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1.
北京大气能见度的主要影响因子   总被引：4，自引：3，他引：1       下载免费PDF全文
利用北京市道面自动气象站、国家级自动气象站等多种观测数据分析北京地区2007—2015年能见度及其主要影响因子, 并挑选两次典型低能见度事件过程进行详细分析。从空间分布看, 北京西北地区能见度明显高于中心城区和东南大部地区。从时间分布看, 北京地区平均能见度最大值出现在5月, 最小值出现在7月; 日间的最低值多出现在06:00(北京时, 下同)左右, 冬季略向后推迟; 最高值多出现在16:00前后, 冬季略有提前。整体而言, 2007—2015年北京地区发生低能见度事件的概率为62.14%, 且发生低能见度的事件集中于1~5 km, 霾事件中干霾、湿霾的发生频率分别为86.13%和13.87%。能见度的主要影响因子为相对湿度、风速和PM2.5浓度。其中, 能见度与风速呈正相关, 与相对湿度和PM2.5浓度呈反相关。需要指出的是, 当相对湿度增加至80%, 能见度受PM2.5浓度的影响程度在下降, 而主要受相对湿度的影响。基于所选个例, 当北京地区出现湿霾事件时, 能见度的恶化程度远高于干霾事件, 且PM2.5浓度需比干霾事件时下降得更低才能有效改善能见度。  相似文献   

2.
气候变化引起的地面气溶胶浓度变化与区域空气质量密切相关。本文利用“国际大气化学—气候模式比较计划”（Atmospheric Chemistry and Climate Model Intercomparison Project, ACCMIP）中4个模式的试验数据分析了RCP8.5情景下2000~2100年气候变化对中国气溶胶浓度的影响。结果显示,在人为气溶胶排放固定在2000年、仅考虑气候变化的影响时,2000~2100年气候变化导致中国北部地区（31°N~45°N, 105°E~122°E）硫酸盐、有机碳和黑碳气溶胶分别增加28%、21%和9%,硝酸盐气溶胶在中国东部地区减少30%。气候变化对细颗粒物（PM2.5）浓度的影响有显著的季节变化特征,冬季PM2.5浓度在中国东部减少15%,这主要是由硝酸盐气溶胶在冬季的显著减少造成的;夏季PM2.5浓度在中国北部地区增加16%,而长江以南地区减少为9%,这可能与模式模拟的未来东亚夏季风环流的增强有关。  相似文献   

3.
针对2013年1月江苏淮安地区发生的一次连续性雾霾天气过程,分析该天气过程中PM10和PM2.5的质量浓度演变特征、能见度与气象要素之间的关系、中低层环流特征以及污染物来源。结果表明:雾霾期间PM10和PM2.5质量浓度最低值出现在05:00至07:00(北京时间,下同)和13:00至17:00,最高值出现在21:00至23:00,PM10和PM2.5质量浓度并非同时达到极大值;持续变化较小的气压梯度、较低的风速、相对湿度的增大以及PM2.5和PM10质量浓度的增高是雾霾发生发展的必要条件;能见度与气压、相对湿度、PM2.5质量浓度的相关性较好,建立回归方程,对能见度的整体变化趋势拟合效果较好;高空环流形势平稳、中低层的暖平流、持续稳定少动的地面高压场分布为雾霾天气的持续发生发展提供了有利的形势背景;稳定的层结结构、中低层偏东及偏东北方向气团的输送、本地污染源以及严重的空气污染是此次过程中能见度偏低、霾天数较多的主要原因。  相似文献   

4.
The chemical composition of PM10 and PM2.5 samples collected during two seasonal monitoring campaigns at residential, urban and industrial Apulia Region- sites was investigated. Ionic fraction, carbonaceous compounds and Polycyclic Aromatic Hydrocarbons were determined for all samples. High correlations among PM data collected in the investigated sites suggested the regional character of particulate matter. It was also confirmed by five days back trajectories analysis. Moreover, no significant seasonal trend in PM mass concentration was observed in the investigated sites. These results, relevant for the area under investigations, were not observed in the North of Italy and Europe and allow to conclude that PM10 and PM2.5 cannot be considered ‘good’ indicators for the evaluation of local anthropic contributions to air quality. On the contrary, the high levels of Polycyclic Aromatic Hydrocarbons found in Taranto sampling sites suggested that PAHs can be a better indicator for this purpose. This result is also relevant in order to weigh the importance of industrial area and to suggest right policy control to decision makers.  相似文献   

