度范围内气溶胶粒子的光学厚度,并与对应的POLDER反演结果作拟合,通过寻找最佳拟合对应的尺度范围确定偏振遥感敏感的粒子尺度。结果表明,偏振遥感并非对所有尺度的小模式气溶胶粒子都敏感,在865 nm波段,其敏感的气溶胶粒子上限半径约为0.3 μm左右。这一结果对指导气溶胶偏振遥感,以及理解和应用偏振遥感气溶胶产品等具有重要意义。 相似文献
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Dipesh Rupakheti Maheswar Rupakheti Xiufeng Yin Julian Hofer Mukesh Rai Yuling Hu Sabur F.Abdullaev Shichang Kang 《地学前缘(英文版)》2021,12(6):299-312
The location of Central Asia,almost at the center of the global dust belt region,makes it susceptible for dust events.The studies on atmospheric impact of dust over the region are very limited despite the large area occupied by the region and its proximity to the mountain regions(Tianshan,Hindu Kush-Karakoram-Himalayas,and Tibetan Plateau).In this study,we analyse and explain the modification in aerosols'phys-ical,optical and radiative properties during various levels of aerosol loading observed over Central Asia utilizing the data collected during 2010-2018 at the AERONET station in Dushanbe,Tajikistan.Aerosol epi-sodes were classified as strong anthropogenic,strong dust and extreme dust.The mean aerosol optical depth(AOD)during these three types of events was observed a factor of～3,3.5 and 6.6,respectively,higher than the mean AOD for the period 2010-2018.The corresponding mean fine-mode fraction was 0.94,0.20 and 0.16,respectively,clearly indicating the dominance of fine-mode anthropogenic aerosol during the first type of events,whereas coarse-mode dust aerosol dominated during the other two types of events.This was corroborated by the relationships among various aerosol parameters(AOD vs.AE,and EAE vs.AAE,SSA and RRI).The mean aerosol radiative forcing(ARF)at the top of the atmosphere(ARFTOA),the bottom of the atmosphere(ARFBOA),and in the atmosphere(ARFATM)were-35±7,-73±16,and 38±17 Wm-2 during strong anthropogenic events,-48±12,-85±24,and 37±15 Wm-2 during strong dust event,and-68±19,-117±38,and 49±21 Wm-2 during extreme dust events.Increase in aerosol loading enhanced the aerosol-induced atmospheric heating rate to 0.5-1.6 K day-1(strong anthropogenic events),0.4-1.9 K day-1(strong dust events)and 0.8-2.7 K day 1(extreme dust events).The source regions of air masses to Dushanbe during the onset of such events are also identified.Our study con-tributes to the understanding of dust and anthropogenic aerosols,in particular the extreme events and their disproportionally high radiative impacts over Central Asia. 相似文献
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利用静止卫星MTSAT反演大气气溶胶光学厚度 总被引：10，自引：1，他引：9
卫星遥感是获取气溶胶光学特性的重要手段,利用静止卫星可见光通道资料反演气溶胶光学厚度(AOD)的算法使用日本静止气象卫星MTSAT可见光通道资料反演了2008年5月中国地区陆地上的气溶胶光学厚度,将得到的结果分别与AERONET站点的地面观测值进行比较,得到了较好的线性相关关系,再将其与相应的MODIS气溶胶光学厚度产品进行比较,也得到了较为一致的分布,表明MTSAT反演的气溶胶光学厚度产品可以反映大气气溶胶光学厚度的日变化信息。最后对这种反演算法的误差来源进行了分析。 相似文献