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| 1 | Changes in visibility with PM_(2.5) composition and relative humidity at a background site in the Pearl River Delta region显示文摘In fall–winter, 2007–2013, visibility and light scattering coefficients(b sp) were measured along with PM_(2.5)mass concentrations and chemical compositions at a background site in the Pearl River Delta(PRD) region. The daily average visibility increased significantly(p < 0.01) at a rate of 1.1 km/year, yet its median stabilized at ~13 km. No haze days occurred when the 24-hr mean PM_(2.5)mass concentration was below 75 μg/m^3. By multiple linear regression on the chemical budget of particle scattering coefficient(b sp), we obtained site-specific mass scattering efficiency(MSE) values of 6.5 ± 0.2, 2.6 ± 0.3, 2.4 ± 0.7 and 7.3 ± 1.2 m2/g,respectively, for organic matter(OM), ammonium sulfate(AS), ammonium nitrate(AN) and sea salt(SS). The reconstructed light extinction coefficient(b ext) based on the Interagency Monitoring of Protected Visual Environments(IMPROVE) algorithm with our site-specific MSE revealed that OM, AS, AN, SS and light-absorbing carbon(LAC) on average contributed 45.9% ± 1.6%,25.6% ± 1.2%, 12.0% ± 0.7%, 11.2% ± 0.9% and 5.4% ± 0.3% to light extinction, respectively.Averaged b ext displayed a significant reduction rate of 14.1/Mm·year(p < 0.05); this rate would be 82% higher if it were not counteracted by increasing relative humidity(RH) and hygroscopic growth factor(f(RH)) at rates of 2.5% and 0.16/year-1(p < 0.01), respectively, during the fall–winter, 2007–2013. This growth of RH and f(RH) partly offsets the positive effects of lowered AS in improving visibility, and aggravated the negative effects of increasing AN to impair visibility. | Xiaoxin Fu Xinming Wang Qihou Hu Guanghui Li Xiang Ding Yanli Zhang Quanfu He Tengyu Liu Zhou Zhang Qingqing Yu Ruqing Shen Xinhui Bi | 2016 | Journal of Environmental Sciences2016，28，2： | 18 |
| 2 | Satellite UV-Vis spectroscopy:implications for air quality trends and their driving forces in China during 2005-2017显示文摘Abundances of a range of air pollutants can be inferred from satellite UV-Vis spectroscopy measurements by using the unique absorption signatures of gas species.Here,we implemented several spectral fitting methods to retrieve tropospheric NO_(2),SO_(2),and HCHO from the ozone monitoring instrument(OMI),with radiative simulations providing necessary information on the interactions of scattered solar light within the atmosphere.We analyzed the spatial distribution and temporal trends of satellite-observed air pollutants over eastern China during 2005-2017,especially in heavily polluted regions.We found significant decreasing trends in NO_(2) and SO_(2) since 2011 over most regions,despite varying temporal features and turning points.In contrast,an overall increasing trend was identified for tropospheric HCHO over these regions in recent years.Furthermore,generalized additive models were implemented to understand the driving forces of air quality trends in China and assess the effectiveness of emission controls.Our results indicated that although meteorological parameters,such as wind,water vapor,solar radiation and temperature,mainly dominated the day-to-day and seasonal fluctuations in air pollutants,anthropogenic emissions played a unique role in the long-term variation in the ambient concentrations of NO_(2),SO_(2),and HCHO in the past 13 years.Generally,recent declines in NO_(2) and SO_(2) could be attributed to emission reductions due to effective air quality policies,and the opposite trends in HCHO may urge the need to control anthropogenic volatile organic compound(VOC)emissions. | Chengxin Zhang Cheng Liu Qihou Hu Zhaonan Cai Wenjing Su Congzi Xia Yizhi Zhu Siwen Wang Jianguo Liu | 2019 | Light(Science & Applications)2019，8，1： | 11 |