5.
Haze-fog conditions over northern India are associated with visibility degradation and severe attenuation of solar radiation by airborne particles with various chemical compositions. PM2.5 samples have been collected in Delhi, India from December 2011 to November 2012 and analyzed for carbonaceous and inorganic species. PM10 measurements were made simultaneously such that PM10–2.5 could be estimated by difference. This study analyzes the temporal variation of PM2.5 and carbonaceous particles (CP), focusing on identification of the primary and secondary aerosol emissions, estimations of light extinction coefficient (bext) and the contributions by the major PM2.5 chemical components. The annual mean concentrations of PM2.5, organic carbon (OC), elemental carbon (EC) and PM10–2.5 were found to be 153.6 ± 59.8, 33.5 ± 15.9, 6.9 ± 3.9 and 91.1 ± 99.9 μg m?3, respectively. Total CP, secondary organic aerosols and major anions (e.g., SO4 2? and NO3 ?) maximize during the post-monsoon and winter due to fossil fuel combustion and biomass burning. PM10–2.5 is more abundant during the pre-monsoon and post-monsoon. The OC/EC varies from 2.45 to 9.26 (mean of 5.18 ± 1.47), indicating the influence of multiple combustion sources. The bext exhibits highest values (910 ± 280 and 1221 ± 371 Mm?1) in post-monsoon and winter and lowest in monsoon (363 ± 110 and 457 ± 133 Mm?1) as estimated via the original and revised IMPROVE algorithms, respectively. Organic matter (OM =1.6 × OC) accounts for ~39 % and ~48 % of the bext, followed by (NH4)2SO4 (~21 % and ~24 %) and EC (~13 % and ~10 %), according to the original and revised algorithms, respectively. The bext estimates via the two IMPROVE versions are highly correlated (R2 = 0.95, root mean square error = 38 % and mean bias error = 28 %) and are strongly related to visibility impairment (r = ?0.72), mostly associated with anthropogenic rather than natural PM contributions. Therefore, reduction of CP and precursor gas emissions represents an urgent opportunity for air quality improvement across Delhi.  相似文献   

6.
Summary In the first part of this study, intensive measurements of particulate matter and trace gaseous were made to assess the characteristics of air pollutants in 14 sites covering most of Egypt, and to present a clear picture about the relationship of air pollutants with meteorology. The goal of this study is to examine the effect of weather conditions and air pollutants on the receipt of solar radiation during cloudless days at five sites. The results have shown, that the relative attenuation of the total solar radiation varied dramatically from 22% in winter to about 9.3% in summer. This finding may be attributed to PM10 and CO effects, which are in the highest level during winter.  相似文献   

7.
Climate change modulates surface concentrations of fine particulate matter (PM2.5) and ozone (O3), indirectly affecting premature mortality attributed to air pollution. We estimate the change in global premature mortality and years of life lost (YLL) associated with changes in surface O3 and PM2.5 over the 21st century as a result of climate change. We use a global coupled chemistry-climate model to simulate current and future climate and the effect of changing climate on air quality. Epidemiological concentration-response relationships are applied to estimate resulting changes in premature mortality and YLL. The effect of climate change on air quality is isolated by holding emissions of air pollutants constant while allowing climate to evolve over the 21st century according to a moderate projection of greenhouse gas emissions (A1B scenario). Resulting changes in 21st century climate alone lead to an increase in simulated PM2.5 concentrations globally, and to higher (lower) O3 concentrations over populated (remote) regions. Global annual premature mortality associated with chronic exposure to PM2.5 increases by approximately 100 thousand deaths (95 % confidence interval, CI, of 66–130 thousand) with corresponding YLL increasing by nearly 900 thousand (95 % CI, 576–1,128 thousand) years. The annual premature mortality due to respiratory disease associated with chronic O3 exposure increases by +6,300 deaths (95 % CI, 1,600–10,400). This climate penalty indicates that stronger emission controls will be needed in the future to meet current air quality standards and to avoid higher health risks associated with climate change induced worsening of air quality over populated regions.  相似文献   

