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1.
武汉作为中部地区高湿度代表城市,大气污染严重,霾天气多发,但有关该地区大气能见度与PM2.5浓度及相对湿度(RH)的定量关系尚不明确。利用2014年9月—2015年3月武汉地区逐时能见度、相对湿度及颗粒物质量浓度观测数据,研究分析了武汉大气能见度与PM2.5浓度及相对湿度的关系,并进行能见度非线性预报初探,得到以下结论:武汉霾时数发生比例高,霾的发生和加重是能见度降低的主要原因;能见度降低伴随大量细粒子产生和累积,这是武汉大气能见度恶化的重要诱因。细颗粒物浓度与相对湿度共同影响和制约大气能见度变化,高湿高浓度时能见度显著下降,湿情景下(RH≥40%),能见度恶化主要是由湿度增高诱使细颗粒物粒径吸湿增长导致其散射效率增大造成的。当RH >90%时,能见度随湿度升高成线性递减,相对湿度每升高1%,武汉平均能见度降低0.568 km。而干情景下(RH<40%),能见度迅速降低的关键因素是PM2.5质量浓度升高。在城市大气细粒子污染背景下,能见度与相对湿度成非线性关系,这主要与PM2.5对能见度的影响及吸湿性颗粒物的散射效率变化有关。PM2.5浓度与能见度成幂函数非线性关系,80%≤RH<90%湿度区段下相关性最强。PM2.5浓度对能见度的影响敏感阈值是随着湿度升高而减小的,干情景下能见度10 km对应的PM2.5浓度阈值为70 μg/m3,湿情景下该阈值为18—55 μg/m3。当PM2.5质量浓度低于约40 μg/m3时,继续降低PM2.5可显著提高武汉大气能见度。预报试验表明,基于神经网络方法建立大气能见度非线性预报模型是可行的,预报能见度相关系数为0.86,均方根误差为1.9 km,能见度≤10 km的TS评分为0.92。网络模型具有较高预报性能,对霾的判别有较高准确性,为衔接区域环境气象数值预报模式,建立大气能见度精细化动力统计模型提供参考依据。  相似文献   

2.
对2017年11月1日—2018年1月31日与2018年11月1日—2019年1月31日连续两年青岛市大气PM1进行监测,获取了PM1中含碳组分的变化趋势,结合国控站点监测数据和气象条件,分析了秋冬季PM1来源.结果表明:2017、2018年秋冬季观测期间PM1日均质量浓度分别为40.58±25.98、42.55±25.05 μg/m3;霾日质量浓度分别为84.71±16.70、81.52±18.39 μg/m3.与2017年相比,2018年同期PM1质量浓度增长4.85%,霾日下降3.76%.2017年霾日PM1中OC、EC质量浓度分别为13.67±3.95、3.95±1.02 μg/m3,2018年分别为16.48±6.34、3.34±1.16 μg/m3.与2017年相比,2018年霾日OC质量浓度增长20.56%,EC下降15.44%.2017、2018年霾日SOC质量浓度分别是非霾日的1.28和2.15倍,表明霾污染发生时易发生有机碳二次转化.含碳组分主成分分析均解析出3个因子.因子1解释变量均最大,分别为58.98%、67.14%,其表征含碳组分主要源于生物质燃烧、燃煤、道路扬尘及汽油车尾气等排放源.由后向气流轨迹分析得出,2017、2018年秋冬季气团轨迹多起源于内蒙古,经河北、天津、山东等省市抵达青岛.  相似文献   

3.
北京一次持续性雾霾过程的阶段性特征及影响因子分析   总被引:11,自引:1,他引:10  
利用北京地区高时间分辨率观测资料对2009年11月3—8日一次持续性雾霾天气过程中的气象因素和气溶胶演变特征进行了分析。结果表明,该次雾霾过程具有明显的阶段性特征,前期以霾为主,中期发展为雾霾交替,后期随着相对湿度减小再次转换为霾并最终消散。边界层逆温是低能见度过程形成的必要条件,但并不最终决定雾霾低能见度强度。相对湿度和PM2.5浓度是决定能见度大小的两个关键影响因子,对能见度的影响体现出阶段性特征。大部分时段PM2.5浓度是影响能见度的主要因子,当能见度小于1 km时,能见度变化更多受相对湿度影响。不同的情景计算表明,控制PM2.5浓度对于改善本次过程的能见度有重要作用。  相似文献   

