INTEX-B NO2排放源在中国地区的应用与检验

将INTEX-B排放源应用到空气质量模型Model3-CMAQ中,对中国地区对流层NO₂的浓度分布进行了数值模拟,并与OMI卫星对流层NO₂资料进行了对比和验证。结果表明：将INTEX-B排放源应用到Model3-CMAQ模式,模拟的NO₂浓度在中国地区的分布、季节变化规律与卫星资料所得结果一致。敏感性试验表明,工业及电厂排放对NO₂的浓度贡献最大,而交通排放的贡献相对较小,两种排放均主要集中在京津、长江三角洲等经济发达地区。     

INTEX-B NO_2排放源在中国地区的应用与检验

将INTEX-B排放源应用到空气质量模型Model3-CMAQ中,对中国地区对流层NO2的浓度分布进行了数值模拟,并与OMI卫星对流层NO2资料进行了对比和验证。结果表明：将INTEX-B排放源应用到Model3-CMAQ模式,模拟的NO2浓度在中国地区的分布、季节变化规律与卫星资料所得结果一致。敏感性试验表明,工业及电厂排放对NO2的浓度贡献最大,而交通排放的贡献相对较小,两种排放均主要集中在京津、长江三角洲等经济发达地区。     

Environmental Process and Convergence Belt of Atmospheric NO2 Pollution in North China

Both surface environmental monitoring and satellite remote sensing show that North China is one of the regions that are heavily polluted by NO2. Using the NO2 monitoring data from 18 major cities in the region, the tropospheric NO2 column density data from the Ozone Monitoring Instrument (OMI) on the Aura satellite, and the observations from the China Meteorological Administration network, this paper analyzes a regional NO2 pollution event in February 2007 over North China, examines the convergence of the pollutant, and identifies its correlation with the atmospheric background conditions. The results show that daily mean NO2 concentrations derived from surface observations are consistent with the mean values of the OMI measurements, with their correlation coefficient reaching 0.81. The correlations of NO2 concentration with general weather patterns and sequential changes of temperature structure from 925 hPa down to the surface indicate that the weather fronts, high pressure and low pressure systems in the atmosphere play a role in changing the temporal and spatial evolutions of NO2 through removing, accumulating or converging of the pollutant, respectively. It is also found that the eastern Taihang Mountains is most heavily polluted by NO2 in North China. Based on a model that correlates NO2 column density with surface wind vector, the relation of the NO2 concentrations in six major cities in North China to the surrounding wind field is analyzed. The results show that the maximum wind field is associated with the highest frequency of pollution events, and under certain large-scale atmospheric conditions together with the topographic effect, small- and meso-scale wind fields often act to transport and converge pollutants, and become a major factor in forming the heaviest NO2 pollution event in North China. Analysis of the causes for the severe NO2 pollution event in this study may shed light on understanding, forecasting, and mitigating occurrences of heavy NO2 pollution.     

Impact of precursor levels and global warming on peak ozone concentration in the Pearl River Delta Region of China

The relationship between the emission of ozone precursors and the chemical production of tropospheric ozone(O3) in the Pearl River Delta Region(PRD) was studied using numerical simulation.The aim of this study was to examine the volatile organic compound(VOC)-or nitrogen oxide(NOx =NO+NO2)limited conditions at present and when surface temperature is increasing due to global warming,thus to make recommendations for future ozone abatement policies for the PRD region.The model used for this application is the U.S.Environmental Protection Agency’s(EPA’s) third-generation air-quality modeling system;it consists of the mesoscale meteorological model MM5 and the chemical transport model named Community Multi-scale Air Quality(CMAQ).A series of sensitivity tests were conducted to assess the influence of VOC and NOx variations on ozone production.Tropical cyclone was shown to be one of the important synoptic weather patterns leading to ozone pollution.The simulations were based on a tropicalcyclone-related episode that occurred during 14-16 September 2004.The results show that,in the future,the control strategy for emissions should be tightened.To reduce the current level of ozone to meet the Hong Kong Environmental Protection Department(EPD) air-quality objective(hourly average of 120 ppb),emphasis should be put on restricting the increase of NOx emissions.Furthermore,for a wide range of possible changes in precursor emissions,temperature increase will increase the ozone peak in the PRD region;the areas affected by photochemical smog are growing wider,but the locations of the ozone plume are rather invariant.     