8.
南京大气能见度变化规律及影响因子分析   总被引：7，自引：1，他引：6       下载免费PDF全文
利用累积百分率法、Ridit中值分析法、"非常好"能见度出现频率法以及平均能见度年际和季节变化法,对1980—2005年南京大气能见度年际变化趋势进行分析,发现1980—1984年能见度呈上升趋势,1985年以后则在波动中呈明显下降趋势。26 a中,日均大气能见度最小值为0.55 km,最大值为29.25 km,平均值为8.59 km。大气能见度具有明显的日变化和季节变化特征,一日之中,14时最好,08时最差;一年之中,冬季能见度最低,夏季最高。能见度与相对湿度呈负相关,与风速呈正相关,与温度和气压的相关性相对较小。PM10是影响南京地区大气能见度的首要污染物,通过对能见度与PM10平均质量浓度进行曲线拟合发现,二者呈负相关,复相关系数在秋季最高,夏季最低。由统计预报方程可知,空气污染和气象条件协同作用对能见度的影响在春季、秋季、冬季较为明显,夏季则相对较差。  相似文献   

9.
《Atmospheric Research》2007,83(3-4):663-679
The objective of this study was to investigate the correlation of visibility with chemical composition of Kaohsiung aerosols. Daytime visibility was observed around noon at two observation sites in metropolitan Kaohsiung, Taiwan in the years of 1999 and 2000. Both seasonal and diurnal variation patterns of visibility were observed in the region. Ambient aerosols were sampled and analyzed for 11 constituents, including water-soluble ionic species (Cl−, NO3−, SO4−2, NH4+, K+, Na+, Ca+2, and Mg+2) and carbonaceous contents (OC, EC, and TC), to characterize the chemical composition of Kaohsiung aerosols. Furthermore, a stepwise multiple linear regression model was developed to elucidate the influence of aerosol species on visibility impairments. The results showed that sulfate was the dominant species that affected both light scattering coefficient and visibility. On average, the percentage contributions of visibility degrading species to light scattering coefficient were 29% for sulfate, 28% for nitrate, 22% for total carbon, and 21% for PM2.5-remainder. An empirical regression model of visibility based on sulfate, nitrate, and relative humidity was also developed. The model showed that sulfate in PM2.5 was the most sensitive species to visibility variation, suggesting that the reduction of sulfate in PM2.5 could effectively improve the visibility of metropolitan Kaohsiung. During the investigation period, an event of Asian dusts intruded metropolitan Kaohsiung and dramatically increased the aerosol loadings, especially in the coarse particles. However, local visual air quality did not degrade accordingly during the Asian dust event because both visibility and light scattering coefficient are affected mainly by the fine particles. The results are discussed in detail in the paper.  相似文献   

10.
利用无人机搭载气象及环境监测设备于2020年7月29—31日在太原进行飞行试验,对不同高度层颗粒物和气象要素进行观测,得到PM_(2.5)三维分布及其随时间的变化特征,并通过气象要素、天气形势和后向轨迹分析得到污染累积和消散成因以及外地传输作用影响。结果表明:PM_(2.5)浓度的垂直分布差异显著,下午大部分时次满足"下高上低"规律,上午边界层垂直混合和颗粒物吸湿增长可能导致"下低上高"的情况;逆温层对大气垂直混合有明显抑制作用;29日为污染物积累过程,30日和31日白天均为消散过程;副热带高压带来的小风、高湿环境是29日颗粒物逐渐累积的原因,30日槽前对流发展和较大的风速有利于颗粒物浓度下降,31日相对湿度较低、对流发展旺盛使PM_(2.5)浓度快速下降;试验期间气流主要来自东南方向,太原市PM_(2.5)本地积累占主导地位,外地传输更多来自于本省晋中、长治等邻近城市。  相似文献   

