Knowledge of the statistical characteristics of inversions and their effects on aerosols under different large-scale synoptic circulations is important for studying and modeling the diffusion of pollutants in the boun...Knowledge of the statistical characteristics of inversions and their effects on aerosols under different large-scale synoptic circulations is important for studying and modeling the diffusion of pollutants in the boundary layer. Based on results gen- erated using the self-organizing map （SOM） weather classification method, this study compares the statistical characteristics of surface-based inversions （SBIs） and elevated inversions （EIs）, and quantitatively evaluates the effect of SBIs on aerosol condensation nuclei （CN） concentrations and the relationship between temperature gradients and aerosols for six prevailing synoptic patterns over the the Southern Great Plains （SGP） site during 2001-10. Large-scale synoptic patterns strongly influ- ence the statistical characteristics of inversions and the accumulation of aerosols in the low-level atmosphere. The activity, frequency, intensity, and vertical distribution of inversions are significantly different among these synoptic patterns. The verti- cal distribution of inversions varies diurnally and is significantly different among the different synoptic patterns. Anticyclonic patterns affect the accumulation of aerosols near the ground more strongly than cyclonic patterns. Mean aerosol CN con- centrations increase during SBIs compared to no inversion cases by 16.1%, 22.6%, 24.5%, 58.7%, 29.8% and 23.7% for the six synoptic patterns. This study confirms that there is a positive correlation between temperature gradients and aerosol CN concentrations near the ground at night under similar large-scale synoptic patterns. The relationship is different for different synoptic patterns and can be described by linear functions. These findings suggest that large-scale synoptic patterns change the static stability of the atmosphere and inversions in the lower atmosphere, thereby influencing the diffusion of aerosols near the ground.展开更多
Based on a vector radiative transfer model of the atmosphere–ocean system,the influence of oceanic components on radiation processes,including polarization effects,was investigated in the wavelength region ranging fr...Based on a vector radiative transfer model of the atmosphere–ocean system,the influence of oceanic components on radiation processes,including polarization effects,was investigated in the wavelength region ranging from 0.380 to 0.865 μm.The components considered were phytoplankton,inorganic suspended material（sediment）,and colored,dissolved organic matter.Due to their important roles in oceanic radiation processes,the sensitivity of the bidirectional reflectance to the rough ocean surface,represented by the wind velocity 10 m above the ocean surface,and aerosol,were taken into account.The results demonstrated that both radiance and polarized radiance just below the ocean surface were sensitive to the change of the concentrations of the considered components,while the dependence of polarized radiance on the observation geometry was more sensitive than radiance.Significant differences in the specular plane existed between the impacts of the phytoplankton and sediment on the degree of polarization just above the ocean surface at 670 nm.At the top of the atmosphere（TOA）,polarization was relatively insensitive to changing concentrations of ocean particles at longer wavelengths.Furthermore,the radiance at the TOA in the solar plane was more sensitive to the aerosol optical thickness than wind velocity.In contrast,wind velocity strongly influenced the radiance at the TOA in the sun glint region,while the polarization degree showed less dependence in that region.Finally,a nonlinear optimal inversion method was proposed to simultaneously retrieve the aerosol and wind velocity using radiance measurement.展开更多
The effect of the air quality ensuring measures for the Beijing 2008 Olympic Games in reducing air pollution during the game period is assessed using the tropospheric NO2 column density retrieved from Ozone Monitoring...The effect of the air quality ensuring measures for the Beijing 2008 Olympic Games in reducing air pollution during the game period is assessed using the tropospheric NO2 column density retrieved from Ozone Monitoring Instrument onboard AURA satel- lite. The basic method of the assessment is the comparison of the NO2 column densities during the game period with that during the corresponding period of 2005?2007 for the Beijing area, and the comparison among Beijing and neighbouring cities Tianjin and Tangshan, which are of similar situation in air pollution of NO2 in recent years. The images of tropospheric NO2 column den- sities over Northern China during the Beijing 2008 Olympic Games show the remarkable effect of the air quality ensuring meas- ures in reducing NO2 pollution: the tropospheric NO2 column density in Beijing is much lower than that in Tianjin and Tangshan, while there were very similar values in the three large cities during the same period of the last three years. About 40% reduction in tropospheric NO2 column density over the Beijing area is obtained from the assessment during July to August, 2008, a key period of air quality ensuring measures for the Beijing 2008 Olympic Games.展开更多
The Chinese Sun Hazemeter Network (CSHNET) provides the necessary ground-based observation to validate and assess the applicability of MODIS aerosol optical depth (AOD) products over different ecological and geographi...The Chinese Sun Hazemeter Network (CSHNET) provides the necessary ground-based observation to validate and assess the applicability of MODIS aerosol optical depth (AOD) products over different ecological and geographic regions in China for the first time. The validation results show that the comprehensive utilization ratio and applicability of MODIS products varied very much over different regions and seasons from August 2004 to July 2005. On the Tibetan Plateau, the comprehensive utili- zation ratio of MODIS data was low: MODIS products only accounted for 16% of the ground-based observation; on average, 31% to 45% of MODIS products fell within the retrieval errors issued by NASA. A similar result was found in northern desert areas with the ratio of MODIS to observation ranging from 15% to 55%, with 7% to 39% of MODIS products within errors. In the remote northeast corner of China, low ratios of MODIS to observation were also found ranging from 14% to 46%, with 49% to 69% of MODIS within errors. The forested sites exhibited moderate ratios of MODIS to observation ranging from 46% to 65%, with 30% to 59% of MODIS within errors. This was similar to numbers observed at sites along eastern seashore of China and inland urban sites with the ratio of MODIS to observation between 63% to 75%, with 25% to 67% of MODIS within errors for sites along eastern seashore of China and 43% to 78%, with 35% to 75% of MODIS within errors for inland urban sites. The ratio of MODIS to observation over agricultural areas ranged from 61% to 89%; 59%-88% of MODIS fell within the retrieval errors. At homogeneous and well vegetated areas, the comprehensive utilization ratio of MODIS products was over 80% and above 70% of MODIS products fell within the retrieval errors in growing season.展开更多
