伊宁市降水化学成分及来源分析

降水是大气中主要和次要污染物的重要收集器,是大气中颗粒物和气态污染物最好的清除剂。本文利用离子色谱分析了2011年伊宁市90个降水样品,结果表明,该区降水pH月均值在5.27—7.1之间,年均值为6.26,电导率变化范围为34.64~63μs·cm~(-1),年均值为45.7μs·cm~(-1)。降水中主要离子浓度排序为Ca~(2+)SO_4~(2-)NH_4~+Mg~(2+)Cl~-NO_3~-Na~+F~-K~+,Ca~(2+)是最主要的阳离子,年均值为421.76μeq·L~(-1),SO_4~(2-)是最主要的阴离子,年均值为149.09μeq·L~(-1),表明伊宁降水中的致酸物质主要是硫酸盐。总离子浓度季节变化特征表现为春夏季高,秋冬季低,总离子浓度明显低于乌鲁木齐和沈阳,与北京类似,远高于杭州、广州,表明伊宁降水污染比北方城市轻,但是陆源贡献远大于南方城市。FA平均值为0.003,表明99.7%的降水酸度被碱性成分中和,NF计算结果表明Ca~(2+)的中和能力最强,其次是NH_4~+。从相关分析和因子分析来看,F~-、SO_4~(2-)、NO_3~-、Cl~-、NH_4~+主要受人为源的控制,Ca~(2+)、K~+主要来源于土壤和浮尘,Na~+、Mg~(2+)主要来源为土壤盐碱化、风化、干旱浮尘等自然源。     

成都典型秸秆燃烧季节PM2.5中化学成分研究

采集2012年春季和秋季成都城区的PM2.5(空气动力学当量直径小于等于2.5μm的颗粒物,即细颗粒物)样品,分析得到水溶性离子、有机碳(OC)和元素碳(EC)等化学成分。结果表明,春季和秋季PM2.5的浓度分别为101±64μg m~(-3)和88±30μg m~(-3),是环境空气质量标准(GB3095-2012)日均值的1.3倍和1.2倍。基于K~+、OC/EC(OC浓度/EC浓度)和K~+/EC(K~+浓度/EC浓度)指标判别生物质燃烧事件,结果发现春、秋季生物质燃烧期间PM2.5中OC、EC和K~+、Cl~-等成分明显高于非生物质燃烧期;SO_4~(2-)、NH_4~+、Ca~(2+)、Mg~(2+)、NO_3~-、Na~+等其它水溶性离子浓度在生物质燃烧期均有不同程度升高。春、秋季生物质燃烧期间OC浓度分别是非生物质燃烧期的4.2倍和1.8倍,EC为非生物质燃烧期的2.3倍和2.3倍。K~+和Cl~-浓度在春季生物质燃烧期超过平均值的3倍,在秋季生物质燃烧期超过平均浓度的0.8倍和0.9倍。     

苏州市大气PM_(2.5)中水溶性无机离子的源解析及其气象因子分析

为了探明PM_(2.5)中水溶性无机离子的来源和气象因子对其浓度变化的影响,利用2012年2、5、8和11月苏州市PM_(2.5)中水溶性无机离子浓度和本站气象观测数据,分析了苏州市水溶性无机离子的时间变化特征,解析了当地PM_(2.5)中水溶性无机离子的主要来源,探讨了气象因素对离子组分的影响。结果表明:(1)苏州市PM_(2.5)中水溶性无机离子年均浓度大小依次为:SO_4~(2-)NO_3~-NH_4~+Na~+Cl~-K~+Ca~(2+)Mg~(2+)F~-;SO_4~(2-)、NH_4~+和NO_3~-为PM_(2.5)中最重要的3种水溶性无机离子物种,其总和占PM_(2.5)总质量浓度的50.9%。各离子的季节浓度特征均为冬季最高、夏季最低。(2)通过运用主成分分析法对苏州市PM_(2.5)中水溶性无机离子进行来源分类解析,发现第一类为二次污染源和生物质燃烧,其贡献率为32.84;第二类为道路扬尘及工业排放,其贡献率为19.99%;第三类为海盐污染,其贡献率为18.43%。(3)通过水溶性无机离子与气象条件的相关性分析发现,风向、风速和温度与水溶性无机离子浓度的相关性较显著,这三者是颗粒物浓度变化的主要影响因子。(4)利用HYSPLIT后向轨迹模式对外来污染物进入苏州市的轨迹进行聚类分析后发现:因受季风气候影响,苏州市外来污染物的输入路径存在明显的季节性变化特征,其中夏半年输送主径源自海上,冬半年主径源自内陆。     

