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Evolution of Meteorological Conditions during a Heavy Air Pollution Event under the Influence of Shallow Foehn in Urumqi, China
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作者 Xia LI Keming ZHAO +5 位作者 Shiyuan ZHONG Xiaojing YU Zhimin FENG Yuting ZHONG Ayitken MAULEN Shuting LI 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2023年第1期29-43,共15页
The air pollution in Urumqi which is located on the northern slope of the Tianshan Mountains in northwestern China,is very serious in winter.Of particular importance is the influence of terrain-induced shallow foehn,k... The air pollution in Urumqi which is located on the northern slope of the Tianshan Mountains in northwestern China,is very serious in winter.Of particular importance is the influence of terrain-induced shallow foehn,known locally as elevated southeasterly gale(ESEG).It usually modulates atmospheric boundary layer structure and wind field patterns and produces favorable meteorological conditions conducive to hazardous air pollution.During 2013-17,Urumqi had an average of 50 d yr-1 of heavy pollution(daily average PM2.5 concentration>150μg m-3),of which 41 days were in winter.The majority(71.4%)of heavy pollution processes were associated with the shallow foehn.Based on microwave radiometer,wind profiler,and surface observations,the surface meteorological fields and boundary layer evolution during the worst pollution episode in Urumqi during 16-23 February 2013 are investigated.The results illustrate the significant role of shallow foehn in the building,strengthening,and collapsing of temperature inversions.There were four wind field patterns corresponding to four different phases during the whole pollution event.The most serious pollution phase featured shallow foehn activity in the south of Urumqi city and the appearance of an intense inversion layer below 600 m.Intense convergence caused by foehn and mountain-valley winds was sustained during most of the phase,resulting in pollutants sinking downward to the lower boundary layer and accumulating around urban area.The key indicators of such events identified in this study are highly correlated to particulate matter concentrations and could be used to predict heavy pollution episodes in the feature. 展开更多
关键词 FOEHN elevated southeasterly gale(ESEG) heavy air pollution boundary layer structure wind field pattern complex terrain
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A study of the validation of atmospheric CO_2 from satellite hyper spectral remote sensing 被引量:1
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作者 ZHANG Miao ZHANG Xing-Ying +1 位作者 LIU Rui-Xia HU Lie-Qun 《Advances in Climate Change Research》 SCIE 2014年第3期131-135,共5页
Three total column dry-air mole fractions of CO_2(XCO_2) products from satellite retrievals, namely SCIAMACHY, NIES-GOSAT, and ACOS-GOSAT, in the Northern Hemisphere were validated by ground data from the Total Carbon... Three total column dry-air mole fractions of CO_2(XCO_2) products from satellite retrievals, namely SCIAMACHY, NIES-GOSAT, and ACOS-GOSAT, in the Northern Hemisphere were validated by ground data from the Total Carbon Column Observing Network(TCCON). The results showed that the satellite data have the same seasonal fluctuations as in the TCCON data, with maximum in April or May and minimum in August or September. The three products all underestimate the XCO2. The ACOS-GOSAT and the NIES-GOSAT products are roughly equivalent, and their mean standard deviations are 2.26 × 10^(-6)and 2.27 × 10^(-6)respectively. The accuracy of the SCIMACHY product is slightly lower, with a mean standard deviation of 2.91 × 10^(-6). 展开更多
关键词 CO2 SATELLITE REMOTE SENSING VALIDATION
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Site-testing at the Muztagh-ata Site V.Nighttime Cloud Amount during the Last Five Years
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作者 Jing Xu Guo-jie Feng +12 位作者 Guang-xin Pu Le-tian Wang Zi-Huang Cao Li-Qing Ren Xuan Zhang Shu-guo Ma Chun-hai Bai Ali Esamdin Jian Li Yuan Tian Zheng Wang Yong-heng Zhao Jian-rong Shi 《Research in Astronomy and Astrophysics》 SCIE CAS CSCD 2023年第4期164-171,共8页
The clarity of nights is the major factor that should be carefully considered for optical/infrared astronomical observatories in site-testing campaigns.Cloud coverage is directly related to the amount of time availabl... The clarity of nights is the major factor that should be carefully considered for optical/infrared astronomical observatories in site-testing campaigns.Cloud coverage is directly related to the amount of time available for scientific observations at observatories.In this article,we report on the results of detailed night-time cloud statistics and continuous observing time derived from ground-based all-sky cameras(ASCs)at the Muztagh-ata site from 2017to 2021.Results obtained from acquisition data show that the proportion of the annual observing time at the Muztagh-ata site is 65%,and the best period with the least cloud coverage and longer continuous observing time is from September to February.We made a comparison of the monthly mean observing nights obtained from our ASC and CLARA data set,and results show that the discrepancy between them may depend on the cloud top heights.On average,this site can provide 175 clear nights and 169 nights with at least 4 hr of continuous observing time per year. 展开更多