Based on the optimal estimation method, a satellite XCO2 retrieval algorithm was constructed by combining LBLRTM with VLIDORT. One-year GOSAT/TANSO observations over four TCCON stations were tested by our algorithm, a...Based on the optimal estimation method, a satellite XCO2 retrieval algorithm was constructed by combining LBLRTM with VLIDORT. One-year GOSAT/TANSO observations over four TCCON stations were tested by our algorithm, and retrieval results were compared with GOSAT L2 B products and ground-based FTS measurements. Meanwhile, the influence of CO2 line mixing effect on retrieval was estimated, and the research showed that neglecting CO2 line mixing effect could result in approximately 0.25% XCO2 underestimation. The accuracy of XCO2 retrievals was similar to GOSAT L2 B products at cloud-free footprints with aerosol optical depth less than 0.3, and 1% accuracy of XCO2 retrievals can be reached based on the validation result with TCCON measurements.展开更多
基金sponsored by the U.S. Department of Energy (DOE)supported by the Ministry of Science and Technology of China (Grant Nos. 2010CB950804 and 2013CB955801)+1 种基金the "Strategic Priority Research Program" of the Chinese Academy of Sciences (Grant No. XDA05100300)the National Natural Science Foundation of China (Grant No. 41305011)
文摘Knowledge of the statistical characteristics of inversions and their effects on aerosols under different large-scale synoptic circulations is important for studying and modeling the diffusion of pollutants in the boundary layer. Based on results gen- erated using the self-organizing map （SOM） weather classification method, this study compares the statistical characteristics of surface-based inversions （SBIs） and elevated inversions （EIs）, and quantitatively evaluates the effect of SBIs on aerosol condensation nuclei （CN） concentrations and the relationship between temperature gradients and aerosols for six prevailing synoptic patterns over the the Southern Great Plains （SGP） site during 2001-10. Large-scale synoptic patterns strongly influ- ence the statistical characteristics of inversions and the accumulation of aerosols in the low-level atmosphere. The activity, frequency, intensity, and vertical distribution of inversions are significantly different among these synoptic patterns. The verti- cal distribution of inversions varies diurnally and is significantly different among the different synoptic patterns. Anticyclonic patterns affect the accumulation of aerosols near the ground more strongly than cyclonic patterns. Mean aerosol CN con- centrations increase during SBIs compared to no inversion cases by 16.1%, 22.6%, 24.5%, 58.7%, 29.8% and 23.7% for the six synoptic patterns. This study confirms that there is a positive correlation between temperature gradients and aerosol CN concentrations near the ground at night under similar large-scale synoptic patterns. The relationship is different for different synoptic patterns and can be described by linear functions. These findings suggest that large-scale synoptic patterns change the static stability of the atmosphere and inversions in the lower atmosphere, thereby influencing the diffusion of aerosols near the ground.
基金funded by the National Key Research and Development Program of China [grant numbers2017YFB0504000 and 2017YFC1501701]the National Natural Science Foundation of China [grant number 41575034]
基金supported by the "Strategic Priority Research Program" of the Chinese Academy of Sciences(Grant No.XDA05100300)the National Basic Research Program of China(Grant No.2013CB955801)+2 种基金the National Natural Science Foundation of China(Grant Nos.41175030 and 41475136)the National Basic Research Program of China(Grant No.2014CB953703)funds from MOEJ/GOSAT&GOSAT2,JST/CREST/EMS/TEEDDA,JAXA/ Earth CARE&GCOM-C,MEXT/RECCA/SALSA,MEXT/Kakenhi/ Innovative Areas 2409,and MOEJ/ERTDF/S-12
文摘Based on a vector radiative transfer model of the atmosphere–ocean system,the influence of oceanic components on radiation processes,including polarization effects,was investigated in the wavelength region ranging from 0.380 to 0.865 μm.The components considered were phytoplankton,inorganic suspended material（sediment）,and colored,dissolved organic matter.Due to their important roles in oceanic radiation processes,the sensitivity of the bidirectional reflectance to the rough ocean surface,represented by the wind velocity 10 m above the ocean surface,and aerosol,were taken into account.The results demonstrated that both radiance and polarized radiance just below the ocean surface were sensitive to the change of the concentrations of the considered components,while the dependence of polarized radiance on the observation geometry was more sensitive than radiance.Significant differences in the specular plane existed between the impacts of the phytoplankton and sediment on the degree of polarization just above the ocean surface at 670 nm.At the top of the atmosphere（TOA）,polarization was relatively insensitive to changing concentrations of ocean particles at longer wavelengths.Furthermore,the radiance at the TOA in the solar plane was more sensitive to the aerosol optical thickness than wind velocity.In contrast,wind velocity strongly influenced the radiance at the TOA in the sun glint region,while the polarization degree showed less dependence in that region.Finally,a nonlinear optimal inversion method was proposed to simultaneously retrieve the aerosol and wind velocity using radiance measurement.