SPATIOTEMPORAL VARIATION OF NO2 AND SUB-REGIONAL TRANSPORT DURING WINTER POLLUTION EVENTS IN HAIKOU, CHINA

An ensemble of satellite measurements, statistic data from government and meteorological diagnosis in regional background site (Haikou, China) has revealed the spatial and temporal characteristics of NO2 and associated synoptic transport patterns over southern China from January 2013 to February 2014. The result shows that: (1) Ozone Monitoring Instrument (OMI) satellite products had a good correlation with observation NO2 in Haikou. The correlation coefficients between Observation NO2 and tropospheric column NO2 and ratio of TroNO2/ TotNO2(tropospheric column NO2/ total column NO2) had all passed the confidence level of 99.9% test. (2) TroNO2 over southern China has an obvious seasonal variation, which is closely coupled with regional meteorology in each season. (3) NO2 concentration in Haikou revealed three pollution periods during December 2013 and January 2014. The variation of NO2 concentration in Haikou is related to the meteorological elements closely. (4) Compared to the monthly mean meteorological fields of the pollution periods, the results indicate that NO2 pollution event in Haikou is directly related to the exogenous transportation from PRD region. An ensemble analysis of meteorological dynamic factors, wind vectors and backward trajectories during the pollution periods further verified this conclusion.     

基于OMI数据的贵州省对流层NO2浓度时空变化分析

利用OMI卫星遥感数据提供的NO2浓度产品及气象站点数据,分析了2005-2017年贵州省对流层NO2柱浓度时空分布特征及其影响因素。结果表明:①贵州省NO2柱浓度年均值较小,说明贵州省空气质量整体比较好,年变化为NO2柱浓度先升高再降低的趋势,冬季最高、夏季最低,而月变化呈内凹型分布,一年中最大值大多出现在1月,7月出现最低值的次数最多;②空间分布呈西高东低、北高南低的特点;③在9个地市州中,六盘水市的NO2柱浓度年均值最大,贵阳市位于第二,浓度最低的是黔东南州。④降水和温度对NO2柱浓度都具有一定的负影响。     

Global financial crisis making a V-shaped fluctuation in NO<Subscript>2</Subscript> pollution over the Yangtze River Delta

The Yangtze River Delta (YRD), China’s main cultural and economic center, has become one of the most seriously polluted areas in the world with respect to nitrogen oxides (NO_x), owing to its rapid industrialization and urbanization, as well as substantial coal consumption. On the basis of nitrogen dioxide (NO₂) density data from ozone monitoring instrument (OMI) and ground-based observations, the effects of industrial fluctuations due to the financial crisis on local NO₂ pollution were quantitatively assessed. The results were as follows. (1) A distinct V-shaped fluctuation of major industrial products, thermal generating capacity, electricity consumption, and tropospheric NO₂ densities was associated with the global financial crisis from May 2007 to December 2009, with the largest anomalies 1.5 times more than standard deviations at the height of the crisis period from November 2008 to February 2009. (2) Among all industrial sectors, thermal power plants were mainly responsible for fluctuations in local NO₂ pollution during the crisis period. Thermal generating capacity had its greatest decrease of 12.10% at the height of the crisis compared with that during November 2007–February 2008, leading to local tropospheric NO₂ density decreasing by 16.97%. As the crisis appeased, thermal generating capacity increased by 29.63% from November 2009 to February 2010, and tropospheric NO₂ densities correspondingly increased by 30.07%. (3) Among all industrial sectors in the YRD, the thermal power sector has the greatest coal consumption of about 65.96%. A decline in thermal power of about 10% can induce a decrease of about 30% in NO_x emissions and NO₂ densities, meaning that a relative small fluctuation in industrial production can lead to a large decrease in tropospheric NO₂ densities over industrially developed areas like the YRD region. Since electricity is mainly obtained from local coal-burning thermal plants without NO_x-processing equipment, installing NO_x-removal devices for all thermal power plants is an important and feasible way of controlling local NO_x pollution at present.     

