Integration of Multi-source Measurements to Monitor Dust over North China：A Case Study

The aerosol optical depth （AOD） data from the Moderate Resolution Imaging Spectroradiometer （MODIS） aboard Satellite Aqua, along with the altitude-resolved aerosol subtypes product from the Cloud-Aerosol LIdar with Orthogonal Polarization （CALIOP）, as well as surface PM 10 measurements, were utilized to investigate the dust activities common in springtime of northern China. Specifically, a dust storm episode that occurred over the North China Plain （NCP） during 17-21 March 2010 was identified. The PM 10 concentration at Beijing （39.8 °N, 116.47 °E） reached the peak value of 283 μgm -3 on 20 March 2010 from the background value of 15 μg m-3 measured on 17 March 2010, then dropped to 176 μgm-3 on 21 March 2010. Analysis of the CALIOP aerosol subtypes product showed that numerous large dust plumes floated over northern China, downwind of main desert source regions, and were lifted to altitudes as high as 3.5 km during this time period. The MODIS AOD data provided spatial distributions of dust load, broadly consistent with ground-level PM 10 , especially in cloud free areas. However, inconsistency between the MODIS AOD and surface PM 10 measurements under cloudy conditions did exist, further highlighting the unique capability of the CALIOP lidar. CALIOP can penetrate the cloud layer to give unambiguous and altitude-resolved dust measurements, albeit a relatively long revisit period （16 days） and narrower swath （90 m）. A back trajectory simulation using the Hybrid Single-Particle Lagrangian Integrated Trajectory （HYSPLIT） model was performed, and it was found that the sand-dust storm originated from the Gobi Desert on 18 March 2010 travelled approxi-mately 1200-1500 km day-1 eastward and passed over the NCP on 19 March 2010, in good agreement with previous findings. In addition, the multi-sensor measurements integrated with the HYSPLIT model output formed a three-dimensional view of the transport pathway for this dust episode, indicating that this episode was largely associated with the desert source regions to the northwest of the NCP. The results imply the importance of integration of multi-sensor measurements for clarifying the overall structure of dust events over northern China.     

长三角工业区夏季近地层臭氧和颗粒物污染相互关系研究

利用2013年5月15日到8月31日南京江北工业区（长三角典型工业区）同步的观测资料分析了近地层臭氧（O₃）和细颗粒物（PM_2.5）、气溶胶光学厚度（AOD）的变化特征及相互间的关系,并结合光化学箱模式分析了AOD对近地层O₃生成的影响。结果表明,观测期间PM_2.5平均质量浓度为56.2±20.1 μg m-3;AOD（500 nm）均值为1.4±0.9;波长指数α（440~870 nm）均值为1.0±0.3。PM_2.5质量浓度24 h均值超国家二级标准20.2%,超标时AOD均值增加14.7%,α平均值增加23.9%,O₃体积分数均值减少12.3%。O₃超国家二级标准10.1%,超标时段AOD增加34.9%,α变化不显著。高温低湿条件下,O₃日变化峰值（y）和PM_2.5质量浓度（x）存在较高的线性相关。相对湿度＜60%时,两者拟合曲线为y＝0.97x+43.96（拟合度R2=0.60）,温度＞32°C时,两者拟合方程为y＝1.24x+30.61（R2＝0.64）。夏季长三角工业区呈现高浓度O₃与高浓度PM_2.5叠加的大气复合污染。O₃日变化峰值和AOD变化呈显著负相关。模拟结果显示,O₃日变化峰值（y）和AOD（x）呈现极高的负相关[y＝－34.28x+181.62,R2 = 0.93或y＝220.62·exp (－x/3.17)－19.50,R2＝0.99]。     