| 3 | First observation of tropospheric nitrogen dioxide from the Environmental Trace Gases Monitoring Instrument onboard the GaoFen-5 satellite显示文摘The Environmental Trace Gases Monitoring Instrument(EMI)is the first Chinese satellite-borne UV–Vis spectrometer aiming to measure the distribution of atmospheric trace gases on a global scale.The EMI instrument onboard the GaoFen-5 satellite was launched on 9 May 2018.In this paper,we present the tropospheric nitrogen dioxide(NO2)vertical column density(VCD)retrieval algorithm dedicated to EMI measurement.We report the first successful retrieval of tropospheric NO_(2) VCD from the EMI instrument.Our retrieval improved the original EMI NO_(2) prototype algorithm by modifying the settings of the spectral fit and air mass factor calculations to account for the on-orbit instrumental performance changes.The retrieved EMI NO_(2) VCDs generally show good spatiotemporal agreement with the satellite-borne Ozone Monitoring Instrument and TROPOspheric Monitoring Instrument(correlation coefficient R of ~0.9,bias<50%).A comparison with ground-based MAX-DOAS(Multi-Axis Differential Optical Absorption Spectroscopy)observations also shows good correlation with an R of 0.82.The results indicate that the EMI NO_(2) retrieval algorithm derives reliable and precise results,and this algorithm can feasibly produce stable operational products that can contribute to global air pollution monitoring. | Chengxin Zhang Cheng Liu Ka Lok Chan Qihou Hu Haoran Liu Bo Li Chengzhi Xing Wei Tan Haijin Zhou Fuqi Si Jianguo Liu | 2020 | Light(Science & Applications)2020，9，1： | 11 |
| 4 | Solar influenced late Holocene temperature changes on the northern Tibetan Plateau显示文摘Considerable efforts have been made to extend temperature records beyond the instrumental period through proxy reconstructions,in order to further understand the mechanisms of past climate variability.Yet,the global coverage of existing temperature records is still limited,especially for some key regions like the Tibetan Plateau and for earlier times including the Medieval Warm Period(MWP).Here we present decadally-resolved,alkenone-based,temperature records from two lakes on the northern Tibetan Plateau.Characterized by marked temperature variability,our records provide evidence that temperatures during the MWP were slightly higher than the modern period in this region.Further,our temperature reconstructions,within age uncertainty,can be well correlated with solar irradiance changes,suggesting a possible link between solar forcing and natural climate variability,at least on the northern Tibetan Plateau. | HE YuXin LIU WeiGuo ZHAO Cheng WANG Zheng WANG HuanYe LIU Yi QIN XianYan HU QiHou AN ZhiSheng LIU ZhongHui | 2013 | Chinese Science Bulletin2013，58，9： | 11 |
| 5 | Influences of non-isothermal atmospheric backgrounds on variations of gravity wave parameters显示文摘因为在联合不同大气的区域的重力波浪(GW ) 的重要性,进一步的研究是必要的在非等温的气氛调查 GW 繁殖的特征。用一个非线性的数字模型,我们在不同非等温的气氛与各种各样的波长模仿小振幅 GW 的繁殖。我们的结果证明 GW 垂直波长在 stratopause 和中圈顶区域上面经历锋利的变化。明确地为有 5 km 的起始的垂直波长的 GW,在 50 | LIU Xiao ZHOU QiHou YUAN Wei XU JiYao | 2012 | Science China(Technological Sciences)2012，55，5： | 7 |