11.
Air circulation due to the urban heat island (UHI) effect can influence the dispersion of air pollutants in a metropolis. This study focusses on the influence of the UHI effect on particulate matter (PM; including PM2.5 and PM2.5–10) between May and September 2010–2012 in the Taipei basin. Meteorological and PM data were obtained from the sites, owned by the governmental authorities. The analysis was carried out using t test, relative indices (RIs), Pearson product–moment correlation and stepwise regression. The results show that the RI values for PM were the highest at moderate UHI intensity (MUI; 2 °C ≤ UHI < 4 °C) rather than at strong UHI intensity (SUI; 4 °C ≤ UHI) during the peak time for anthropogenic emissions (20:00 LST). Neither the accumulation of PM nor the surface convergence occurred in the hot centre, as shown by the case study. At MUI, more than 89 % of the synoptic weather patterns showed that the weather was clear and hot or that the atmosphere was stable. The variation in PM was associated with horizontal and vertical air dispersion. Poor horizontal air dispersion, with subsidence, caused an increase in PM at MUI. However, the updraft motion diluted the PM at SUI. The stepwise regression models show that the cloud index and surface air pressure determined the variation in PM2.5–10, while cloud index, wind speed and mixing height influenced the variation in PM2.5. In conclusion, a direct relationship between UHI effect and PM was not obvious.  相似文献   

12.
南京北郊2011年春季气溶胶粒子的散射特征   总被引：3，自引：2，他引：1       下载免费PDF全文
利用南京北郊2011年春季积分浊度仪的观测资料,结合PM2.5质量浓度、能见度和常规气象资料,分析了南京北郊春季气溶胶散射系数的变化特征、散射系数与PM2.5质量浓度和能见度的关系。结果表明,观测期间气溶胶散射系数平均值为311.5±173.3 Mm-1,小时平均值出现频率最高的区间为100~200 Mm-1;散射系数的日变化特征明显,总体为早晚大,中午及午后小。散射系数与PM2.5质量浓度的变化趋势基本一致,但与能见度呈负相关关系。霾天气期间散射系数日平均值为700.5±341.4 Mm-1,最高值达到近1 900 Mm-1;结合地面观测资料、NCEP/NCAR再分析资料和后向轨迹模式分析显示,霾期间气块主要来自南京南部和东南方向。  相似文献   

13.
The objective of this study was to investigate the correlation of visibility with chemical composition of Kaohsiung aerosols. Daytime visibility was observed around noon at two observation sites in metropolitan Kaohsiung, Taiwan in the years of 1999 and 2000. Both seasonal and diurnal variation patterns of visibility were observed in the region. Ambient aerosols were sampled and analyzed for 11 constituents, including water-soluble ionic species (Cl−, NO3−, SO4−2, NH4+, K+, Na+, Ca+2, and Mg+2) and carbonaceous contents (OC, EC, and TC), to characterize the chemical composition of Kaohsiung aerosols. Furthermore, a stepwise multiple linear regression model was developed to elucidate the influence of aerosol species on visibility impairments. The results showed that sulfate was the dominant species that affected both light scattering coefficient and visibility. On average, the percentage contributions of visibility degrading species to light scattering coefficient were 29% for sulfate, 28% for nitrate, 22% for total carbon, and 21% for PM2.5-remainder. An empirical regression model of visibility based on sulfate, nitrate, and relative humidity was also developed. The model showed that sulfate in PM2.5 was the most sensitive species to visibility variation, suggesting that the reduction of sulfate in PM2.5 could effectively improve the visibility of metropolitan Kaohsiung. During the investigation period, an event of Asian dusts intruded metropolitan Kaohsiung and dramatically increased the aerosol loadings, especially in the coarse particles. However, local visual air quality did not degrade accordingly during the Asian dust event because both visibility and light scattering coefficient are affected mainly by the fine particles. The results are discussed in detail in the paper.  相似文献   