广州地区旱季一次典型灰霾过程的特征及成因分析

通过研究2009年11月广州市气溶胶颗粒物质量浓度(PM10、PM2.5、PM1)、黑碳浓度、散射系数(Scatter)等大气成分要素,以及微波辐射计、激光雷达及风廓线雷达所探测的风、温、湿等边界层结构,统计分析广州旱季一次典型灰霾过程(2009年11月23—29日)中气溶胶颗粒物及其光学特性的时空变化特征,并配合天气形势背景、边界层结构对其形成原因进行详细分析。在典型灰霾过程中,黑碳浓度高达58.7μg/m3,散射系数高达1 902.7 Mm-1,PM10浓度高达423.5μg/m3,PM2.5浓度高达355.7μg/m3,PM1浓度高达286.5μg/m3。通过对同期的气象条件分析表明在广州地区旱季,区域性污染过程,特别是灰霾天气的形成具有以下三种气象条件:大气边界层高度较低;高压变性出海的天气形势与之密切相关;在偏东和偏南气流带来的高湿度环境下,气溶胶吸湿增长效应显著,导致出现严重灰霾天气。     

深圳市龙华新区PM2．5质量浓度分布特征及来源分析

通过对龙华新区2个监测站点2012年的PM2．5监测数据进行分析,得出新区PM2．5年均质量浓度值为0．043mg／m^3,全年总超标天数为30d,超标率为8．2％。PM2．5污染具有明显的季节性特征,干季污染严重,雨季则较轻。新区常年盛行偏北风,处于东莞、惠州等污染严重区域的下风向,且风速偏小,是新区PM2．5来源及质量浓度升高的重要原因之一。同时,利用大气环境影响评价系统的AERMOD模型对新区PM2,污染质量浓度分布进行模拟,结果显示新区PM2．5主要来自本地污染源,贡献率为51．2％,外地污染源贡献率为48．8％。其中,PM2．5污染主要受机动车尾气和道路扬尘影响,贡献率为32．0％,其次是施工项目和裸露土地影响,贡献率为18．2％,工业污染源影响非常小。     

中国的PM2.5和对流层臭氧及污染物排放控制对策的综合分析

本文首先对中国PM2.5和近地面臭氧浓度的观测进行了简要的综述;并利用2010-2013年全球对流层臭氧的卫星观测数据给出了对流层臭氧浓度在全球和中国地区的分布特征,其平均值分别为29.78 DU和33.97 DU。然后,利用一个气溶胶大气化学-全球气候双向耦合模式模拟了中国地区PM2.5的浓度分布和季节变化,其年平均值为0.51×10^-8 kg/m³。在此基础上又分析了5种典型气溶胶对PM2.5总浓度在不同季节的贡献。结合IPCC第五次评估报告（AR5）,讨论了气溶胶和温室气体及其前体物的排放与辐射强迫的联系,以及减排大气臭氧前体物和气溶胶颗粒物质（PM）对气候变化的可能影响。指出减排臭氧前体物对气候的影响还不完全清楚,对短寿命的温室气体和黑碳气溶胶的减排是一种短期（未来50年）的辅助措施;为了保证全球平均温度增长不超过2℃,减少二氧化碳的排放仍是我们需要坚持的长期战略。短期和长期的减排战略对于保护环境和减缓气候变化都是至关重要的。     

邢台沙河市冬季大气污染特征与潜在源区分析

为了解邢台沙河市冬季大气污染特征,选取2017年12月至2018年2月沙河市区3个省控站点（司法局、市政府、宣传中心）的逐时监测数据,分析了沙河市主要污染物的时空分布特征和潜在源区。污染物浓度特征分析表明:整个冬季司法局、市政府和宣传中心站点的细颗粒物（PM2.5）平均浓度分别为118.0 μg/m3、121 μg/m3和135 μg/m3。在大气自然活动和人为污染排放的共同作用下,PM10、PM2.5、SO₂、NO₂和CO均有明显的日变化特征。整个冬季沙河市的ρ(PM2.5)/ρ(PM10)、ρ(SO₂)/ρ(NO₂)均值分别为0.57和1.05（ρ为各物质的浓度）。且随着污染加重,ρ(PM2.5)/ρ(PM10)、ρ(SO₂)/ρ(NO₂)均明显升高,表明燃煤贡献增加;污染物空间分布特征分析表明:位于3个站点东北处的玻璃企业产生的污染物可能对监测站点造成了一定影响。污染物空间差异分析表明,区域污染范围越大、强度越高,大气污染的空间差异性越小;潜在源分析表明:沙河市PM2.5的强潜在源区分布在其周边区域,随着PM2.5浓度增加,强潜在源区呈缩小趋势。沙河市东南部的本地源对PM2.5浓度有主要贡献,而此处正是玻璃企业的聚集地。     

