Primary Product Distributions from the Reaction of OH with m-, p-Xylene, 1,2,4- and 1,3,5-Trimethylbenzene

A study was conducted to examine the OH-initiated degradation products of the four title compounds in the presence of sub-part-per-million levels of NO_x. The oxidation was conducted in a dynamic reactor to minimize the conversion of the aromatic compounds. The experiments were designed to represent reaction pathways that occur in the atmosphere at ambient NO₂ concentrations. A wide range of ring-retaining and ring-cleavage products having widely varying yields were measured during the study. For m-xylene, the major primary products observed (with molar yields) were methyl glyoxal (0.40), 4-oxo-2-pentenal (0.12), glyoxal (0.079), and m-tolualdehyde (0.049). For p-xylene, the major primary products were p-tolualdehyde (0.103), 2,5-dimethylphenol (0.13), cis-3-hexene-2,5-dione (0.176), trans-3-hexene-2,5-dione (0.045), 2-methyl-butenedial (0.071), glyoxal (0.394), and methylglyoxal (0.217). Several other reaction products were measured at yields less than 3%. The primary products for OH + 1,2,4-trimethylbenzene were found as follows: methylglyoxal (0.44), glyoxal (0.066), cis-3-hexene-2,5-dione (0.13), trans-3-hexene-2,5-dione (0.031), biacetyl (0.114), 3-methyl-3-hexene-2,5-dione (0.079), and 2-methyl-butenedial (0.045). Six other (ring retaining) products were measured at yields less than 3%. The primary products for OH + 1,3,5-trimethylbenzene were methylglyoxal (0.90), 3-methyl-5-methylidene-5(2H)-furanone (0.1), 3,5-dimethyl-3(2H)-2-furanone (0.1), 3,5-dimethyl-5(2H)-2-furanone biacetyl (0.08), and 2-methyl-4-oxo-2- pentenal (0.05). Three other products were detected at molar yields less than 5%. In some cases, the yields for the ring fragmentation products could only be based on calibrations from surrogate compounds. Yields for several of the unsaturated dicarbonyl compounds have not been reported previously while yields for methylglyoxal, glyoxal, and biacetyl are largely consistent with previous reports. Some of the primary furanone products are the identical to those reported as secondary products in aromatic systems.     

Aerosol Optical Properties Affected by a Strong Dust Storm over Central and Northern China

Aerosol observational data at 8 ground-based observation sites in the Chinese Sun Hazemeter Network(CSHNET)were analyzed to characterize the optical properties of aerosol particles during the strong dust storm of 16-21 April 2005.The observational aerosol optical depth(AOD)increased significantly during this dust storm at sites in Beijing city(86%),Beijing forest(84%),Xianghe(13%),Shapotou(27%),Shenyang(47%),Shanghai(23%),and Jiaozhou Bay(24%).The API(air pollution index)in Beijing and Tianjin also had a similar rise during the dust storm,while the Angstrm exponent(α)declined evidently at sites in Beijing city(21%),Beijing forest(39%),Xianghe(19%),Ordos(77%),Shapotou(50%),Shanghai(12%),and Jiaozhou Bay(21%),respectively.Furthermore,The observational AOD andαdemonstrated contrary trends during all storm stages(pre-dust storm,dust storm,and post-dust storm),with the AOD indicating an obvious"Valley-Peak-Valley"pattern of variation,whileαdemonstrated a"Peak-Valley-Peak"pattern. In addition,the dust module in a regional climate model(RegCM3)simulated the dust storm occurrence and track accurately and RegCM3 was able to basically simulate the trends in AOD.The simulation results for the North China stations were the best,and the simulation for dust-source stations was on the high side,while the simulation was on the low side for coastal sites.     