基金supported by the funds of Beijing Municipal Science and Technol-ogy Commission (Grant No. Z005190042791)National Natural Science Foundation of China (Grant No. 40875084)+1 种基金National Basic Research Pro-gram of China (Grant No. 2006CB403702)EU PF6 AMFIC Project
文摘The effect of the air quality ensuring measures for the Beijing 2008 Olympic Games in reducing air pollution during the game period is assessed using the tropospheric NO2 column density retrieved from Ozone Monitoring Instrument onboard AURA satel- lite. The basic method of the assessment is the comparison of the NO2 column densities during the game period with that during the corresponding period of 2005?2007 for the Beijing area, and the comparison among Beijing and neighbouring cities Tianjin and Tangshan, which are of similar situation in air pollution of NO2 in recent years. The images of tropospheric NO2 column den- sities over Northern China during the Beijing 2008 Olympic Games show the remarkable effect of the air quality ensuring meas- ures in reducing NO2 pollution: the tropospheric NO2 column density in Beijing is much lower than that in Tianjin and Tangshan, while there were very similar values in the three large cities during the same period of the last three years. About 40% reduction in tropospheric NO2 column density over the Beijing area is obtained from the assessment during July to August, 2008, a key period of air quality ensuring measures for the Beijing 2008 Olympic Games.
基金Supported by the National Natural Science Foundation of China (Grants Nos. 40675073, 40525016 and 40520120071)the National Basic Research Program (973) of China (Grant No. 2007CB407303)
文摘The Chinese Sun Hazemeter Network (CSHNET) provides the necessary ground-based observation to validate and assess the applicability of MODIS aerosol optical depth (AOD) products over different ecological and geographic regions in China for the first time. The validation results show that the comprehensive utilization ratio and applicability of MODIS products varied very much over different regions and seasons from August 2004 to July 2005. On the Tibetan Plateau, the comprehensive utili- zation ratio of MODIS data was low: MODIS products only accounted for 16% of the ground-based observation; on average, 31% to 45% of MODIS products fell within the retrieval errors issued by NASA. A similar result was found in northern desert areas with the ratio of MODIS to observation ranging from 15% to 55%, with 7% to 39% of MODIS products within errors. In the remote northeast corner of China, low ratios of MODIS to observation were also found ranging from 14% to 46%, with 49% to 69% of MODIS within errors. The forested sites exhibited moderate ratios of MODIS to observation ranging from 46% to 65%, with 30% to 59% of MODIS within errors. This was similar to numbers observed at sites along eastern seashore of China and inland urban sites with the ratio of MODIS to observation between 63% to 75%, with 25% to 67% of MODIS within errors for sites along eastern seashore of China and 43% to 78%, with 35% to 75% of MODIS within errors for inland urban sites. The ratio of MODIS to observation over agricultural areas ranged from 61% to 89%; 59%-88% of MODIS fell within the retrieval errors. At homogeneous and well vegetated areas, the comprehensive utilization ratio of MODIS products was over 80% and above 70% of MODIS products fell within the retrieval errors in growing season.
基金supported by the National High Technology Research and Development Program of China(Grant No.2011AA12A104-3)the Strategic Priority Research Program(Grant No.XDA05100300)+4 种基金the European Commission’s Seventh Framework Program"PANDA"(Grant No.FP7-SPACE-2013-1)the Public Industry-specific Fund for Meteorology(Grant No.GYHY201106045)the 4th and 5th GOSAT/TANSO Joint Research Project,National Basic Research Program of China(Grant No.2013CB955801)National Natural Science Foundation of China(Grant No.41175030)China Earth Observation Project(Grant No.E310/1112)
文摘Based on the optimal estimation method, a satellite XCO2 retrieval algorithm was constructed by combining LBLRTM with VLIDORT. One-year GOSAT/TANSO observations over four TCCON stations were tested by our algorithm, and retrieval results were compared with GOSAT L2 B products and ground-based FTS measurements. Meanwhile, the influence of CO2 line mixing effect on retrieval was estimated, and the research showed that neglecting CO2 line mixing effect could result in approximately 0.25% XCO2 underestimation. The accuracy of XCO2 retrievals was similar to GOSAT L2 B products at cloud-free footprints with aerosol optical depth less than 0.3, and 1% accuracy of XCO2 retrievals can be reached based on the validation result with TCCON measurements.