4.
为了监测北京奥运主场馆附近大气颗粒物的污染状况以及评估奥运污染源减排措施对北京大气颗粒物质量浓度变化的影响,利用颗粒物在线监测仪器TEOM于2007年和2008年夏季,在奥运主场馆附近的中国科学院遥感应用研究所办公楼楼顶对大气颗粒物PM10和PM2.5进行了连续同步观测。结果表明,2007年夏季监测点附近大气PM10与PM2.5质量浓度的平均值分别为153.9和71.2μg·m-3,而2008年夏季PM10与PM2.5质量浓度的平均值分别为85.2和52.8μg·m-3。与奥运前一年同时段相比,奥运时段大气PM10和PM2.5的质量浓度分别下降44.5%和25.1%。对比分析奥运前后的2次典型污染过程发现,空气相对湿度的增加和偏南气流输送的共同影响易造成大气颗粒物的累积增长,而降雨的湿清除作用和偏北气流则会使大气颗粒物浓度迅速降低。在相近的气象条件下,奥运前后的污染过程中,大气细粒子的日均增长速率分别为25.1和13.9μg·m-3·d-1,而大气粗粒子的日均增长速率分别为20.8和2.2μg·m-3·d-1,奥运时段污染累积过程中大气粗、细粒子的增长速率分别显著低于和略低于奥运前同时段污染过程中颗粒物的增长速率。污染源减排措施的实施是奥运期间大气颗粒物质量浓度降低的主要原因,从控制效果来看,奥运期间实施的污染源减排措施对大气粗粒子的控制效果明显好于大气细粒子。  相似文献   

5.
2014年3月13日至4月20日在福建三明市利用PM2.5中流量采样器采集大气中PM2.5膜样品,测定了PM2.5的质量浓度,并用热/光碳分析仪和离子色谱分析了其组分变化特征.结果表明,三明市观测期间PM2.5的平均质量浓度为73.61±0.73 μg/m3,有机碳(OC)和元素碳(EC)的平均质量浓度分别为7.26±1.00和5.63±0.27 μg/m3,水溶性离子中SO42-、NH4+、NO3-和Na+的质量浓度分别为18.08±12.19、4.18±3.56、2.77±1.16和2.73±0.23 μg/m3,总和占总水溶性离子的87.76%.结合后向轨迹分析了福建三明市的污染物来源特征.该地区OC/EC的平均比值小于2,SOC(二次有机碳)生成量很少,主要以一次有机污染物为主,OC、EC与K+的相关性分析表明OC、EC与K+的来源相近,可以判断OC、EC绝大部分来源是生物质燃烧产生的污染物.在水溶性离子分析中,观测期间NO3-/SO42-为0.159±0.02,表明三明市主要以固定源为主,机动车辆等移动源贡献较少.  相似文献   

6.
气溶胶质量密度是气溶胶重要的参数,它影响着大气中复杂的化学反应,也与气溶胶的传输过程和空间分布息息相关.基于MERRA-2再分析资料提供的气溶胶柱质量密度数据,研究了我国塔里木盆地1980—2018年长时间序列的沙尘气溶胶柱质量密度的时空分布特征.结果表明,沙尘气溶胶和沙尘PM2.5气溶胶柱质量密度有很大的变化范围,平均值分别为0.33和0.086 g/m2,同时具有明显的年际、月和季节变化特征.沙尘气溶胶和沙尘PM2.5气溶胶柱质量密度的年平均值在0.24~0.41和0.06~0.11 g/m2范围内变化;春季最大,其平均值分别为0.47和0.12 g/m2,冬季最小,其平均值分别为0.13和0.04 g/m2;月平均值最大出现在5月,分别为0.57和0.14 g/m2,最小在1月,分别为0.1和0.03 g/m2.  相似文献   