Source identification of PM2.5 particles measured in Gwangju, Korea

The UNMIX and Chemical Mass Balance (CMB) receptor models were used to investigate sources of PM_2.5 aerosols measured between March 2001 and February 2002 in Gwangju, Korea. Measurements of PM_2.5 particles were used for the analysis of carbonaceous species (organic (OC) and elemental carbon (EC)) using the thermal manganese dioxide oxidation (TMO) method, the investigation of seven ionic species using ion chromatography (IC), and the analysis of twenty-four metal species using Inductively Coupled Plasma (ICP)-Atomic Emission Spectrometry (AES)/ICP-Mass Spectrometry (MS). According to annual average PM_2.5 source apportionment results obtained from CMB calculations, diesel vehicle exhaust was the major contributor, accounting for 33.4% of the measured PM_2.5 mass (21.5 μg m^− 3), followed by secondary sulfate (14.6%), meat cooking (11.7%), secondary organic carbon (8.9%), secondary nitrate (7.6%), urban dust (5.5%), Asian dust (4.4%), biomass burning (2.8%), sea salt (2.7%), residual oil combustion (2.6%), gasoline vehicle exhaust (1.9%), automobile lead (0.5%), and components of unknown sources (3.4%). Seven PM_2.5 sources including diesel vehicles (29.6%), secondary sulfate (17.4%), biomass burning (14.7%), secondary nitrate (12.6%), gasoline vehicles (12.4%), secondary organic carbon (5.8%) and Asian dust (1.9%) were identified from the UNMIX analysis. The annual average source apportionment results from the two models are compared and the reasons for differences are qualitatively discussed for better understanding of PM_2.5 sources.Additionally, the impact of air mass pathways on the PM_2.5 mass was evaluated using air mass trajectories calculated with the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) backward trajectory model. Source contributions to PM_2.5 collected during the four air mass patterns and two event periods were calculated with the CMB model and analyzed. Results of source apportionment revealed that the contribution of diesel traffic exhaust (47.0%) in stagnant conditions (S) was much higher than the average contribution of diesel vehicle exhaust (33.4%) during the sampling period. During Asian dust (AD) periods when the air mass passed over the Korean peninsula, Asian dust and secondary organic carbon accounted for 25.2 and 23.0% of the PM_2.5 mass, respectively, whereas Asian dust contributed only 10.8% to the PM_2.5 mass during the AD event when the air mass passed over the Yellow Sea. The contribution of biomass burning to the PM_2.5 mass during the biomass burning (BB) event equaled 63.8%.     

基于FY-4A卫星数据的短时强降水监测预警指标

选取2018—2021年汛期短时强降水天气过程,利用相关性分析、箱线图法和极值统计法,尝试研究FY-4A卫星产品在短时强降水天气过程中的监测预警指标。研究表明：(1)FY-4A卫星多通道数据可以作为短时强降水监测预警的定量化指标予以应用。(2)筛选出相关性较好的13项产品统计出短时强降水的监测预警指标,其中赋值类指标4项,数值判别类指标9项(含辅助指标3项);初步设定13项指标中有9项达标时,短时强降水会发生。(3)在评估基础上完善了指标,监测预警效果有所提高,TS评分提高5.4%,空报率降低2.7%,漏报率降低1.9%。     

不同高度建筑物上的下行地闪回击特征

为了研究不同高度建筑物上发生的下行地闪回击特征差异,对2009—2012年广州高建筑物雷电观测试验中获取的能确认接地点高度的58次下行负极性地闪的综合同步观测资料进行对比分析。结果表明:接地点高度小于等于200m和接地点高度大于200m两类地闪的回击次数和回击间隔时间的差异不明显,但接地点高度大于200m的地闪的首次回击电流幅值、继后回击电流幅值、首次回击光强脉冲的10%~90%波前时间及10%波前~50%波后半宽时间、继后回击光强脉冲的10%~90%波前时间及10%波前~50%波后半宽时间的算术平均值 (几何平均值) 分别为接地点高度小于等于200 m地闪的1.8(2.1),1.5(1.4),7.4(7.4),3.1(3.4),4.6(4.3) 和2.4(3.6) 倍。     