城市降水酸度分布与气溶胶水冲刷

在湖南省邵阳市工业区测量表明,该区颗粒物含量处于相当高的水平,颗粒物的主要水溶性成分为Ca~(2 )、SO_4~(-)、NO_3~-、NH_4~ 和Na~ 。Ca~(2 )在大颗粒(dp>9.0um)富集度最高,而SO_4~(2-)在小颗粒(dp<2.0um)中最丰富。所有尺度的颗粒都具有中和酸的能力,随粒径增大而提高。讨论表明,颗粒物水冲刷对雨滴化学成分和酸度的影响对直径小于2000um的雨滴是相当灵敏的,这种影响主要由大颗粒提供。讨论结果与降水成分的监测资料相一致。气溶胶水冲刷机制有效地解释了城市酸雨频率的规律分布。     

辽宁农村代表区域降水离子组成及与气态污染物相关性

对辽宁农村代表区域站点——辽中县马龙村观测站2007年2月至2008年1月酸雨、气态污染物浓度观测资料进行了研究。结果表明：辽中站降水的化学组成阴离子主要为SO4^2-和NO3-阳离子主要为NH4和Ca2＋,SO4^2-／NO3-比值为2．9．Na＋／Cl-比值较大,大于1。各种离子浓度冬春季高,夏秋季较低,表明研究区域降水酸化与污染关系不显著。实测的9种主要阴离子、阳离子总浓度比（∑阴离子／∑阳离子）与降水pH值相关性不高,表明目前酸雨研究观测的主要9种阴阳离子不能完全包括降水中的离子组成。降水酸性与近地面污染气体浓度相关各异,pH与NOx、CO、NO2和O3浓度有较明显的负相关,与SO2浓度负相关不明显;降水pH值与颗粒物等碱性污染物浓度正相关明显。降水中主要致酸离子SO4^2-和NO3-的浓度与相应酸性气体污染物SO2和NOx近地面浓度的相关不明显。     

中国南极长城站1998年大气降水化学特征的初步研究

文中报告了 1998年 1～ 12月 ,在中国南极长城站 (6 2°13′S ,5 8°5 8′W ,海拔 10 .0m)采集的 115个有效降水样品的 pH值、电导率和化学组分分析结果。长城站地区降水的年平均 pH值为 5 .6 2 ,电导率年平均值为 85 .16 μS/cm。秋季期间降水的 pH值和电导率较高 ,其它季节较低。降水中最主要的离子为Cl-,Na+ ,其他离子按平均浓度值依次排列为SO42 -,Mg2 + ,Ca2 + ,K+ ,NO3 -,NH4+ 。除NO3 -,NH4+ 外 ,各主要离子浓度间呈显著正相关 ,表明其来源具有同一性。降水样品的离子组成比例与周围海区的海水接近 ,显示了海盐是降水中可溶性离子的主要来源 ,而其它源只对Ca2 + 有一定贡献。该地区的降水具有较典型的海洋性降水的化学特征     

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、窟内PM2.5和PM10~2.5中水溶性离子总浓度分别为6.1±4.0μg·m^-3、12.2±9.1μg·m^-3、3.7±0.8μg·m^-3和7.5±1.6μg·m^-3,SO₄^2-、Ca²⁺、NO3^-、Na⁺及Cl^-是主要组成,SO42-、NO3-和Ca2+之和在窟外和窟内PM2.5和PM10~2.5中占总离子比例分别为79.24%,76.81%,80.61%及77.74%,二次离子主要来自固定污染源;(3)PM2.5与PM10~2.5中各离子浓度的比值在窟外、内分别为0.33~0.88、0.25~0.94,9种水溶性离子在不同粒径粒子中富集程度有所差异,3-5月的沙尘、7-9月的降雨、11月农村农作物秸秆燃烧及冬季取暖燃煤等对水溶性离子都有一定影响,窟内PM2.5中游客数量与NH4+和NO^3-有一定的相关性(R2=0.27、0.35)、PM10~2.5中游客数量与NH4+有一定的相关性(R2=0.31);(4)沙尘天气下窟外和窟内的PM2.5与PM10-2.5中Cl-、SO₄^2-、Na⁺、K+和Ca²⁺的浓度增加,窟区微环境主要受区域环境气象因素影响,建议极端沙尘天气关闭洞窟;(5)莫高窟大气环境呈碱性;(6)PM2.5和PM10~2.5主要来源于当地秸秆燃烧、二次污染源、土壤沙尘及干涸的大泉河。     