A numerical study of the influence of urban expansion on monthly climate in dry autumn over the Pearl River Delta, China

Summary In this study, we employed a regional model to simulate the impact of urban expansion on monthly climate in Pearl River Delta (PRD) region. Two experiments were performed by prescribing two different land covers in the PRD region. One land cover represents vegetation in the 1970s which is derived from the United States Geological Survey (USGS) data with 24-category (hereafter referred to as NU). The other land cover represents the current urban condition which is derived from remote sensing data acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS) in 2004 (hereafter referred to as HU). Using the two land cover datasets, monthly climate of October 2004 was simulated, which was a very dry season in the PRD region. The results obtained from the numerical simulation show a distinct difference in simulated shelter-level temperature, humidity, surface fluxes and the height of planetary boundary layer (PBL) with two different land cover data sets being specified. The maximum difference in simulated monthly mean temperature over urban areas was 0.9 °C. A large temperature difference was found in urbanized area in Guangzhou, Dongguan, Zhongshan and Shenzhen. The monthly mean relative humidity in urban areas decreased by 1.4% as a result of urban expansion (from 59.2% in NU to 57.8% in HU). The maximum decrease in mixing ratio was 0.4 g/kg in Guangzhou and Dongguan, whereas the maximum decrease in relative humidity was 2.4%. There was an increase of sensible heat flux in developed lands and the maximum increase was 90 W m⁻². In contrast, latent hear flux in urban area decreased and the maximum decrease was 300 W m⁻². In addition, the increase in mean height of PBL ranged from 20 to 80 m (HU compared with NU), and the maximum change of the height was 180 m over urban area in city of Guangzhou.     

新冠疫情影响下全球对流层臭氧变化特征研究进展

自2020年新冠疫情(COVID-19)爆发以来,各地进行了不同程度的人员流动限制或封控,致使全球范围内氮氧化物(NO_x)、二氧化硫(SO₂)、一氧化氮(CO)、细颗粒物(PM2.5)等大气污染物浓度均大幅度降低,而作为二次污染物的臭氧(O₃)在各地区却表现出复杂的变化特征,成为研究热点。本研究总结了近两年该方向的研究成果,阐明了COVID-19期间对流层O₃及其前体物的变化特征、变化机制及其可能存在的潜在环境效应。COVID-19严控期,全球人为NO_x排放下量降了至少15%,特别是高人为活动影响区,下降了18%～25%,部分高污染地区(挥发性有机物敏感区)近地层NO_x的减少量达50%以上。NO_x的减少导致NO对O₃的滴定作用减弱,使得该类高污染地区O₃增加(10%～50%)。而偏远地区及自由对流层O₃主要受NO_x控制,NO_x...     

基于WRF模式的京津冀地区地表大气CO2浓度的模拟研究

在“双碳”目标背景下，从国家层面到地方层面，区域、城市、行业企业都在制定和实施双碳目标行动计划。CO₂模拟因其客观性和高时空分辨率等优势，在城市碳排放研究中深受重视。本研究以京津冀地区为研究区域，采用Picarro仪器高精度观测的2019—2020年CO₂数据，利用WRF模式进行CO₂传输模拟，分析了CO₂浓度变化的季节特征，评估了模式在城区中心、城郊及背景3个观测站点的模拟效果，并对边界层高度及化石燃料碳排放等可能影响CO₂浓度的因素进行了研究。3个观测站点分别为北京中国科学院大气物理研究所325 m气象塔观测站（北京站）、河北香河观测站（香河站）和上甸子区域本底观测站（上甸子站）。模拟结果表明：上甸子站优于香河站，香河站优于北京站，在冬季尤其明显；CO₂浓度的高值区主要分布在城区、电厂和工业区，尤其是唐山、石家庄和邯郸地区，大量交通、工业排放导致CO₂浓度明显上升，且高值区的范围在冬季最大；就日平均变化和日变化而言，边界层高度与CO₂浓度存在相反变化趋势；3个站点的化石燃料碳排放（FFECO2）与近地面总CO₂浓度存在正相关关系，冬春季的相关性高于夏秋季，且FFECO2的占比从大到小依次为北京站、香河站、上甸子站；CO₂传输模拟的不确定性存在空间差异和季节变化。     