关键词 site testing-atmospheric effects-methods statistical
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XCO_2 satellite retrieval experiments in short-wave infrared spectrum and ground-based validation 被引量:4
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作者 ZHOU MinQiang ZHANG XingYing +3 位作者 WANG PuCai WANG ShuPeng GUO LiLi HU LieQun 《Science China Earth Sciences》 SCIE EI CAS CSCD 2015年第7期1191-1197,共7页
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
关键词 carbon dioxide retrieval experiments satellite high-spectral remote sensing ground-based validation
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Study on Snow Line in the Tianshan Mountains Based on MODIS Image
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作者 Xuefei SONG Liancheng ZHANG Liequn HU 《Asian Agricultural Research》 2015年第8期60-63,共4页
Using MOD10A1,temperature and precipitation of 21 meteorological observatories and HJ-1 / CCD data from July to September during 2002- 2013,this paper takes the Tianshan Mountains as the study area to analyze the spac... Using MOD10A1,temperature and precipitation of 21 meteorological observatories and HJ-1 / CCD data from July to September during 2002- 2013,this paper takes the Tianshan Mountains as the study area to analyze the space distribution characteristics of snow line and its influencing factors. The results show that the snowline distribution of southern and northern slopes of the Tianshan Mountains is that it is high in the south and east but low in north and west; the snowline of southern slope is sparse and there is a small spatial gradient change; the snow line is dense in the middle of northern slope,and the spatial gradient change is not large. Through the analysis of the whole study area,it is found that the correlation coefficient between snow line altitude and temperature is 0. 159,and the partial correlation coefficient between them is- 0. 212; the correlation coefficient between snow line altitude and precipitation is- 0. 668,and the partial correlation coefficient between them is- 0. 676. Precipitation is the dominant factor that affects the distribution of snow line of southern and northern slopes of the Tianshan Mountains. 展开更多
关键词 SOUTHERN and northern SLOPES of the TIANSHAN MOUNT
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Example of research on relation between satellite thermal infrared anomaly and strong earthquake
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作者 叶民权 吴其勇 杨忠东 《Chinese Science Bulletin》 SCIE EI CAS 1995年第7期576-580,共5页
People pay more and more attention to the coupling relation between ground and air.In seismogenic process, thermal anomaly and temperature redistribution are generated not onlyin source region but also in its surround... People pay more and more attention to the coupling relation between ground and air.In seismogenic process, thermal anomaly and temperature redistribution are generated not onlyin source region but also in its surrounding areas. This causes various thermal effects 展开更多
关键词 thermal infrared ANOMALY prediction STRONG earthquake.
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Spatio-temporal variations and influencing factors of energy-related carbon emissions for Xinjiang cities in China based on time-series nighttime light data 被引量:5
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作者 ZHANG Li LEI Jun +3 位作者 WANG Changjian WANG Fei GENG Zhifei ZHOU Xiaoli 《Journal of Geographical Sciences》 SCIE CSCD 2022年第10期1886-1910,共25页
This essay combines the Defense Meteorological Satellite Program Operational Linescan System(DMSP-OLS)nighttime light data and the Visible Infrared Imaging Radiometer Suite(VIIRS)nighttime light data into a“synthetic... This essay combines the Defense Meteorological Satellite Program Operational Linescan System(DMSP-OLS)nighttime light data and the Visible Infrared Imaging Radiometer Suite(VIIRS)nighttime light data into a“synthetic DMSP”dataset,from 1992 to 2020,to retrieve the spatio-temporal variations in energy-related carbon emissions in Xinjiang,China.Then,this paper analyzes several influencing factors for spatial differentiation of carbon emissions in Xinjiang with the application of geographical detector technique.Results reveal that(1)total carbon emissions continued to grow,while the growth rate slowed down in the past five years.(2)Large regional differences exist in total carbon emissions across various regions.Total carbon emissions of these regions in descending order are the northern slope of the Tianshan(Mountains)>the southern slope of the Tianshan>the three prefectures in southern Xinjiang>the northern part of Xinjiang.(3)Economic growth,population size,and energy consumption intensity are the most important factors of spatial differentiation of carbon emissions.The interaction between economic growth and population size as well as between economic growth and energy consumption intensity also enhances the explanatory power of carbon emissions’spatial differentiation.This paper aims to help formulate differentiated carbon reduction targets and strategies for cities in different economic development stages and those with different carbon intensities so as to achieve the carbon peak goals in different steps. 展开更多
关键词 carbon emissions nighttime light data spatio-temporal variations influencing factors XINJIANG
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