西宁市典型污染日PM10输送规律研究

为研究西宁市PM₁₀的区域性污染特征,对2006年3月至2010年2月各季逐日大气污染指数（API,首要污染物为PM₁₀）进行统计分析。利用后向轨迹模型（HYSPLIT Model）对西宁市典型污染日（API > 200）中气团的后向轨迹进行模拟,研究PM₁₀的运动轨迹和区域性污染的可能来源。结果表明：西宁市一年中春季（集中于3月和4月）PM₁₀污染严重,与该季节气团对颗粒物的长距离输送有关。造成西宁市重污染状况的主要天气是风沙尘,北部和西北部的沙漠地区是主要风沙源;相邻城市PM₁₀污染峰值的提前与滞后,体现出区域性污染的传输过程。     

北京地区PM10污染的气象特征

选用北京城郊5个代表站2000年可吸人颗粒物PM10逐时浓度监测资料,较为系统地统计分析了北京地区主要空气污染物一PM10的时空分布特征,其中包括PM10平均浓度和各等级出现频率的逐月变化、采暖期和非采暖期平均浓度的逐时变化.揭示了各代表站PM10污染年、日变化趋势、采暖期和非采暖期日变化之间的差异,并分析了PM10浓度与地面常规气象要素的相关性.     

合肥市PM10 输送轨迹分类研究

应用聚类分析的方法,对2001—2005年合肥市逐日72 h后向轨迹按季节分类,结合PM10日均浓度观测资料,分析了不同输送轨迹与该地区PM10浓度之间的关系。结果表明:不同方向后向轨迹所对应的PM10平均浓度有明显不同;最高PM10平均浓度对应的后向轨迹在春、秋和冬季都是来自西北方向,它们与季节平均的相对距平分别为44%,20%和31%;夏季为东北方向,与季节平均的相对距平为20%;其次为本地轨迹,各季的相对距平分别为5%,16%,18%和17%。根据分析得出合肥地区6组易于出现高浓度PM10的后向轨迹及对应的天气形势,并简要分析了其特征。气溶胶的远程输送主要发生在自由大气层,区域输送主要发生在边界层内。合肥地区大气污染事件超过50%与远程输送有关。移动快的气团不一定对应低浓度的PM10。     

哈尔滨市PM10污染与气象条件分析

统计分析了2006-2010年哈尔滨市的3种污染物逐日污染物指数API数据,着重统计分析了哈尔滨市主要污染物PM10的逐月和季节演变特征,并对PM10浓度与平均气温、能见度、降水量、相对湿度、气压和平均风速6个气象要素的关系做了初步定量分析。研究结果表明：2006-2010年PM10浓度变化不大,空气质量好于二级的天数...     

2008年奥运会期间北京地区PM10污染天气形势和气象条件特征研究

利用2008年7～9月北京污染监测资料、气象观测资料、韩国气象厅天气图资料及NCEP再分析资料,分析了2008年奥运会期间北京地区空气动力学当量直径小于等于10μm颗粒物(PM10)污染特征及其成因,统计了利于和不利于污染物扩散的天气形势,研究了北京发生PM10污染的典型天气形势和气象条件。结果表明:1)奥运会期间北京共有8天出现PM10污染,包括一次持续污染过程,奥运会赛时和残奥会赛时未出现污染过程,这主要与北京8、9月降水偏多有关;2)不利于污染扩散的天气形势(如风速较小、偏南风、高温高湿、近地层出现持续逆温)出现频率较高,但并未造成特征性的PM10污染,这可能与奥运会期间的污染控制措施有关;3)PM10污染过程多与台风系统或热带低压的北上,从而阻滞了华北地区天气系统的南下东移相关联。     

兰州春季沙尘过程PM10输送路径及其潜在源区

将2001-2008年分为沙尘天气相对多年和相对少年,计算兰州市春季逐日4个时次的4d气团后向轨迹。通过聚类分析得到春季到达兰州市区的主要气团轨迹组,结合可吸入颗粒物PM10日均质量浓度资料,通过计算潜在源贡献因子PSCF（potential source contribution function）和浓度权重轨迹CWT（concentration-weighted trajectory）,得到影响兰州市春季PMlo质量浓度的潜在源区以及不同源区对兰州市春季PM10质量浓度贡献的差异。结果表明,在沙尘天气相对多年,西路径和西北路径发生比例最高,分别占总轨迹的33％和19．4％,其中有50％以上为污染轨迹,是造成兰州市春季高质量浓度PM10污染的主要输送路径。沙尘天气相对少年的主要输送路径是西路径,其次是北路径,分别占23．6％和18％。影响兰州市春季大气PM10质量浓度的潜在源区分布在新疆塔里木盆地、吐鲁番盆地、青海柴达木盆地、甘肃河西走廊、内蒙古中部和西部的沙漠戈壁地区。     