7.
自2014年以来,中国细颗粒物(PM2.5)浓度大幅度下降,但臭氧(O3)浓度逐年缓慢上升,厘清PM2.5和O3(P-O)相关性尤为关键.在本研究中,2014—2019年北京和南京PM2.5年均质量浓度下降幅度分别为-6.86和-6.15 μg·m-3·a-1;而日最大8小时平均O3质量浓度(MDA8 O3)年均增长幅度为1.50和1.75 μg·m-3·a-1.研究期间,北京地区MDA8 O3质量浓度小于100 μg·m-3,P-O呈负相关;而当质量浓度大于100 μg·m-3时,P-O为正相关.通过Pearson相关系数研究P-O两者相关性.在两个城市每月相关性分析中,在每日时间尺度5—9月为强的正相关;而小时时间尺度11月至次年2月趋于负相关.在北京,P-O每月和季节相关性变化大于南京.在日变化中,夏季在16时为强的正相关,春秋两季在13—17时为弱的正相关,而在春、秋和冬季8时,却为强的负相关.  相似文献   

8.
使用Anderson-Ⅱ型9级撞击采样器测量了南京市鼓楼商业区、江北工业区、钟山风景区和宁六高速公路交通源春、夏、秋三季的大气气溶胶质量浓度。分析结果表明:南京市PM2.1和PM10的质量浓度存在明显的季节变化,秋季>春季>夏季;ρPM10春季为167.47 μg/m3,夏季为 85.99 μg/m3,秋季为238.99 μg/m3;ρPM2.1春季为59.66 μg/m3,夏季为42.80 μg/m3,秋季为100.15 μg/m3。不同季节中ρPM10ρPM2.1均存在较好的相关性,夏季相关性最好,相关系数为0.952;秋季次之,相关系数为0.783;春季相对较差,相关系数为0.613。城市不同功能区之间ρPM2.1ρPM10的质量浓度值差异很大,交通源>工业区>商业区>风景区。城市不同功能区的质量浓度谱分布基本一致,均为双峰型分布,峰值分别位于0.43~0.65 μm/m3和9.0~10.0 μm/m3。南京市春、夏、秋三个季节大气粒子质量浓度谱为双峰分布,粒子主要集中在0.43~3.3 μm/m3的粒径段。江北工业区ρPM10ρPM2.1质量浓度的相关系数为0.814,略高于鼓楼商业区的0.797。  相似文献   

9.
南京市城市不同功能区PM10和PM2.1质量浓度的季节变化特征   总被引:1,自引:0,他引:1  
使用Anderson-Ⅱ型9级撞击采样器测量了南京市鼓楼商业区、江北工业区、钟山风景区和宁六高速公路交通源春、夏、秋三季的大气气溶胶质量浓度。分析结果表明:南京市PM2.1和PM10的质量浓度存在明显的季节变化,秋季>春季>夏季;ρPM10春季为167.47 μg/m3,夏季为 85.99 μg/m3,秋季为238.99 μg/m3;ρPM2.1春季为59.66 μg/m3,夏季为42.80 μg/m3,秋季为100.15 μg/m3。不同季节中ρPM10ρPM2.1均存在较好的相关性,夏季相关性最好,相关系数为0.952;秋季次之,相关系数为0.783;春季相对较差,相关系数为0.613。城市不同功能区之间ρPM2.1ρPM10的质量浓度值差异很大,交通源>工业区>商业区>风景区。城市不同功能区的质量浓度谱分布基本一致,均为双峰型分布,峰值分别位于0.43~0.65 μm/m3和9.0~10.0 μm/m3。南京市春、夏、秋三个季节大气粒子质量浓度谱为双峰分布,粒子主要集中在0.43~3.3 μm/m3的粒径段。江北工业区ρPM10ρPM2.1质量浓度的相关系数为0.814,略高于鼓楼商业区的0.797。  相似文献   