The climate change mitigation impacts of active travel: Evidence from a longitudinal panel study in seven European cities

Active travel (walking or cycling for transport) is considered the most sustainable and low carbon form of getting from A to B. Yet the net effects of changes in active travel on changes in mobility-related CO₂ emissions are complex and under-researched. Here we collected longitudinal data on daily travel behavior, journey purpose, as well as personal and geospatial characteristics in seven European cities and derived mobility-related lifecycle CO₂ emissions over time and space. Statistical modelling of longitudinal panel (n = 1849) data was performed to assess how changes in active travel, the ‘main mode’ of daily travel, and cycling frequency influenced changes in mobility-related lifecycle CO₂ emissions.We found that changes in active travel have significant lifecycle carbon emissions benefits, even in European urban contexts with already high walking and cycling shares. An increase in cycling or walking consistently and independently decreased mobility-related lifecycle CO₂ emissions, suggesting that active travel substituted for motorized travel – i.e. the increase was not just additional (induced) travel over and above motorized travel. To illustrate this, an average person cycling 1 trip/day more and driving 1 trip/day less for 200 days a year would decrease mobility-related lifecycle CO₂ emissions by about 0.5 tonnes over a year, representing a substantial share of average per capita CO₂ emissions from transport. The largest benefits from shifts from car to active travel were for business purposes, followed by social and recreational trips, and commuting to work or place of education. Changes to commuting emissions were more pronounced for those who were younger, lived closer to work and further to a public transport station.Even if not all car trips could be substituted by active travel the potential for decreasing emissions is considerable and significant. The study gives policy and practice the empirical evidence needed to assess climate change mitigation impacts of urban transport measures and interventions aimed at mode shift to more sustainable modes of transport. Investing in and promoting active travel whilst ‘demoting’ private car ownership and use should be a cornerstone of strategies to meet ‘net zero’ carbon targets, particularly in urban areas, while also reducing inequalities and improving public health and quality of urban life in a post-COVID-19 world.     

Source Contributions to PM_(2.5) under Unfavorable Weather Conditions in Guangzhou City,China

Historical haze episodes(2013–16) in Guangzhou were examined and classified according to synoptic weather systems.Four types of weather systems were found to be unfavorable, among which "foreside of a cold front"(FC) and "sea high pressure"(SP) were the most frequent( 75% of the total). Targeted case studies were conducted based on an FC-affected event and an SP-affected event with the aim of understanding the characteristics of the contributions of source regions to fine particulate matter(PM_(2.5)) in Guangzhou. Four kinds of contributions—namely, emissions outside Guangdong Province(super-region), emissions from the Pearl River Delta region(PRD region), emissions from Guangzhou–Foshan–Shenzhen(GFS region), and emissions from Guangzhou(local)—were investigated using the Weather Research and Forecasting–Community Multiscale Air Quality model. The results showed that the source region contribution differed with different weather systems. SP was a stagnant weather condition, and the source region contribution ratio showed that the local region was a major contributor(37%), while the PRD region, GFS region and the super-region only contributed 8%, 2.8% and 7%, respectively, to PM_(2.5) concentrations. By contrast, FC favored regional transport. The super-region became noticeable,contributing 34.8%, while the local region decreased to 12%. A simple method was proposed to quantify the relative impact of meteorology and emissions. Meteorology had a 35% impact, compared with an impact of-18% for emissions, when comparing the FC-affected event with that of the SP. The results from this study can provide guidance to policymakers for the implementation of effective control strategies.     