造成北京PM10重污染的二类典型天气形势

利用北京空气质量监测资料和NCEP再分析资料,分析了北京发生PM10重污染的天气形势。研究表明:1)虽然北京地区PM10重污染(API指数3级以上)每年只有10 d左右,但与之关联的轻微或轻度空气污染(API指数3级)天数,却可能占全年3级污染总天数的40%-50%。因此,分析研究造成北京PM10重污染的天气形势,对于空气污染的预警预报以及污染源的控制和管理,都具有十分重要意义。2)通过海平面气压场的主观分析,确定了二类北京PM10重污染的典型天气形势,即高压南下东移阻滞型和与北上台风(或热带低压)相关联的弱高压控制型,并指出了后者在2008年奥运会期间,对开展北京空气污染预报和污染控制的指导作用。     

上海崇明岛PM2.5和PM10污染特征及气象因素影响分析

2015年上海崇明岛PM2.5和 PM10浓度变化特征及气象因素影响分析     

基于无人机垂直观测的南京PM2.5污染个例研究

为了深入理解边界层内气温、相对湿度对PM2.5垂直分布和近地面污染的影响,本文使用搭载了多参数大气环境探测传感器的无人机对南京2017年12月3～4日和12月23～24日的PM2.5浓度、气温和相对湿度进行垂直观测,结合对气象数据的分析及HYSPLIT4（Hybrid Single Particle Lagrangian Integrated Trajectory version 4）轨迹计算模式的应用,对这两次PM2.5的垂直分布特征及污染过程的成因进行了分析。结果表明,PM2.5浓度和相对湿度呈明显的正相关关系,在12月23～24日的6次观测中相关系数均值达到0.96。逆温层下部,PM2.5浓度和相对湿度高且垂直差异较小;逆温层以上,PM2.5浓度和相对湿度随高度升高而迅速降低。由于大气扩散条件较差,导致PM2.5在华北平原南部不断累积,之后受到高压系统的影响分别向南和东南转移。这两次PM2.5污染过程都明显受到外部输送的影响,大气逆温对PM2.5和水汽的向上输送有明显的抑制作用,外部输送和局部逆温是导致这两次PM2.5污染的主要原因。     

郑州市区PM10污染状况及相关气象条件分析

利用郑州市区2003年空气质量日报和同期气象观测资料,分析了郑州市区PM10(>10 μm可吸入颗粒物)污染状况及相关气象条件变化特征,结果表明郑州市区PM10污染全年各月均以2级为主,占总样本数的77.5%;其次是3级污染,占15.1%,1级只占7.4%.1～7月份3级污染逐渐减少,8～11月份1级天气占一定比例.全年3级污染日依自然季节变化逐渐减少.出现≥3级污染日时,空气相对湿度为61%～70%的占3级污染日的1/3;日均风速≤2.0 m/s的日数占3级污染日的78%.     

Monthly Variations of Atmospheric Circulations Associated with Haze Pollution in the Yangtze River Delta and North China

Haze pollution in early winter(December and January) in the Yangtze River Delta(YRD) and in North China(NC)are both severe;however, their monthly variations are significantly different. In this study, the dominant large-scale atmospheric circulations and local meteorological conditions were investigated and compared over the YRD and NC in each month. Results showed that the YRD(NC) is dominated by the so-called Scandinavia(East Atlantic/West Russia)pattern in December, and these circulations weaken in January. The East Asian December and January monsoons over the YRD and NC have negative correlations with the number of haze days. The local descending motion facilitates less removal of haze pollution over the YRD, while the local ascending motion facilitates less removal of haze pollution over NC in January, despite a weaker relationship in December. Additionally, the monthly variations of atmospheric circulations showed that adverse meteorological conditions restrict the vertical(horizontal) dispersion of haze pollution in December(January) over the YRD, while the associated local weather conditions are similar in these two months over NC.     