10.
2010年11月16日至12月17日在南京、常州、苏州三城市设置采样点,24 h采集大气PM2.5样品,并测定其水溶性无机离子和元素的浓度,在此基础上讨论PM2.5及无机组分的时空分布特征。结果表明,采样期间,PM2.5污染较严重,且苏州最重,常州次之,南京最轻,南京、苏州、常州日均浓度分别是国家二级标准(75 μg/m3)的1.44、2.32、1.53倍;三市PM2.5离子组分中,阴离子均以SO42-和NO3-为主,阳离子以Ca2+和Mg2+为主;苏州Na+和Cl-之间的相关性较高,其受到海盐输送影响较大;三城市PM2.5中Ca是最主要元素,Al次之。运用主成分法分析南京、常州和苏州PM2.5的来源可知,三城市PM2.5受多个污染源影响,包括生物质燃烧、地表扬尘、五金工业及汽车尾气排放等。  相似文献   

11.
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   

12.
侯梦玲  王宏  赵天良  车慧正 《大气科学》2017,41(6):1177-1190
本文利用GRAPES_CUACE大气化学模式对京津冀地区2015年12月重度雾霾过程进行了模拟和评估。京津冀地区能见度和PM2.5模拟值与观测值的对比表明:该模式能较好地模拟京津冀地区能见度和PM2.5的逐日变化情况,但模式存在对伴随着重污染发生的低能见度模拟偏高的问题。以12月5~10日的重度雾霾过程为重点,针对地面风速、边界层高度、相对湿度、PM2.5及其对能见度的影响进行了详细分析,研究结果表明:污染过程中大部分地区过程平均风速低于2 m s-1,边界层平均高度低于600 m,相对湿度较高。模式低能见度模拟偏高可能因为:(1)模式模拟重雾霾时段的PM2.5极大值浓度偏低。(2)模拟相对湿度存在系统性偏低的误差,这一误差对能见度的影响表现为两方面,一是相对湿度会通过影响可溶性气溶胶的吸湿增长过程影响气溶胶质量浓度,导致气溶胶消光系数的计算偏低;二是目前模式中采用的能见度的参数化公式考虑了相对湿度对气溶胶吸湿增长的影响,没有考虑雾滴的直接消光作用。  相似文献   

13.
《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   

14.
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   

15.
利用3个架次的积分浊度仪和PCASP-100X(Passive Cavity Aerosol Spectrometer Probe)机载观测资料,分析了2013年山西夏季空中有云、无云和少云3种不同条件下气溶胶散射系数的分布特征,讨论了气溶胶散射系数垂直变化与气溶胶数浓度、气象条件的关系,并结合HYSPLIT(Hybrid of Single Particle Lagrangian Integrated Trajectory model)后向轨迹模型研究气溶胶的运动轨迹和可能的污染来源。结果表明:山西夏季空中气溶胶总散射系数变化范围为0~499 Mm-1,晴空气溶胶数浓度和总散射系数明显大于有云和少云时。气溶胶总散射系数一般随高度的增加而递减。造成气溶胶总散射系数、数浓度偏高的原因有下垫面污染源多、风速小、相对湿度高以及逆温层的存在。550 nm波段气溶胶后向散射比大于0.1,粒径0.1~0.5 μm的气溶胶粒子对散射影响最大,说明山西空中细粒子污染比较严重。气溶胶总散射系数与数浓度有一定的相关性。引起气溶胶总散射系数、数浓度较高的气团传输路径主要为西南路径,局地排放的气溶胶大于远距离传输的气溶胶对散射系数的贡献。  相似文献   

16.
The authors investigated variations of aerosol scattering and absorptive properties in a semi-arid climate Observatory in the Inner Mongolia of China and factors affecting the variation. They use integrated nephelometer and aethalometer observations collected in 2005 and 2006 at the Silinhot Observatory. The results are as follows. 1) in autumn and winter, the diurnal cycle of scattering coefficient exhibited a clear bi-modal variation, and the scattering coefficient was indicative of the type of sandy weather. 2) The concentration of black carbon (BC) aerosols was much higher in winter than in the other seasons with an evident bimodal diurnal variation. 3) When the wind speed was lower than 3.5 m s?1, the dilution effect of air evidently influenced the scattering coefficient and BC mass concentration; for the wind speed above 3.5 m s?1, there appeared to be little correlation between wind speed and scattering coefficient or BC mass concentration. 4) Atmospheric visibility calculated from the aerosol scattering and absorptive coefficients was in good agreement with the direct observation of visibility. 5) Absorption by aerosols accounted for 25% of the total extinction in December.  相似文献   