2018年春季西北五省省会城市大气质量与健康风险评价

城市大气污染及其引起的健康效应一直是关注的热点.本研究对2018年春季西北五省省会城市PM2.5、PM10、NO2、SO2、CO和O3浓度数据进行了系统分析,并采用美国环境保护署(United States Envi-ronmental Protection Agency,USEPA)推荐的健康风险评价模型评估了PM2...     

吐鲁番市颗粒物浓度变化特征及与气象要素的关系

依据吐鲁番市2015年3月—2016年2月的PM_(10)、PM_(2.5)和气象资料,利用统计分析,探讨吐鲁番市PM_(10)和PM_(2.5)浓度的变化特征及其与气象要素的关系。结果表明:冬季PM2.5与PM10浓度的平均值最高(106 ug/m3、184 ug/m~3),春季次之(63 ug/m~3、163 ug/m~3),夏季最低(33 ug/m~3、95ug/m~3),且冬季二者浓度的平均值比夏季分别高大约69%、48%。11月至次年2月,每个月中PM_(2.5)和PM_(10)的污染程度在轻度污染以上的天数相比其它月份较多。PM_(10)与PM_(2.5)的日变化曲线特征呈现"双峰双谷"的特点;PM_(2.5)与PM_(10)的比值在冬季达到了60%~80%,这说明吐鲁番冬季主要以PM2.5污染为主;PM_(2.5)和PM_(10)与能见度之间存在极其显著的相关性,相关系数分别为-0.904、-0.792,与单一气象要素(如相对湿度、风速、温度等)的相关性不明显,但不同气象要素的共同作用对其有显著影响。     

Factors affecting levels of aerosol sulfate and nitrate on the Western Mediterranean coast

The present study was carried out between October 2003 and September 2004 at an urban background station near the Mediterranean coast in southeastern Spain. The sulfate and nitrate content was determined in 332 PM10 and PM2.5 daily samples. The results show that the seasonal variation of nitrate measured in PM10 does not correspond with what has been observed at other locations in the Iberian Peninsula, where the minima are reached during the summer months due to decomposition of ammonium nitrate at high temperatures. The recorded levels of PM10 nitrate were slightly higher in summer due to an increase in the concentrations of coarse mode nitrate. On the contrary, both the concentrations and the percentages of nitrate in PM2.5 were lowest from June to September. The sulfate levels in both PM10 and PM2.5 were maxima in summer because the oxidation rate of SO₂ increases with solar radiation. An elevated correlation (0.72 < r < 0.92) between the monthly average concentrations and percentages of sulfate and solar radiation has been found. We have also investigated the influence that Saharan dust intrusions and high pollution episodes have upon the sulfate and nitrate concentrations. Both types of events increased NO₃⁻ and SO₄²⁻ levels, particularly the high pollution episodes.     

敦煌莫高窟大气颗粒物中水溶性离子变化及来源解析

为探明莫高窟大气颗粒物污染特征,采集了2014年4-12月第16窟及72窟外环境中大气颗粒物PM2.5和PM10～2.5样品,对比分析了样品中水溶性离子变化及影响因素,通过主成分分析法解析了其主要来源.结果表明:(1)窟区主风向为南风,起沙风频率仅为0.01％,不利于污染物的扩散;(2)窟外PM2.5和PM10～2.5...     

冬季采暖优化对北京地区空气质量的影响

空气污染能够影响人体健康、交通运输、农业生产等,会对国家经济造成损失.多年来,北京一直是空气污染严重地区,而冬季燃煤采暖是一个重要的原因.2016～2017年,北京大力优化采暖的能源结构,旨在改善空气质量.本文通过分析5个位于北京不同区域的空气质量监测站的PM2.5、PM10、SO2、 NO2和CO污染物浓度,对比了2...     