长江三角洲高影响天气演变特征及成因分析

利用1959 2010年长江三角洲国家基本/基准气象站资料以及大气环流资料和区域土地利用变化资料,分析了长江三角洲高影响天气的变化特征及其对大气环流系统变化和区域城市化、土地利用变化的响应。结果表明,1959 2010年间,长江三角洲低温、雷暴、大风、大雾和降雪日数均显著减少,而高温和暴雨日数的变化趋势在统计上不显著;降雪、大雾、雷暴和低温日数发生了减少突变,而高温和暴雨日数发生了增多突变。在空间上,雷暴和大风日数在整个长江三角洲显著减少,低温日数在北部和中部地区显著减少,降雪日数在东部和南部地区显著减少,高温日数仅在江苏南通、上海、杭州湾地区以及浙江东部显著增加。52年间西太平洋副热带高压和北半球环状模(或北极涛动)增强,而北半球极涡及欧亚经向环流减弱,大气环流系统的综合作用导致长江三角洲大风、低温和降雪日数减少和高温日数增加。区域城市化和土地利用变化也在一定程度上导致长江三角洲高温日数增加和大雾、大风日数减少。     

长江三角洲西部地区PM2.5输送轨迹分类研究

长三角4个省会（直辖市）城市（上海、南京、合肥、杭州）中,合肥与南京的PM_2.5浓度演变有较高的一致性。应用聚类分析的方法对2013-2015年合肥非降水日（日降水量低于10 mm）100 m高度（代表近地层）和1000 m高度（代表边界层中上部）的72 h后向轨迹进行分类,结合合肥2013-2015年PM_2.5日均浓度资料,探讨近地层和边界层中上部输送轨迹与长三角西部PM_2.5浓度的关系。近地层和边界层中上部分别得到7组和6组不同的后向轨迹;不同输送轨迹对应的PM_2.5浓度、重污染（重度以上污染,PM_2.5日均浓度大于150 μg/m³）天数、能见度、地面风速、相对湿度等都有显著不同,尤其是在近地层。100 m高度,平均长度最短、来向偏东的轨迹组对应的PM_2.5浓度均值最高（约是组内均值最低值的2倍）、重污染天数最多,且占比最高（30%）,重污染日对应的气流在过去72 h下降高度均值仅28 m,明显低于其他PM_2.5污染等级日;来向偏西北、长度较短的轨迹组,PM_2.5浓度均值和重污染天数为第2高,这一类轨迹占比14%,气流到达本地前存在明显的下沉运动,反映了远距离输送加剧本地PM_2.5重污染的特征。这两类轨迹常对应PM_2.5日均浓度的上升。PM_2.5平均浓度最低的2个轨迹组分别是来自东北和西南的较长轨迹组,所占比例分别为6.4%和10.3%,这2类轨迹往往对应着PM_2.5日均浓度下降。1000 m高度的结果与100 m高度结果类似,但PM_2.5平均浓度的组间差异不及100 m高度,与2001-2005年PM₁₀浓度与输送轨迹的关系不同。对3 a中84个重污染日两个高度的后向轨迹进行聚类,近地层和边界层中上部各得到7类和6类PM_2.5重污染日的天气形势。近地层92%的重污染日对应的海平面气压形势场上,从华北到华东属于均压区,气压梯度小,轨迹来向以偏东到偏北方向为主,垂直方向延伸高度在950 hPa以下。1000 m高度,77%的重污染日属于相对较短的轨迹组,对应的850 hPa高度场特征为从中国西北（新疆）到东南受高压控制,长三角或位于高压底部,或位于两高压之间的均压区。这对PM_2.5浓度预报有较好的指示意义。     

Seasonal Variation of Columnar Aerosol Optical Properties in Yangtze River Delta in China

In order to understand the seasonal variation of aerosol optical properties in the Yangtze River Delta,5 years of measurements were conducted during September 2005 to December 2009 at Taihu,China.The monthly averages of aerosol optical depth were commonly >0.6;the maximum seasonal average(0.93) occurred in summer.The magnitude of the Angstr¨om exponent was found to be high throughout the year;the highest values occurred in autumn(1.33) and were the lowest in spring(1.08).The fine modes of volume size distribution showed the maxima(peaks) at a radius of ～0.15 μm in spring,autumn,and winter;at a radius of ～0.22 μm in summer.The coarse modes showed the maxima(peaks) at a radius of 2.9 μm in spring,summer,and autumn and at a radius of 3.8 μm in winter.The averages of single-scattering albedo were 0.92(spring),0.92(summer),0.91(autumn),and 0.88(winter).The averages of asymmetry factor were found to be larger in summer than during other seasons;they were taken as 0.66 at 440-1020 nm over Taihu.The real part of the refractive index showed a weak seasonal variation,with averages of 1.48(spring),1.43(summer),1.45(autumn),and 1.48(winter).The imaginary parts of the refractive index were higher in winter(0.013) than in spring(0.0076),summer(0.0092),and autumn(0.0091),indicating that the atmosphere in the winter had higher absorbtivity.     