The impacts of urbanization on air quality over the Pearl River Delta in winter: roles of urban land use and emission distribution

In this study, ideal but realistic numerical experiments are performed to explore the relative effects of changes in land use and emission distribution on air quality in the Pearl River Delta (PRD) region in winter. The experiments are accomplished using the Lagrangian particle transport and dispersion model FLEXPART coupled with the Weather Research and Forecasting model under different scenarios. Experiment results show that the maximum changes in daily mean air pollution concentration (as represented by SO₂ concentration) caused by land use change alone reaches up to 2?×?10^?6 g m^?3, whereas changes in concentrations due to the anthropogenic emission distribution are characterized by a maximum value of 6?×?10^?6 g m^?3. Such results reflect that, although the impacts of land use change on air quality are non-negligible, the emission distribution exerts a more significant influence on air quality than land use change. This provides clear implications for policy makers to control urban air pollution over the PRD region, especially for the urban planning in spatial arrangements for reasonable emissions.     

城市遥感研究进展

城市遥感是当前遥感技术应用的一个重要领域.随着我国新型城镇化过程的推进,遥感技术将在城市生态建设、国土空间开发、资源环境承载能力监测等方面发挥重要作用,成为城市规划管理重要的信息源.本文在总结国内外城市遥感研究内容的基础上,重点对城市遥感若干重要方向的发展进行了分析,在此基础上构建出一个地理学视角的城市遥感研究框架,结合典型实例从结构与格局、要素与作用、变化与过程、功能与响应4个方面进一步探讨了城市遥感研究的发展.最后,结合国家需求和技术发展,对城市遥感今后的发展从数据源、研究对象、应用主题、研究目标、技术方法等方面进行了展望.     

利用卫星资料分析对流层臭氧柱总量分布特征及其可能的原因

利用卫星资料计算得到的对流层臭氧柱总量数据分析了近20年来全球对流层臭氧柱总量的全球分布特征，并对我国对流层臭氧的季节变化做了研究。利用对流层污染测量仪（MOPITT）的CO和全球臭氧监测仪（GOME）和大气制图扫描成像吸收光谱仪（SCIAMACHY）的NO₂数据分析了关于对流层臭氧的分布特征及其原因。得出中高纬度地区对流层臭氧浓度存在规律的年内变化，对流层臭氧高浓度值的分布及变化与人类活动有密切关切。     

Tracking emission sources of sulfur and elemental carbon in Hong Kong/Pearl River Delta region

The Tagged Species Source Apportionment (TSSA) algorithm is applied to study contributions to pollutants PM sulfate, SO2 and elemental carbon (EC) in Hong Kong by emitting sectors as well as non-emitting sources within and beyond the Pearl River Delta (PRD) region. We look at three areas of Hong Kong: western new towns, central downtown, and eastern countryside. Pollutant transport from beyond the PRD influenced all three areas during January and October 2004 but the source sectors impacting the three areas were different. Specifically, power plant SO2 from Hong Kong and Shenzhen, and vehicle EC from Shenzhen contribute to 11?~?66?% of SO2 concentration, and 33?~?75?% of EC concentration in the western new towns, respectively. Ships in and around Hong Kong contribute 8?~?56?% to the sulfate concentration in the downtown area, while local moving vehicles take up 28?~?81?% of the EC concentration there. The study also shows that diurnal variation of planetary boundary layer (PBL) causes day-night difference in SO2 by as much as 50?%. In addition, 13?~?38?% of all SO2 emissions have been converted to PM sulfate.     