基于数值模拟和统计拟合分析华北冬季一次大范围重污染过程的形成机理

基于WRF/Chem（Weather Research Forecasting/Chemistry）模式对2015年11月25日至12月2日我国北方一次大范围PM2.5（空气动力学当量直径小于等于2.5 μm的颗粒物,即细颗粒物）重污染过程进行了模拟。与观测资料对比表明,模式能够较好地模拟出PM2.5浓度及气象因素的变化趋势,结果适用于此次污染事件的机理分析。动力、热力条件及化学转化等因素对此次强污染事件形成的机理分析表明,动力因子主要通过表面风和垂直风切变的减弱对此次污染事件造成影响,边界层逆温等热力因子促进了大气稳定性的增强,不利于污染物扩散。依据PM2.5组成成分变化分析可知,硝酸盐、硫酸盐和有机碳在此次事件中含量增加,说明机动车汽车尾气和燃煤排放所致的二次气溶胶生成对PM2.5污染加剧起重要贡献。多元线性回归分析和多因子相对贡献率量化解析结果表明,热力因子在此次污染过程中起主要作用,方差贡献率为52%,动力因子次之,方差贡献率为34%,而化学转化方差贡献率约为14%,说明气象条件,尤其是热力条件是引起此次污染事件的主要原因。     

An analysis on the concentration characteristics of PM2.5 in Seoul,Korea from 2005 to 2012

PM2.5 is a big issue as it is considerably more harmful than other sizes of particulate matter. World Health Organization (WHO) recommends 25 μg m^?3 as the daily average concentration, and 10 μg m^?3 per day as an annual average. To keep up with global trends, it is first necessary to understand the current status and characteristics of PM2.5 concentrations in Korea. Using the PM2.5 data measured by Seoul Metropolitan City from November 2005 to March 2012, the author analyzed its statistical characteristics and correlations with other air pollutants. For the time period from 2005 to 2012, the annual average concentration of PM2.5 was 27 μg m^?3, three times the WHO standard. Also, the daily average PM2.5 concentration of 215 days per year also exceeded the WHO standard. However, the number days exceeding the Korean daily average standard of 50 μg m^?3 to be enacted in 2014 was only three. PM2.5 concentration had a high correlation (r = 0.84) with PM10, and also showed high correlations with gaseous pollutants, such as SO₂, NO₂, and CO, but not O₃. This study suggests that the Korean government should strengthen their standard to match the criteria used by WHO.     

苏州市能见度与影响因子关系研究

利用2009年6月—2010年5月苏州市气象局霾监测点颗粒物浓度、能见度、相对湿度、风速、风向、气温等观测资料,分析了苏州能见度变化特征,建立了能见度和影响因子的统计模型,研究了能见度和气象因子及颗粒物浓度的关系。结果表明：苏州市能见度有明显的季节变化,春季能见度最好,秋季能见度最低;能见度日变化显著,最低能见度通常出现在清晨,午后明显好转;PM10、PM2.5、黑碳浓度值和相对湿度与能见度都呈反相关关系,但黑碳对能见度的影响不如PM10和PM2.5对能见度的影响明显;风速与能见度呈正相关关系,在东南、南东南风向时能见度值最高。     

Characteristics of Gaseous Pollutants at a Regional Background Station in Southern China

Measurements of gaseous pollutants （03, NOx, SO2, and CO） were conducted at Dinghushan background station in southern China from January to December 2013. The levels and variations of O3, NOx, SO2, and CO were analyzed and their possible causes discussed. The annual average concentrations of 03, NOx, SO2, and CO were 24.6 ± 23.9, 12.8 ± 10.2, 4.0 ± 4.8, and 348 ± 185 ppbv, respectively. The observed levels of the gaseous pollutants are comparable to those at other background sites in China. The most obvious diurnal variation of 03 was observed in autumn, with minima in the early morning and maxima in the afternoon. The diurnal variations of SO2 showed high values during the day. The diurnal cycles of NOx showed higher values in the morning and lower values during the night. Higher CO concentrations were observed in spring followed by winter, autumn, and summer. Biomass burning, in combination with the transport of regional pollution, is an important source of CO, SO2, and NOx in spring and winter. Backward trajectories were calculated and analyzed together with corresponding pollutant concentrations. The results indicate that air masses passing over polluted areas are responsible for the high concentrations of gaseous pollutants at the Dinghushan background station.     