Spatiotemporal Variations of Cloud Amount over the Yangtze River Delta, China

Based on the NOAA's Advanced Very High Resolution Radiometer(AVHRR) Pathfinder Atmospheres Extended(PATMOS-x) monthly mean cloud amount data, variations of annual and seasonal mean cloud amount over the Yangtze River Delta(YRD), China were examined for the period 1982–2006 by using a linear regression analysis. Both total and high-level cloud amounts peak in June and reach minimum in December, mid-level clouds have a peak during winter months and reach a minimum in summer, and lowlevel clouds vary weakly throughout the year with a weak maximum from August to October. For the annual mean cloud amount, a slightly decreasing tendency(–0.6% sky cover per decade) of total cloud amount is observed during the studying period, which is mainly due to the reduction of annual mean high-level cloud amount(–2.2% sky cover per decade). Mid-level clouds occur least(approximately 15% sky cover) and remain invariant, while the low-level cloud amount shows a significant increase during spring(1.5% sky cover per decade) and summer(3.0% sky cover per decade). Further analysis has revealed that the increased low-level clouds during the summer season are mainly impacted by the local environment. For example,compared to the low-level cloud amounts over the adjacent rural areas(e.g., cropland, large water body, and mountain areas covered by forest), those over and around urban agglomerations rise more dramatically.     

Impact of Taihu Lake on City Ozone in the Yangtze River Delta

The lake-breeze at Taihu Lake generates a different specific heat capacity between the water body and the surrounding land. Taihu Lake has a significant impact on the atmospheric conditions and the air quality in the Yangtze River Delta. This phenomenon is referred to as the Taihu Lake effect. In this study, two simulations were conducted to determine the impact of the Taihu Lake effect in the reference experiment(R-E) and sensitivity experiments(NO TH). The control simulations demonstrated that the meteorological field and the spatial distribution of ozone(O3) concentrations over Taihu lake obviously changed once the land-use type of water body was substituted by cropland. The surface temperature of Taihu Lake was reduced under the impact of Taihu Lake, and a huge temperature difference caused a strong lake-breeze effect. The results also showed that the difference in the average concentrations of O3 between the R-E and NO TH experiments reached 12 ppbv in most areas of Taihu Lake, all day, on 20 May 2014. During daytime(0800–1600 LST, LST=UTC+8), the influence of the Taihu Lake effect on O3 in the Suzhou region was not significant. However, the influence of the Taihu Lake effect on O3 in the Suzhou region was obvious during nighttime(1800–2400 LST). The larger changes in the physical and chemical processes were horizontal and vertical advections under the influence of the Taihu Lake effect in Taihu Lake.     

Particulate Amines in the Background Atmosphere of the Yangtze River Delta,China: Concentration,Size Distribution,and Sources

Amines are important for new particle formation and subsequent growth in the atmosphere. Consequently, the processes involved are receiving more attention in recent years. Here, we conduct a field observation in order to investigate the atmospheric particulate amines at a background site in the Yangtze River Delta(YRD) during the summer of 2018.Four amines in PM_(2.5), i.e., methylamine(MA), dimethylamine(DMA), diethylamine(DEA), and trimethylamine(TMA),were collected, twice daily and analyzed. During the campaign, our measurements found the concentrations of MA, DMA,DEA, and TMA of 15.0 ± 15.0, 6.3 ± 6.9, 20.4 ± 30.1, and 4.0 ± 5.9 ng m–3, respectively, and the four amines correlated well with each other. The concentration of amines appear to be independent of whether they were collected during the day or night. Both MA and DMA exhibited a bimodal size distribution that had peaks at 0.67 and 1.1 μm, suggesting amines preferably distribute on submicron particles. Boundary layer height(BLH), relative humidity, and pH of aerosols were found have a negative relationship with amines, while aerosol liquid water content(ALWC) was found to have a positive relationship with amines. The PMF(positive matrix factorization) source apportionment results showed that the main source of amines in Chongming Island was of anthropogenic origin such as industrial and biomass emission, followed by marine sources including sea salt and marine biogenic sources. Given that the YRD region is still suffering from complex atmospheric pollution and that the knowledge on aerosol amines is still limited, more field studies are in urgent need for a better understanding of the pollution characteristics of amines.     