14.
The size-segregated chemical composition of aerosol particles was investigated during 1?year at the puy de D?me (1,465?m?a.s.l.), France. These measurements aimed to a better understanding of the influence of the air mass origin on the size-segregated chemical composition of the aerosol at an altitude site. Mountain site measurements are important because they are representative of long range transport and useful for model validation. PM1 mass concentration exhibits a seasonal variability with a summer maximum. The composition of PM1 did not change significantly in terms of relative contribution of water soluble inorganic ions but is rather variable in term of total mass concentrations. For the PM10-1, a different seasonal behaviour was found with maxima concentrations in autumn-winter. Aerosols were classified into four different categories according to their air mass origin: marine, marine modified, continental and Mediterranean. The PM10 aerosol mass at 50?% relative humidity was close to 2.5???g?m?3 in the marine, 4.3???g?m?3 in the marine modified, 10.3???g?m?3 in the continental and 7.7???g?m?3 in the Mediterranean sectors. We noted that the influence of the air mass origin (on the chemical properties) could be seen especially on the PM10-1. A significant PM10-1 mode was found in marine, modified marine, and Mediterranean air masses, and PM1 dominated in the continental air masses samples. As a result, the aerosol chemical composition variability at the puy de D?me is a function of both the season and air mass type and we provide a chemical composition of the aerosol as a function of each of these environmental factors.  相似文献   

15.
大气污染物排放清单是空气质量模拟和空气污染治理的重要依据.本研究比较分析了两套覆盖江苏省的2017年大气污染物排放清单，即分别由上海市环境科学研究院、江苏省环境科学研究院编制的"长三角清单"和"江苏省清单"，并结合区域空气质量模型CMAQ评估不同清单对长三角地区2017年1、4、7、10月的空气质量模拟的影响.清单比较结果表明，除二氧化硫（SO2）以外，江苏省清单估算的各污染物排放量较长三角清单低.通过与观测数据比较，发现两套清单对SO2、氮氧化物（NOx）、臭氧（O3）和细颗粒物（PM2.5）的模型模拟性能均较好.江苏省清单与长三角清单两者的模拟结果空间分布接近，其中江苏省清单模拟的PM2.5和O3在长三角多数地区略低于长三角清单的模拟结果（1月O3除外）.江苏省清单与长三角清单均能够用于空气质量模式模拟，可为江苏地区的细颗粒物和光化学烟雾污染的控制策略制定提供参考.  相似文献   

16.
This work attempts to characterize metallic elements associated with atmospheric particulate matter on a dry deposition plate, a TE-PUF high-volume air sampler and a universal air sampler. Dry deposition fluxes of particulates and concentrations of total suspended particulate, fine (PM2.5) and coarse (PM2.5–10) particulate matters were collected at Taichung harbor sampling sites from August 2004 to January 2005. Chemical analyses of metallic elements were made using a flame atomic absorption spectrophotometer coupled with hollow cathode lamps. Concentrations of metal elements in the forms of coarse particles and fine particles as well as the coarse/fine particulate ratios were presented. Statistical methods such as correlation analysis, principal component analysis and enrichment factor analysis were performed to compare the chemical components and identify possible emission sources at the sampling sites. Metallic elements of Cu, Zn, Pb, Cr, Ni and Mg had higher EFcrust ratios in winter and spring than in summer and autumn. Diurnal and nocturnal variations of metallic element concentrations in fine and coarse particles were also discussed.  相似文献   

17.
Surface ozone (O3) and fine particulate matter (PM2.5) are dominant air pollutants in China. Concentrations of these pollutants can show significant differences between urban and nonurban areas. However, such contrast has never been explored on the country level. This study investigates the spatiotemporal characteristics of urban-to-suburban and urban-to-background difference for O3 (Δ[O3]) and PM2.5 (Δ[PM2.5]) concentrations in China using monitoring data from 1171 urban, 110 suburban, and 15 background sites built by the China National Environmental Monitoring Center (CNEMC). On the annual mean basis, the urban-to-suburban Δ[O3] is ?3.7 ppbv in Beijing–Tianjin–Hebei, 1.0 ppbv in the Yangtze River Delta, ?3.5 ppbv in the Pearl River Delta, and ?3.8 ppbv in the Sichuan Basin. On the contrary, the urban-to-suburban Δ[PM2.5] is 15.8, ?0.3, 3.5 and 2.4 μg m?3 in those areas, respectively. The urban-to-suburban contrast is more significant in winter for both Δ[O3] and Δ[PM2.5]. In eastern China, urban-to-background differences are also moderate during summer, with ?5.1 to 6.8 ppbv for Δ[O3] and ?0.1 to 22.5 μg m?3 for Δ[PM2.5]. However, such contrasts are much larger in winter, with ?22.2 to 5.5 ppbv for Δ[O3] and 3.1 to 82.3 μg m?3 for Δ[PM2.5]. Since the urban region accounts for only 2% of the whole country’s area, the urban-dominant air quality data from the CNEMC network may overestimate winter [PM2.5] but underestimate winter [O3] over the vast domain of China. The study suggests that the CNEMC monitoring data should be used with caution for evaluating chemical models and assessing ecosystem health, which require more data outside urban areas.  相似文献   