| 6 | Role of ammonia in forming secondary aerosols from gasoline vehicle exhaust显示文摘Ammonia(NH3) plays vital roles in new particle formation and atmospheric chemistry. Although previous studies have revealed that it also influences the formation of secondary organic aerosols(SOA) from ozonolysis of biogenic and anthropogenic volatile organic compounds(VOCs), the influence of NH3 on particle formation from complex mixtures such as vehicle exhausts is still poorly understood. Here we directly introduced gasoline vehicles exhausts(GVE) into a smog chamber with NH3 absorbed by denuders to examine the role of NH3 in particle formation from GVE. We found that removing NH3 from GVE would greatly suppress the formation and growth of particles. Adding NH3 into the reactor after 3 h photo-oxidation of GVE, the particle number concentration and mass concentrations jumped explosively to much higher levels, indicating that the numbers and mass of particles might be enhanced when aged vehicle exhausts are transported to rural areas and mixed with NH3-rich plumes. We also found that the presence of NH3 had no significant influence on SOA formation from GVE. Very similar oxygen to carbon(O:C) and hydrogen to carbon(H:C) ratios resolved by aerosol mass spectrometer with and without NH3 indicated that the presence of NH3 also had no impact on the average carbon oxidation state of SOA from GVE. | Tengyu Liu Xinming Wang Wei Deng Yanli Zhang Biwu Chu Xiang Ding Qihou Hu Hong He Jiming Hao | 2015 | Science China Chemistry2015，58，9： | 7 |
| 7 | Comparison of mixing layer height inversion algorithms using lidar and a pollution case study in Baoding, China显示文摘Beijing–Tianjin–Hebei area is suffering from atmospheric pollution from a long time. The understanding of the air pollution mechanism is of great importance for officials to design strategies for the environmental governance. Mixing layer height(MLH) is a key factor influencing the diffusion of air pollutants. It plays an important role on the evolution of heavy pollution events. Light detection and ranging(lidar), is an effective remote-sensing tool, which can retrieve high spatial and temporal evolution process within mixing layer(ML), especially the variation of MLH. There are many methods to retrieve MLH, but each method has its own applicable limitations. The Mie-lidar data in Beijing was firstly used to compare three different algorithms which are widely used under different pollution levels.We find that the multi-layer structure near surface may cause errors in the detection of mixing layer. The MLH retrieved based on image edge detection was better than another two methods especially under heavy polluted episode. Then we applied this method to investigate the evolution of the mixing layer height during a pollution episode in December2016. MLH at Gucheng county showed the positive correlation with the concentration of particulate matters during the start of this pollution episode. The elevated pollution level in Gucheng was not associated with MLH's decrease, and the significantly increased particulate matters raised the boundary layer, which trapped the pollutants near the surface. | Xiangguang Ji Cheng Liu Zhouqing Xie Qihou Hu Yunsheng Dong Guangqiang Fan Tianshu Zhang Chengzhi Xing Zhuang Wang Zeeshan Javed Jianguo Liu | 2019 | Journal of Environmental Sciences2019，31，5： | 5 |
| 8 | Comparison of stratospheric evolution during the major sudden stratospheric warming events in 2018 and 2019显示文摘Using Modern-Era Retrospective analysis for Research and Applications,Version 2(MERRA-2)data in the northern hemisphere at the 10 hPa level,we compared the stratospheric evolution of temperature and geopotential height during two major sudden stratosphere warming events(SSWs)that occurred in the Arctic winter of 2018 and 2019.In the prewarming period,poleward temperature-enhanced regions were mainly located around 120°E with a displaced vortex and around 120°E and 60°W with splitting vortices.The evolution of geopotential height indicated that these temperature-enhanced regions were both on the western side of high-latitude anticyclones.In the postwarming period,the polar vortex turned from splitting to displacement in the 2018 SSW but from displacement to splitting in the 2019 SSW.Both transitions were observed over the Atlantic region,which may have been caused by anticyclones moving through the polar region.Our findings revealed that the evolution of the anticyclone is important during SSWs and is closely related to temperature-enhanced regions in the prewarming periods and to transitions of the polar vortices in postwarming periods. | Zheng Ma Yun Gong ShaoDong Zhang JiaHui Luo QiHou Zhou ChunMing Huang KaiMing Huang | 2020 | Earth and Planetary Physics2020，4，5： | 2 |