辽宁农村代表区域降水离子组成及与气态污染物相关性

对辽宁农村代表区域站点辽中县马龙村观测站2007年2月至2008年1月酸雨、气态污染物浓度观测资料进行了分析。结果表明：辽中观测站降水的化学组成阴离子主要为SO₄^2-和NO₃^-,阳离子主要是NH^₄+和Ca₂⁺, SO^₄2-/ NO₃^-比值为2.9, Na⁺/Cl^-比值较大,大于1。各种离子浓度冬春季高,夏秋季较低,表明研究区域降水酸化与污染关系不显著。实测的9种主要阴离子、阳离子总浓度比（∑阴离子/∑阳离子）与降水pH值相关性不高,表明目前酸雨研究观测的主要9种阴阳离子不能完全包括降水中的离子组成。降水酸性与近地面污染气体浓度相关各异,pH与NO_x、CO、NO₂和O₃浓度有比较明显的负相关,与SO₂浓度负相关不明显;降水pH值与颗粒物等碱性污染物浓度正相关明显。降水中主要致酸离子SO₄^2-和NO₃^-的浓度与相应酸性气体污染物SO2和NOx近地面浓度的相关不明显。     

南京市降水化学特征及其来源研究

为了解南京江北地区降水化学特征,分析了2011年3—6月共25个降水日的109个降水样品中的主要水溶性离子,并利用后向轨迹模式探讨了降水气团来源.结果表明:1)南京地区3—6月降水主要受南、北2种气团影响,北方气团降水的主要离子浓度高于南方气团降水.2)海盐示踪法和相关性分析显示,降水中NO₃^-和SO₄^2-主要来自燃煤、工业排放和汽车尾气;Ca²⁺主要来自地壳源;Cl^-主要来自海洋;海洋源和陆源对Mg²⁺和K⁺都有贡献,Mg²⁺的陆源贡献大于海洋源贡献,K⁺受海洋源的影响程度要低于Mg²⁺.3)南、北气团初期降水的各离子浓度高于总降水的各离子浓度,且初期降水的主要离子的富集系数高于总降水.这说明在降水初始阶段,雨水对南京大气中污染物(气态污染物和颗粒物)的云下冲刷去除作用较强,降水的离子浓度最高,局地源对降水离子的贡献较明显.     

东南亚生物质燃烧对我国霾和降水的影响

基于生物质燃烧排放源清单、地面观测和数值模式对东南亚中南半岛生物质燃烧气溶胶的排放特征,以及其在2020年春季对我国云南地区霾天气和南方前汛期降水过程的影响进行了分析。结果表明:中南半岛生物质燃烧气溶胶排放主要集中于每年3—4月,排放峰值时段集中于3月下旬至4月上旬,主要排放区域为缅甸东部和老挝北部。中南半岛生物质燃烧气溶胶在地面主要影响我国云南南部城市的霾天气,缅甸的生物质燃烧气溶胶是最主要的贡献源。中南半岛生物质燃烧气溶胶在低空西南急流作用下,可以在800~600 hPa高度传输至我国华南和江南南部大部分区域上空。传输至我国南方上空的生物质燃烧气溶胶通过抑制对流性降水、增强非对流性降水,可以改变南方前汛期降水过程的空间分布,使降水更集中于切变线附近。     

COMPARATIVE ANALYSIS OF VARIOUS DATA OF AIR–SEA TEMPERATURE DIFFERENCE AND ITS VARIATION ACROSS SOUTH CHINA SEA IN THE PAST 35 YEARS

Using the International Comprehensive Ocean-Atmosphere Data Set(ICOADS) and ERA-Interim data, spatial distributions of air-sea temperature difference(ASTD) in the South China Sea(SCS) for the past 35 years are compared,and variations of spatial and temporal distributions of ASTD in this region are addressed using empirical orthogonal function decomposition and wavelet analysis methods. The results indicate that both ICOADS and ERA-Interim data can reflect actual distribution characteristics of ASTD in the SCS, but values of ASTD from the ERA-Interim data are smaller than those of the ICOADS data in the same region. In addition, the ASTD characteristics from the ERA-Interim data are not obvious inshore. A seesaw-type, north-south distribution of ASTD is dominant in the SCS; i.e., a positive peak in the south is associated with a negative peak in the north in November, and a negative peak in the south is accompanied by a positive peak in the north during April and May. Interannual ASTD variations in summer or autumn are decreasing. There is a seesaw-type distribution of ASTD between Beibu Bay and most of the SCS in summer, and the center of large values is in the Nansha Islands area in autumn. The ASTD in the SCS has a strong quasi-3a oscillation period in all seasons, and a quasi-11 a period in winter and spring. The ASTD is positively correlated with the Nio3.4 index in summer and autumn but negatively correlated in spring and winter.     