18.
北京地区一次重污染天气气溶胶分布与传输特征研究   总被引：8，自引：0，他引：8  
针对北京地区2004年10月26～31日的一次典型重污染天气个例,分析了此次污染过程产生的天气背景和污染物对近地层接收太阳总辐射的削减作用,同时应用MODIS卫星遥感气溶胶产品和地面风场的分布分析了大气污染物的分布和输送特征。结果表明,此次污染过程与大尺度的天气背景有密切关系,地面气压减小和偏南气流导致了此次污染过程;通过比较中国科学院大气物理研究所325m铁塔观测到的2m和280m高度处太阳总辐射可知,在空气质量较好天气,地面以上2～280m大气能够减少太阳总辐射的15%;而在重污染天气时,地面以上2～280m大气能够使太阳总辐射减少20%以上,低层大气显著地影响城市区域下垫面和大气之间的辐射交换;分析MODIS气溶胶分布和地面风场可知,此次污染过程可能是局地污染物积累和外界污染输送造成的。  相似文献   

19.
To investigate the interannual variations of particulate matter (PM) pollution in winter, this paper examines the pollution characteristics of PM with aerodynamic diameters of less than 2.5 and 10 μm (i.e., PM2.5 and PM10), and their relationship to meteorological conditions over the Beijing municipality, Tianjin municipality, and Hebei Province—an area called Jing–Jin–Ji (JJJ, hereinafter)—in December 2013–16. The meteorological conditions during this period are also analyzed. The regional average concentrations of PM2.5 (PM10) over the JJJ area during this period were 148.6 (236.4), 100.1 (166.4), 140.5 (204.5), and 141.7 (203.1) μg m–3, respectively. The high occurrence frequencies of cold air outbreaks, a strong Siberian high, high wind speeds and boundary layer height, and low temperature and relative humidity, were direct meteorological causes of the low PM concentration in December 2014. A combined analysis of PM pollution and meteorological conditions implied that control measures have resulted in an effective improvement in air quality. Using the same emissions inventory in December 2013–16, a modeling analysis showed emissions of PM2.5 to decrease by 12.7%, 8.6%, and 8.3% in December 2014, 2015, and 2016, respectively, each compared with the previous year, over the JJJ area.  相似文献   

20.
China national air quality monitoring network has become the core data source for air quality assessment and management in China. However, during network construction, the significant change in numbers of monitoring sites with time is easily ignored, which brings uncertainty to air quality assessments. This study aims to analyze the impact of change in numbers of stations on national and regional air quality assessments in China during 2013–18. The results indicate that the change in numbers of stations has different impacts on fine particulate matter (PM2.5) and ozone concentration assessments. The increasing number of sites makes the estimated national and regional PM2.5 concentration slightly lower by 0.6?2.2 μg m?3 and 1.4?6.0 μg m?3 respectively from 2013 to 2018. The main reason is that over time, the monitoring network expands from the urban centers to the suburban areas with low population densities and pollutant emissions. For ozone, the increasing number of stations affects the long-term trends of the estimated concentration, especially the national trends, which changed from a slight upward trend to a downward trend in 2014?15. Besides, the impact of the increasing number of sites on ozone assessment exhibits a seasonal difference at the 0.05 significance level in that the added sites make the estimated concentration higher in winter and lower in summer. These results suggest that the change in numbers of monitoring sites is an important uncertainty factor in national and regional air quality assessments, that needs to be considered in long-term concentration assessment, trend analysis, and trend driving force analysis.  相似文献   

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