Impacts of Weather Conditions Modified by Urban Expansion on Surface Ozone： Comparison between the Pearl River Delta and Yangtze River Delta Regions

In this paper, the online weather research and forecasting and chemistry (WRF-Chem) model is used to explore the impacts of urban expansion on regional weather conditions and its implication on surface ozone concentrations over the Pearl River Delta(PRD) and Yangtze River Delta(YRD) regions. Two scenarios of urban maps are used in the WRF-Chem to represent the early 1990s (pre-urbanization) and the current urban distribution in the PRD and the YRD. Month-long simulation results using the above land-use scenarios for March 2001 show that urbanization increases both the day- and night-time 2-m temperatures by about 0.6^oC and 1.4^oC, respectively. Daytime reduction in the wind speed by about 3.0 m s^-1 is larger than that for the nighttime (0.5 to 2 m s^-1). The daytime increase in the PBL height (> 200 m) is also larger than the nighttime (50--100 m). The meteorological conditions modified by urbanization lead to detectable ozone-concentration changes in the PRD and the YRD. Urbanization increases the nighttime surface-ozone concentrations by about 4.7%--8.5% and by about 2.9%--4.2% for the daytime. In addition to modifying individual meteorological variables, urbanization also enhances the convergence zones, especially in the PRD. More importantly, urbanization has different effects on the surface ozone for the PRD and the YRD, presumably due to their urbanization characteristics and geographical locations. Even though the PRD has a smaller increase in the surface temperature than the YRD, it has (a) weaker surface wind speed, (b) smaller increase in PBL heights, and (c) stronger convergence zones. The latter three factors outweighed the temperature increase and resulted in a larger ozone enhancement in the PRD than the YRD.     

中国长三角地区PM2.5时空分布数值模拟研究

利用第三代空气质量预报模式LOTOS-EUROS(Long Term Ozone Simulation-European Operational Smog)对2018年中国长三角地区细颗粒物(PM2.5)浓度的时空分布进行数值模拟,通过对比模拟结果与地面观测值,验证模式对PM2.5长期特征模拟的合理性并探讨长三角地区P...     

Estimate of Hydrofluorocarbon Emissions for 2012–16 in the Yangtze River Delta,China

Hydrofluorocarbons(HFCs) have been widely used in China as substitutes for ozone-depleting substances,the production and use of which are being phased out under the Montreal Protocol.China is a major consumer of HFCs around the world,with its HFC emissions in CO_2-equivalent contributing to about 18% of the global emissions for the period2012-16.Three methods are widely used to estimate the emissions of HFCs-namely,the bottom-up method,top-down method and tracer ratio method.In this study,the tracer ratio method was adopted to estimate HFC emissions in the Yangtze River Delta(YRD),using CO as a tracer.The YRD region might make a significant contribution to Chinese totals owing to its rapid economic growth.Weekly flask measurements for ten HFCs(HFC-23,HFC-32,HFC-125,HFC-134 a,HFC-143 a,HFC-152 a,HFC-227 ea,HFC-236 fa,HFC-245 fa and HFC-365 mfc) were conducted at Lin'an Regional Background Station in the YRD over the period 2012-16,and the HFC emissions were 2.4±1.4 Gg yr~(-1) for HFC-23,2.8±1.2 Gg yr~(-1) for HFC-32,2.2±1.2 Gg yr~(-1) for HFC-125,4.8±4.8 Gg yr~(-1) for HFC-134 a,0.9±0.6 Gg yr~(-1) for HFC-152 a,0.3±0.3 Gg yr~(-1) for HFC-227 ea and 0.3±0.2 Gg yr~(-1) for HFC-245 fa.The YRD total HFC emissions reached 53 Gg CO_2-e yr~(-1),contributing 34% of the national total.The per capita HFC CO_2-equivalent emissions rate was 240 kg yr-1,while the values of per unit area emissions and per million GDP emissions reached 150 Mg km~(-2)yr~(-1) and 3500 kg yr~(-1)(million CNY GDP)-1,which were much higher than national or global levels.