| 9 | Removal of arsenic from arsenate complex contained in secondary zinc oxide显示文摘 | Yuhu Li Zhihong Liu Qihou Li Zhongwei Zhao Zhiyong Liu Li Zeng Li Li | 2011 | Hydrometallurgy2011，，3： | 2 |
| 10 | Characteristics of the quasi-16-day wave in the mesosphere and lower thermosphere region as revealed by meteor radar,Aura satellite,and MERRA2 reanalysis data from 2008 to 2017显示文摘This study presents an analysis of the quasi-16-day wave(Q16DW)at three stations in the middle latitudes by using a meteor radar chain in conjunction with Aura Microwave Limb Sounder temperature data and MERRA2(Modern-Era Retrospective Analysis for Research and Applications,Version 2)reanalysis data from 2008 to 2017.The radar chain consists of three meteor radar stations located at Mohe(MH,53.5°N,122.3°E),Beijing(BJ,40.3°N,116.2°E),and Wuhan(WH,30.5°N,114.6°E).The Q16DW wave exhibits similar seasonal variation in the neutral wind and temperature,and the Q16DW amplitude is generally strong during winter and weak around summer.The Q16DW at BJ was found to have secondary enhancement around September in the zonal wind,which is rarely reported at similar latitudes.The latitudinal variations of the Q16DW in the neutral wind and temperature are quite different.The Q16DW at BJ is the most prominent in both neutral wind components among the three stations and the Q16DW amplitudes at MH and WH are comparable,whereas the wave amplitude in temperature decreases with decreasing latitude.The quasi-geostrophic refractive index squared at the three stations in the period from 2008 to 2017 was revealed.The results indicate that the Q16DW in the mesosphere and lower thermosphere(MLT)at MH has a limited contribution from the lower atmosphere.Around March and October,the Q16DW in the troposphere at BJ can propagate upward into the MLT region,whereas at WH,the contribution to the Q16DW in the MLT region is largely from the mesosphere. | Yun Gong Zheng Ma Chun Li XieDong Lv ShaoDong Zhang QiHou Zhou ChunMing Huang KaiMing Huang You Yu GuoZhu Li | 2020 | Earth and Planetary Physics2020，4，3： | 2 |
| 11 | Evaluation and Evolution of MAX-DOAS-observed Vertical NO_(2) Profiles in Urban Beijing显示文摘Multiaxis differential absorption spectroscopy(MAX-DOAS)is a newly developed advanced vertical profile detection method,but the vertical nitrogen dioxide(NO_(2))profiles measured by MAX-DOAS have not yet been fully verified.In this study,we perform MAX-DOAS and tower gradient observations to simultaneously acquire tropospheric NO_(2)observations in the Beijing urban area from 1 April to 31 May 2019.The average values of the tropospheric NO_(2)vertical column densities measured by MAX-DOAS and the tropospheric monitoring instrument are 15.8×1015 and 12.4×1015 molecules cm−2,respectively,and the correlation coefficient R reaches 0.87.The MAX-DOAS measurements are highly consistent with the tower-based in situ measurements,and the correlation coefficients R from the ground to the upper air are 0.89(60 m),0.87(160 m),and 0.76(280 m).MAX-DOAS accurately measures the trend of NO_(2)vertical profile changes,although a large underestimation occurs by a factor of two.By analyzing the NO_(2)vertical profile,the NO_(2)concentration reveals an exponential decrease with height.The NO_(2)vertical profile also coincides with the evolution of the boundary layer height.The study shows that the NO_(2)over Beijing mainly originates from local sources and occurs in the boundary layer,and its vertical evolution pattern has an important guiding significance to better understand nitrate production and ozone pollution. | Yanyu KANG Guiqian TANG Qihua LI Baoxian LIU Jianfeng CAO Qihou HU Yuesi WANG | 2021 | Advances in Atmospheric Sciences2021，38，7： | 2 |