四川暴雨过程动力因子指示意义与预报意义研究

本文利用2010年8月18~19日四川盆地西部地区一次引发了泥石流等次生灾害的暴雨天气过程的数值模拟资料及0.5°×0.5°分辨率、每6 h一次的GFS(Global Forecast Model)预报资料,结合集合动力因子预报系统中的广义对流涡度矢量垂直分量、质量散度、垂直螺旋度、质量垂直螺旋度、水汽垂直螺旋度、热力垂直螺旋度、湿热力平流参数、密度散度垂直通量、散度垂直通量、热力散度垂直通量、水汽散度通量、广义 Q 矢量散度等12个动力因子成员对此次暴雨过程进行诊断分析和预报研究,结果显示:(1)集合动力因子预报系统中的动力因子对此次降水落区诊断效果良好;(2)各动力因子区域均值随时间的变化曲线都能表现出降水区域均值随时间变化曲线双峰形态,其中,广义 Q 矢量散度、水汽垂直螺旋度、热力垂直螺旋度、质量垂直螺旋度、垂直螺旋度与降水的相关系数较大(达0.9以上),对此次降水的诊断效果较好;(3)动力因子对此次强降水过程的发展演变具有一定的预报能力。     

A comprehensive study on the surface chemistry of particulate matter collected from Jeddah,Saudi Arabia

In this work, the X-ray Photoelectron Spectroscopy (XPS) technique is utilized to analyze the surface chemical composition of particulate matter (PM) which was collected from various locations at Jeddah, Saudi Arabia. The main elements found on the surface of PM are carbon (C), oxygen (O) and silicon (Si) with combined percentage of 89.4–94.9 while traces of nitrogen (N), calcium (Ca), aluminum (Al), sodium (Na), chlorine (Cl), manganese (Mg), and sulfur (S) were also present. The analyzed XPS chemical state of C, O and Si was further used to determine their bonding with other elements occurring over the surface of PM. Carbon was found in the form of carbides (18.86%), fluorides (2.39%) and carbonates (78.75%); oxygen was observed as oxides (21.05%) and hydroxides (73.42%) of other metals; and silicon was detected as silicones (12.16%), nitrides (82.53%) and silicates (5.25%). The particle size of a PM is also of great concern for health issues, and thus has been investigated by the Field Emission Scanning Electron Microscope (FESEM). The Energy Dispersive X-ray Spectroscopy (EDS) was employed for cross verification of detected elements by XPS.     

Source identification for fine aerosols in Mammoth Cave National Park

In this study, positive matrix factorization (PMF) was applied to the chemical composition data of the ambient PM_2.5 collected at the Mammoth Cave National Park, an IMPROVE site in Kentucky. Eight individual carbon fractions, four organic carbons (OCs), pyrolyzed organic carbon (OP) and three elemental carbons (ECs), were provided to the analysis. Nine sources including the well-distinguished gasoline emission and diesel emission were identified. Also, the back trajectories indicated the crustal factor in this study were likely caused by Saharan dust storms in the summer. The apportionment of nine sources was: gasoline emission (6.7%), diesel emission (3.1%), summer secondary sulfate (49.0%), winter secondary sulfate (0.6%), OP-rich secondary sulfate (16.2%), secondary nitrate (2.8%), Intercontinental dust plus soil (4.9%), wood smoke (13.6%), and aged sea salt (3.2%). The results of this study will help regularize the pollution control strategies in rural areas of Kentucky and upper mid-western US while demonstrating the feasibility of applying carbon fractions to the source apportionment of rural upper-Midwestern areas.     

Wet-bulb,dew point,and air temperature trends in Spain

Theoretical and Applied Climatology - This study analyses trends of mean (T m), maximum (T x), minimum (T n), dew point (T d), and wet-bulb temperatures (T w) on an annual, seasonal, and monthly...     