17.
Results are presented of monitoring measurements of the mass concentration of PM10 (particles with the size of less than 10 μm) and PM2.5 (less than 2.5 μm) fine-dispersed aerosol fractions at the Sainshand and Zamyn-Üüd stations located in the Gobi Desert of Mongolia. Revealed are the annual variations of the mass concentration of PM10 and PM2.5 fine-dispersed aerosol fractions at these stations in 2008. The maximum values of monthly mean concentration during the year were observed in May in the period of dust storms. On the days with the steady calm weather, the mass concentrations of PM10 and PM2.5 varied within 5–8 μg/m3 (PM10) and 3–5 μg/m3 (PM2.5) at the Sainshand station. During the dust storms, the maximum values of concentration exceeded 1400 μg/m3 (PM10) and 380 μg/m3 (PM2.5) that is by 28 (PM10) and 15 (PM2.5) times higher than the maximum permissible concentration for the European Union. Results are given of studying the frequency and duration of dust storms in recent 20 years (1991–2010) in the Eastern Gobi Desert.  相似文献   

18.
Continuous observations of mass concentration and elemental composition of aerosol particles (PM2.5) were conducted at Tongyu, a semi-arid site in Northeast China in the spring of 2006. The average mass concentration of PM2.5 at Tongyu station was 260.9±274.4 μg m^-3 during the observation period. Nine dust events were monitored with a mean concentration of 528.0±302.7 μgm^-3. The PM2.5 level during non- dust storm (NDS) period was 111.65±63.37 μg m^-3. High mass concentration shows that fine-size particles pollution was very serious in the semi-arid area in Northeast China. The enrichment factor values for crust elements during the dust storm (DS) period are close to those in the NDS period, while the enrichment factor values for pollution elements during the NDS period are much higher than those in the DS period, showing these elements were from anthropogenic sources. The ratios of dust elements to Fe were relative constant during the DS period. The Ca/Fe ratio in dust aerosols at Tongyu is remarkably different from that observed in other source regions and downwind regions. Meteorological analysis shows that dust events at Tongyu are usually associated with dry, low pressure and high wind speed weather conditions. Air mass back-trajectory analysis identified three kinds of general pathways were associated with the aerosol particle transport to Tongyu, and the northwest direction pathway was the main transport route.  相似文献   

19.
This study analyzes and compares aerosol properties and meteorological conditions during two air pollution episodes in 19–22 (E1) and 25–26 (E2) December 2016 in Northeast China. The visibility, particulate matter (PM) mass concentration, and surface meteorological observations were examined, together with the planetary boundary layer (PBL) properties and vertical profiles of aerosol extinction coefficient and volume depolarization ratio that were measured by a ground-based lidar in Shenyang of Liaoning Province, China during December 2016–January 2017. Results suggest that the low PBL height led to poor pollution dilution in E1, while the high PBL accompanied by low visibility in E2 might have been due to cross-regional and vertical air transmission. The PM mass concentration decreased as the PBL height increased in E1 while these two variables were positively correlated in E2. The enhanced winds in E2 diffused the pollutants and contributed largely to the aerosol transport. Strong temperature inversion in E1 resulted in increased PM2.5 and PM10 concentrations, and the winds in E2 favoured the southwesterly transport of aerosols from the North China Plain into the region surrounding Shenyang. The large extinction coefficient was partially attributed to the local pollution under the low PBL with high ground-surface PM mass concentrations in E1, whereas the cross-regional transport of aerosols within a high PBL and the low PM mass concentration near the ground in E2 were associated with severe aerosol extinction at high altitudes. These results may facilitate better understanding of the vertical distribution of aerosol properties during winter pollution events in Northeast China.  相似文献   

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