| 12 | Iterative sequences for asymptocfically quasi-nonexpansive mapping with Error Member 显示文摘 | Liu Qihou | 2001 | J Math Anal Appl2001，259，： | 1 |
| 13 | Removal of arsenic from Waelz zinc oxide using a mixed NaOH–Na 2 S leach显示文摘 | Yuhu Li Zhihong Liu Qihou Li Zhongwei Zhao Zhiyong Liu Li Zeng | 2011 | Hydrometallurgy2011，，3： | 1 |
| 14 | Iterative sequences for asymptotically quasi-nonexpansive mappings显示文摘 | | 2001 | Math Anal Appl2001，259，： | 1 |
| 15 | Iterative Sequences for Asymptotically Quasi-nonexpansive Mappings with Error Member显示文摘 | Liu Qihou | 2001 | Journal of Mathematical Analysis and Applications2001，，1： | 1 |
| 16 | A convergent theorem of the sequence of Ishikawa iterates for quasi-contractive mappings显示文摘 | Liu Qihou | 1990 | Math Anal Appl1990，，146： | 1 |
| 17 | A study of the role of ion–molecule chemistry in the formation of sporadic sodium layers显示文摘 | Stephen C. Collins John M.C. Plane Michael C. Kelley Timothy G. Wright Pavel Soldán Timothy J. Kane Andrew J. Gerrard Brent W. Grime Rosie J. Rollason Jonathan S. Friedman Sixto A. González Qihou Zhou Michael P. Sulzer Craig A. Tepley | 2002 | Journal of Atmospheric and Solar-Terrestrial Physics2002，，7： | 1 |
| 18 | Vertical distribution and temporal evolution of formaldehyde and glyoxal derived from MAX-DOAS observations:The indicative role of VOC sources显示文摘Formaldehyde(HCHO)and glyoxal(CHOCHO)are important oxidization intermediates of most volatile organic compounds(VOCs),but their vertical evolution in urban areas is not well understood.Vertical profiles of HCHO,CHOCHO,and nitrogen dioxide(NO_(2))were retrieved from ground-based Multi-Axis Differential Optical Absorption Spectroscopy(MAXDOAS)observations in Hefei,China.HCHO and CHOCHO vertical profiles prefer to occur at higher altitudes compared to NO_(2),which might be caused by the photochemistry-oxidation of longer-lived VOCs at higher altitudes.Monthly means of HCHO concentrations were higher in summer,while enhanced amounts of NO_(2)were mainly observed in winter.CHOCHO exhibited a hump-like seasonal variation,with higher monthly-averaged values not only occurred in warm months(July-August)but also in cold months(November-December).Peak values mainly occurred during noon for HCHO but emerged in the morning for CHOCHO and NO_(2),suggesting that HCHO is stronger link to photochemistry than CHOCHO.We further use the glyoxal to formaldehyde ratio(GFR)to investigate the VOC sources at different altitudes.The lowest GFR value is almost found in the altitude from 0.2 to 0.4 km,and then rises rapidly as the altitude increases.The GFR results indicate that the largest contributor of the precursor VOC is biogenic VOCs at lower altitudes,while at higher altitudes is anthropogenic VOCs.Our findings provide a lot more insight into VOC sources at vertical direction,but more verification is recommended to be done in the future. | Qianqian Hong Cheng Liu Qihou Hu Yanli Zhang Chengzhi Xing Jinping Ou Wei Tan Haoran Liu Xiaoqing Huang Zhenfeng Wu | 2022 | Journal of Environmental Sciences2022，34，12： | 1 |
| 19 | Iterative sequences for asymptotically quasi-nonexpansive mappings with error member显示文摘 | I Liu Qihou | 2001 | J Math Anal Appl2001，259，： | 1 |
| 20 | A convergence theorem of the sequence of ishikawa iterates for uasicontractive mappings显示文摘 | LIU Qihou | 1990 | J Math Anal Appl1990，146，： | 1 |
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