Environmental process and convergence belt of atmospheric NO2 pollution in North China

Both surface environmental monitoring and satellite remote sensing show that North China is one of the regions that are heavily polluted by NO₂. Using the NO₂ monitoring data from 18 major cities in the region, the tropospheric NO₂ column density data from the Ozone Monitoring Instrument (OMI) on the Aura satellite, and the observations from the China Meteorological Administration network, this paper analyzes a regional NO₂ pollution event in February 2007 over North China, examines the convergence of the pollutant, and identies its correlation with the atmospheric background conditions. The results show that daily mean NO₂ concentrations derived from surface observations are consistent with the mean values of the OMI measurements, with their correlation coeficient reaching 0.81. The correlations of NO₂ concentration with general weather patterns and sequential changes of temperature structure from 925 hPa down to the surface indicate that the weather fronts, high pressure and low pressure systems in the atmosphere play a role in changing the temporal and spatial evolutions of NO₂ through removing, accumulating or converging of the pollutant, respectively. It is also found that the eastern Taihang Mountains is most heavily polluted by NO₂ in North China. Based on a model that correlates NO₂ column density with surface wind vector, the relation of the NO₂ concentrations in six major cities in North China to the surrounding wind field is analyzed. The results show that the maximum wind field is associated with the highest frequency of pollution events, and under certain large-scale atmospheric conditions together with the topographic effect, small- and meso-scale wind fields often act to transport and converge pollutants, and become a major factor in forming the heaviest NO₂ pollution event in North China. Analysis of the causes for the severe NO₂ pollution event in this study may shed light on understanding, forecasting, and mitigating occurrences of heavy NO₂ pollution.     

Responses of the tropospheric ozone and odd hydrogen radicals to column ozone change

The response of tropospheric ozone to a change in solar UV penetration due to perturbation on column ozone depends critically on the tropospheric NO _x (NO+NO₂) concentration. At high NO _x or a polluted area where there is net ozone production, a decrease in column ozone will increase the solar UV penetration to the troposphere and thus increase the tropospheric ozone concentration. However, the opposite will occur, for example, at a remote oceanic area where NO _x is so low that there is net ozone destruction. This finding may have important implication on the interpretation of the long term trend of tropospheric ozone. A change in column ozone will also induce change in tropospheric OH, HO₂, and H₂O₂ concentrations which are major oxidants in the troposphere. Thus, the oxidation capacity and, in turn, the abundances of many reduced gases will be perturbed. Our model calculations show that the change in OH, HO₂, and H₂O₂ concentrations are essentially independent of the NO _x concentration.     

基于MODIS影像的色林错湖面积变化及成因

利用2002-2009年EOS/MODIS卫星遥感资料和气温、地表温度气象资料,对色林错湖面积变化进行分析,并探讨了其成因.结果表明:西藏那曲地区色林错湖(包括雅根错湖)面积在近8 a呈显著的扩大趋势,从2002年的1955.49 km2增至2009年的2197.46km2,8 a内增长了24197 km2,现已超过纳...     

华北平原固城站NO2对流层柱浓度变化特征

基于2008年9月—2010年9月河北固城生态与农业气象试验站多轴差分吸收光谱仪 (multi-axis differential optical absorption spectroscopy, MAX-DOAS) 获得的太阳散射光谱观测,反演计算该地区NO₂对流层柱浓度,分析其季节、日变化特征以及不同来源输送的影响,并与同期NO₂地面观测资料和卫星产品进行对比分析。发现固城站NO₂对流层柱浓度冬高 (5.14×1016 cm-2) 夏低 (1.28×1016 cm-2);日变化形态在四季均呈现中午低、傍晚高的特征,且冬季最明显。与北京城市区域同期的观测相比,冬季固城站观测值略低,而在春、夏季则偏低较显著。地面风玫瑰图分析显示,来自SW, SSW, NE方向及ENE方向的污染输送对其贡献最大。与地面、卫星NO₂观测的对比表明,MAX-DOAS反演的NO₂柱浓度与地面观测浓度具有一致的季节和日变化特征,卫星反演的NO₂对流层柱浓度产品在华北平原农村地区存在系统性低估。