Physical,mineralogical and chemical properties of harmattan dust at Ile-Ife,Nigeria

Summary Meteorological conditions associated with the transport and deposition of harmattan dust particles in West Africa are discussed as well as particle-size distribution analyses of Saharan aeolian dust monitored at Ile-Ife (7.29 N, 4.34 E) nearly 2,000 km South-West of its predominant source region, the Chad Basin.Mineralogical analysis of the dust indicated that it is predominantly composed of quartz (> 70%) followed by microcline, kaolinite and traces of mica and halloysite. Chemical analyses indicated a predominance of SiO₂ (> 60%) followed by Al₂O₃ (17.4%), Na₂O (10.1%), Fe₂0₃ (5.6%), TiO₂ (3.33%), K₂O (1.88%), MgO (0.56%), and CaO (0.37%). The following trace elements were identified: Zn (931 ppm), Mn (834 ppm), Ni (113 ppm), Cr (103 ppm), Cu (106 ppm), Co (77 ppm) V (65 ppm) and Li (25 ppm).The effect of the poor visibility caused by the harmattan dust on aviation operation and safety as well as the health hazards posed on the respiratory system by the air-borne toxic elements should be of concern to relevant decision makers and should be further investigated.

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Zusammenfassung Vorliegende Studie behandelt meteorologische Bedingungen in Zusammenhang mit dem Transport und der Ablagerung von Harmattan-Staubpartikeln in Westafrika, als auch Partikelgrößenverteilungen, die in Ile-Ife (7.29N, 4.34E) aufgezeichnet wurden, beinahe 2000 km südwestlich von ihrer wichtigsten Ursprungsregion, dem Tschad-Becken.Die mineralogische Analyse des Staubes hat gezeigt, daß er im wesentlichen aus Quartz (> 70%) besteht. Chemische Analysen des Staubes wiesen hauptsächlich SiO₂ (> 60%), sowie Al₂O₃ (17,4%), Na₂O (10,1%), Fe₂O₃ (5,6%) TiO₂ (3,33%), K₂O (1,88%), MgO (0,56%) und CaO (0.37%) aus; an Spurenelementen wurden Zn (931 ppm), Mn (834 ppm), Ni (113 ppm), Cr (103 ppm), Cu (106 ppm), Co (77 ppm), V (65 ppm) und Li (25 ppm) nachgewiesen.Die Auswirkungen der durch den Harmattan-Staub stark geminderten Sichtweite auf den Flugverkehr und dessen Sicherheit sowie die gesundheitliche Beeinträchtigung der Atemwege durch giftige Aerosole sollten Gegenstand der Sorge staatstragender Kräfte als auch weiterer Forschungsbemühungen sein!

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With 5 Figures     

小麦秸秆还田量对晋南地区裸地土壤—大气间甲烷、二氧化碳、氧化亚氮和一氧化氮交换的影响

采用静态暗箱采样—气相色谱/化学发光分析相结合的方法,对晋南地区盐碱地不同小麦秸秆还田量裸地土壤夏、秋季(2008年6～10月)的甲烷(CH4)、二氧化碳(CO2)、氧化亚氮(N2O)和一氧化氮(NO)交换通量进行了原位观测。结果表明:观测期内,秸秆全还田(FS)、秸秆一半还田(HS)和秸秆不还田(NS)处理土壤—大气间CH4、CO2、N2O和NO平均交换通量分别为-0.8±2.7、-1.4±2.3、-6.5±1.8μg(C).m-2.h-1(CH4),267.1±23.1、212.0±17.8、188.5±13.6mg(C).m-2.h-1(CO2),20.7±3.0、16.3±2.3、14.7±1.7μg(N).m-2.h-1(N2O),3.9±0.5、3.4±0.5、3.0±0.4μg(N).m-2.h-1(NO)。交换通量表现出明显的季节变化趋势,灌溉、降雨和温度变化是影响该趋势的主要因素。相对于NS处理,FS和HS处理降低了累积CH4吸收量(66%和59%),增加了累积CO2(42%和12%)、N2O(41%和9%)和NO(30%和13%)排放量,因此,秸秆还田促进了农田土壤总的温室气体排放。计算得到FS和HS处理小麦秸秆的CO2、N2O、NO排放系数分别为73.4%±1.6%和43.3%±1.0%(CO2)、0.37%±0.01%和0.17%±0.00%(N2O)、0.06%±0.00%和0.05%±0.00%(NO),FS处理的排放系数显著高于HS处理,且均低于同一实验地种植玉米、施肥农田的小麦秸秆排放系数(N2O和NO排放系数分别为2.32%和0.42%)。可见,在采用排放因子方法估算还田秸秆CO2、N2O和NO排放量时,应考虑秸秆还田量、农作物种植和施肥因素的影响。     