秸秆燃烧对北京秋季气溶胶浓度和短波辐射影响的模拟研究

利用地面细颗粒物（PM2.5）浓度和气象常规观测资料、地基 AERONET观测资料、GFED生物质燃烧排放清单和大气化学—天气耦合模式WRF-Chem,模拟研究了华北地区2014年10月气象要素和大气污染物的时空演变,重点关注北京10月7～11日的一次重霾事件及其天气形势、边界层气象特征、输送路径、PM2.5及其化学成分浓度变化等特征,以及秸秆燃烧对华北和北京地区细颗粒物浓度和地面短波辐射的影响。与观测资料的对比结果显示,模式可以很好地模拟北京地区地面气象要素和PM2.5质量浓度,考虑秸秆燃烧排放源可以明显改进北京PM2.5浓度模拟的准确性,但在重度污染情况下,模式总体上低估气溶胶光学厚度和高估地面短波辐射。10月7～11日北京地区重霾事件主要是不利气象条件下人为污染物累积和区域输送造成,也受到华北地区南部秸秆燃烧的影响。河南北部、河北南部和山东西部大面积秸秆燃烧释放的气态污染物和颗粒物在南风的作用下输送至北京,秸秆燃烧对北京地区地面PM2.5、有机碳（OC）、硝酸盐、铵盐、硫酸盐和黑碳（BC）的平均贡献率分别为24.6%、36.8%、23.2%、22.6%、7.1%和19.8%,秸秆燃烧产生的气溶胶可以导致北京地面平均短波辐射最大减小超过20 W m－2,约占总气溶胶导致地表短波辐射变化的24%。     

烟花爆竹燃放对天津市空气质量的影响研究

为了研究烟花爆竹燃放对空气质量的影响,利用动态滤膜校准系统-微量震荡天平法颗粒物分析仪、大气细颗粒化学组分在线离子色谱监测仪、有机碳（OC）/元素碳（EC）在线分析仪、气态污染物分析仪、常规自动气象站并结合云高仪和微波辐射计等设备于2015年2月18日至3月7日对天津市细颗粒物（PM2.5）及其主要化学组分,气态污染物（SO₂、NO₂、CO和O₃）和气象参数进行连续观测。本文选取3个污染事件作为研究重点进行分析,研究发现:烟花爆竹禁放和限放政策导致除夕夜烟花爆竹燃放量减少,PM2.5峰值与2014年相比明显下降;烟花爆竹禁放和限放区的设立导致天津市PM2.5质量浓度在烟花爆竹密集燃放期间存在明显的空间差异;站点之间小时平均值差异最高达到394 μg/m3。受烟花爆竹燃放的影响,距地面80 m以下颗粒物后向散射强度相近,表明80 m以下颗粒物呈均匀分布。污染事件1是由于烟花爆竹密集燃放引起的,PM2.5主要化学组分为K+、SO₄2-和Cl-,同时SO₂和CO质量浓度显著升高;但EC和OC质量浓度并未明显增加。污染事件2的形成是由于不利的气象条件（逆温、逆湿、下沉气流和较高的相对湿度）促进了SO₂和NO_x在烟花爆竹排放的颗粒物表面发生非均相化学反应,导致SO₄2-和NO₃-浓度快速增加。污染事件3由元宵节烟花爆竹燃放引发,而后呈现二次无机组分与臭氧协同增长的复合型污染特征;此外区域传输对污染事件3也有重要贡献。     