不同施肥处理下双季稻田CH4和N2O排放的全年观测研究

选取湖南典型红壤双季稻田为研究对象,采用静态箱—气相色谱法对不施肥对照(CK)、常规施化肥(NPK)、新鲜稻草与化肥配施(RS+ NPK1)、菌渣与化肥配施(MR+ NPK1)、新鲜牛粪与化肥配施(CD+NPK2)和沼渣与化肥配施(BD+NPK2)等6个处理的CH4和N2O排放通量进行为期一年的观测(早稻、晚稻和休闲期...     

禹城地区光合有效辐射的计算方法

利用2005年7月-2006年10月在山东禹城对太阳辐射（包括光合有效辐射PAR、可见光辐射VIS、总辐射Q等）、气象要素等进行的4次综合观测资料,初步得到了朋R,VIS的日、季节变化特征并对其进行了分析,结果表明：各辐射的小时累计之比vIS／Q,PAR／Q,PAR／VIS相对稳定,其平均值分别为0．39,1．95（mol／MJ）,4．97（mol／MJ）,但它们均有明显的日、逐日、季节变化,并受水汽、气溶胶、云等因素的影响。同时建立了实际天气PAR,VIS的小时累计经验公式及其转换关系,计算值与观测值均比较接近。当考虑水汽和散射因子时,PAR,VIS的计算值与观测值的相对偏差分别为11．1％,10．6％。限于实际情况,可以只考虑水汽因子的作用来计算PAR和VIS的小时累计值,它们的相对偏差分别为13．3％,12．6％。水汽因子对于PAR,VIS的传输和计算具有重要作用。     

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 changes of freezing/thawing indices and their response to recent climate change on the Qinghai–Tibet Plateau from 1980 to 2013

Theoretical and Applied Climatology - The spatial and temporal changes of the ground surface freezing indices (GFIs), ground surface thawing indices (GTIs), air freezing indices (AFIs), and air...     

近50年华东地区夏季异常降水空间分型及与其相联系的遥相关

利用中国华东地区91个站点1961～2007年夏季 (6～8月) 逐日降水资料和NCEP/NACR再分析资料, 用旋转经验正交函数 (REOF) 方法将华东地区夏季降水场分为5个区域, 即I区 (闽赣地区)、II区 (江南)、III区 (长江中下游地区)、IV区 (江淮) 和V区 (黄淮)。这5个区域的夏季降水周期显著不同, 当I区降水的年际周期性强 (弱) 时, II、III、IV、V区降水年际周期性弱 (强)。I～V区夏季降水的年代际及年际变率的年代际变化显著, 且在年代际降水较少或由多变少或由少变多的转换时段, 容易发生较大的年际变化。各区降水异常形成的局地成因有所差别。其中, 江南南部、江南、沿江 (长江中下游) 受低层异常反气旋控制, 该异常反气旋使得这些地区出现水汽辐散, 与异常的非绝热冷却结合, 造成异常下沉气流, 导致干旱发生。对于江淮之间的地区, 由南侧异常气旋性环流和北侧反气旋环流的西部辐散气流控制, 造成水汽向南北两侧辐散, 导致降水偏少; 对于黄淮地区干旱, 可归因于位于蒙古高原上的反气旋异常和位于西太平洋上的气旋性异常之间的异常偏北气流造成该地区水汽的异常辐散所致。华东5个区域的夏季降水和不同类型的遥相关有关。闽赣地区降水受欧亚-太平洋型 (EUP) 遥相关影响; 江南地区降水则可能受东亚-太平洋型 (EAP)/太平洋-日本型 (PJ) 影响, 亦与太平洋-北美型 (PNA) 存在可能的联系; 长江流域则可能受东大西洋型 (EA) 和EAP型影响; 江淮地区降水则明显地受EA/EUP和PJ/EAP的共同影响, 而黄淮降水则与源于地中海地区向东北传播且通过北极涛动 (AO) 产生影响的波列存在联系。这5个区域的夏季降水异常还和东亚地区位涡、 南海夏季风、 Niño3、Niño4区海温、西太平洋副高变动等因子有关。     

基于CERES资料的新疆云物理参数时空分布特征

利用2011—2020年ERA5再分析降水资料、CERES云物理参数产品，分析新疆云参数的时空变化分布特征，归纳总结云物理参数与降水的相关性，结果表明：1）云水路径（冰相）值、云粒子有效半径（冰相）、云光学厚度与降水量的空间分布一致，均为山区最大，北疆次之，南疆最小。2）夏季（6—8月）在南、北疆、山区云水路径（液、冰相）、云顶（底）温度、云光学厚度与降水量呈同位相变化；云粒子有效半径（液、冰相）、云顶气压与降水量呈反位相变化。3）夏季（6—8月）北疆、山区的云水路径（液、冰相）值、云顶（底）温度、云光学厚度，南疆云光学厚度与降水量呈正相关；北疆云粒子有效半径（冰相），南疆云粒子有效半径（液相）、云顶气压，山区云粒子有效半径（液、冰相）、云顶气压与降水量呈负相关。     

The First Fengyun Satellite International User Conference

正National Satellite Meteorological Center, China Meteorological Administration, Beijing 100081, China(Received 16 January 2020; revised 28 February 2020; accepted 9 March 2020)Citation:Xian, D., P. Zhang, M. Fang, C. Liu, and X. Jia, 2021:The First Fengyun Satellite International User Conference.     

南京市主城区大气颗粒物来源探讨

在2005-05-03——05-27期间,用Anderson九级采样器在南京市两个采样点采集大气气溶胶样品,同时进行了部分排放源的采集。用X射线—荧光光谱仪(XRF)分析得到气样及源样中PM10的化学成分,分析了南京市大气气溶胶的元素质量谱分布,进行了PM10的富集因子分析,并应用化学质量平衡法(CMB)计算各类源对气溶胶PM10的贡献。结果表明,各类污染源对南京市气溶胶PM10的贡献率分别为:建筑尘(35.45%)、煤烟尘(22.13%)、土壤尘(20.27%)、硫酸盐(5.43%)、汽车尘(4.61%)、海盐(1.91%)、冶炼尘(1.69%)、其它源(8.51%)。文中还结合了南京市TSP和PM2.5的来源解析结果,分析了南京市不同粒径气溶胶颗粒物的污染特征。     

Studies on the northern early summer teleconnection patterns,their interannual variations and relation to drought/flood in China

By using the one-point correlation method, calculations have been made of the northern early summer 500 hPa teleconnection patterns. Seven teleconnection patterns are revealed, namely, the Western Atlantic (WA), the Eastern Atlantic (EA), the Eurasian (EU), the Bengal / Northern Pacific (BNP), the Western Pacific (WP), the East Asian / Pacific (EAP), and the Huanghe / East Asian (HEA) patterns. Their centers are determined and their yearly intensity indices (1951-1990) are calculated. On this basis the relationship between their interannual variations and the drought / flood in China is examined. It is noted that the EU, HEA and EAP wave trains are closely related to the drought/ flood in China. The HEA and EAP patterns strongly influence the precipitation in eastern China. For ex-ample, the fierce floods experienced in 1991 early summer over China are related to the weak EAP and strong HEA patterns.