Sensitivity of Climate Changes to CO_2 Emissions in China

In this study, the authors demonstrate that the Coupled Model Intercomparison Project Phase 5 （CMIP5） models project a robust response in changes of mean and climate extremes to warming in China. Under a scenario of a 1% CO2 increase per year, surface temperature in China is projected to increase more rapidly than the global average, and the model ensemble projects more precipitation （2.2%/℃）. Responses in changes of climate extremes are generally much stronger than that of climate means. The majority of models project a consistent re- sponse, with more warm events but fewer cold events in China due to CO2 warming. For example, the ensemble mean indicates a high positive sensitivity for increasing summer days （12.4%/℃） and tropical nights （26.0%/℃）, but a negative sensitivity for decreasing frost days （-4.7%/℃） and ice days （-7.0%/℃）. Further analyses indicate that precipitation in China is likely to become more extreme, featuring a high positive sensitivity. The sensitivity is high （2.4%/℃） for heavy precipitation days （〉 10 mm d l） and increases dramatically （5.3%/℃） for very heavy precipitation days （〉 20 mm d-1）, as well as for precipitation amounts on very wet days （10.8%/℃） and extremely wet days （22.0%/℃）. Thus, it is concluded that the more extreme precipitation events generally show higher sensitivity to CO2 warming. Additionally, southern China is projected to experience an increased risk of drought and flood occurrence, while an increased risk of flood but a decreased risk of drought is likely in other regions of China.     

晋城市冬、春季PM2.5和PM10污染水平时空分布及其与气象因子的关系

为深入了解晋城市颗粒物浓度时空分布特征,对晋城市2017年12月至2018年5月国控点、小型站和微型站PM2.5及PM10小时浓度数据进行收集整理,并进行空间插值分析和时间变化趋势分析及与气象监测数据的相关分析。结果表明:颗粒物浓度在冬、春季节具有明显差异,冬季PM10与PM2.5高值区主要位于东北部及东南小部分区域,春季PM10高值区位于城区南部区域,PM2.5高值区主要集中于城区。晋城市城区和郊区PM10与PM2.5月均浓度整体呈单峰型变化,PM10在4月份最高(157.54±5.67μg·m^-3),PM2.5在1月份最高(94.08±2.25μg·m^-3)。冬季PM2.5/PM10平均为0.57,春季平均为0.45。颗粒物小时浓度的变化呈现单峰单谷的型式,冬季PM10与PM2.5小时平均浓度最高值均出现在10时,春季均出现在09时。监测期间晋城市PM10与PM2.5的小时浓度值与相对湿度有较高的正相关性(p<0.01),与风速、风向有较高的负相关性(p<0.01),与温度和气压的相关性较低。冬季,东北至正南风向时,PM10与PM2.5的浓度普遍高于西北风向时的浓度,对晋城冬、春季国控点颗粒物浓度贡献率最高的风向风速为东南偏南风向,风速在1 m/s以内。     

Unstable Dynamical Properties of Spiral Cloud Bands in Tropical Cyclones

A nondivergent barotropic model （Model 1） and a barotropic primitive equation vortex model （Model 2） are linearized respectively in this paper. Then their perturbation wave spectrums are computed with a normal mode approach to study the instability problem on an appointed tropical cyclone （TC）-like vortex, thereby, the dynamic instability properties of spiral cloud bands of TCs are discussed. The results show that the unstable mode of both models exhibits a spiral band-like structure that propagates away from the vortex outside the radius of maximum winds. The discrete modal instability of the pure vortex Rossby wave can account for the generation of the eyewall and the inner spiral band. The unstable mode in Model 2 has three parts, i.e., eyewall, inner and outer spiral bands. This mode can be interpreted as a mixed vortex Rossby-inertia gravitational wave. The unbalanced property of the wave outside the stagnation radius of the vortex Rossby wave is one of the important reasons for the formation of the outer spiral band in TCs. Accordingly, the outer spiral band can be identified to possess properties of an inertial-gravitational wave. When the formation of unstable inner and outer spiral bands is studied, a barotropic vortex model shall be used. In this model, the most unstable perturbation bears the attributes of either the vortex Rossby wave or the inertial-gravitational wave, depending on the vortex radius. So such perturbations shall be viewed as an unbalanced and unstable mixed wave of these two kinds of waves.