CHARACTERISTICS AND TRENDS OF CLIMATIC EXTREMES IN CHINA DURING 1959–2014

The spatial and temporal variations of daily maximum temperature(Tmax), daily minimum temperature(Tmin), daily maximum precipitation(Pmax) and daily maximum wind speed(WSmax) were examined in China using Mann-Kendall test and linear regression method. The results indicated that for China as a whole, Tmax, Tmin and Pmax had significant increasing trends at rates of 0.15℃ per decade, 0.45℃ per decade and 0.58 mm per decade,respectively, while WSmax had decreased significantly at 1.18 m·s~(-1) per decade during 1959—2014. In all regions of China, Tmin increased and WSmax decreased significantly. Spatially, Tmax increased significantly at most of the stations in South China(SC), northwestern North China(NC), northeastern Northeast China(NEC), eastern Northwest China(NWC) and eastern Southwest China(SWC), and the increasing trends were significant in NC, SC, NWC and SWC on the regional average. Tmin increased significantly at most of the stations in China, with notable increase in NEC, northern and southeastern NC and northwestern and eastern NWC. Pmax showed no significant trend at most of the stations in China, and on the regional average it decreased significantly in NC but increased in SC, NWC and the mid-lower Yangtze River valley(YR). WSmax decreased significantly at the vast majority of stations in China, with remarkable decrease in northern NC, northern and central YR, central and southern SC and in parts of central NEC and western NWC. With global climate change and rapidly economic development, China has become more vulnerable to climatic extremes and meteorological disasters, so more strategies of mitigation and/or adaptation of climatic extremes,such as environmentally-friendly and low-cost energy production systems and the enhancement of engineering defense measures are necessary for government and social publics.     

IMPACT OF ATMOSPHERIC LOW-FREQUENCY OSCILLATION ON THE IMMIGRATION OF NILAPARVATA LUGENS(STL) IN HUNAN AND JIANGXI PROVINCES

Various features of the atmospheric environment affect the number of migratory insects, besides their initial population. However, little is known about the impact of atmospheric low-frequency oscillation(10 to 90 days) on insect migration. A case study was conducted to ascertain the influence of low-frequency atmospheric oscillation on the immigration of brown planthopper, Nilaparvata lugens(Stl), in Hunan and Jiangxi provinces. The results showed the following:(1) The number of immigrating N. lugens from April to June of 2007 through 2016 mainly exhibited a periodic oscillation of 10 to 20 days.(2) The 10-20 d low-frequency number of immigrating N. lugens was significantly correlated with a low-frequency wind field and a geopotential height field at 850 h Pa.(3) During the peak phase of immigration, southwest or south winds served as a driving force and carried N. lugens populations northward, and when in the back of the trough and the front of the ridge, the downward airflow created a favorable condition for N. lugens to land in the study area. In conclusion, the northward migration of N. lugens was influenced by a low-frequency atmospheric circulation based on the analysis of dynamics. This study was the first research connecting atmospheric low-frequency oscillation to insect migration.     

A COMPARATIVE ANALYSIS OF ATMOSPHERIC AND OCEANIC CONDITIONS BEFORE THE OCCURRENCE OF TWO TYPES OF EL NIO EVENTS

The atmospheric and oceanic conditions before the onset of EP El Ni?o and CP El Ni?o in nearly 30 years are compared and analyzed by using 850 hPa wind, 20℃ isotherm depth, sea surface temperature and the Wheeler and Hendon index. The results are as follows: In the western equatorial Pacific, the occurrence of the anomalously strong westerly winds of the EP El Ni?o is earlier than that of the CP El Ni?o. Its intensity is far stronger than that of the CP El Ni?o. Two months before the El Ni?o, the anomaly westerly winds of the EP El Ni?o have extended to the eastern Pacific region, while the westerly wind anomaly of the CP El Ni?o can only extend to the west of the dateline three months before the El Ni?o and later stay there. Unlike the EP El Ni?o, the CP El Ni?o is always associated with easterly wind anomaly in the eastern equatorial Pacific before its onset. The thermocline depth anomaly of the EP El Ni?o can significantly move eastward and deepen. In addition, we also find that the evolution of thermocline is ahead of the development of the sea surface temperature for the EP El Ni?o. The strong MJO activity of the EP El Ni?o in the western and central Pacific is earlier than that of the CP El Ni?o. Measured by the standard deviation of the zonal wind square, the intensity of MJO activity of the EP El Ni?o is significantly greater than that of the CP El Ni?o before the onset of El Ni?o.     

ANALYSIS OF “BIMODAL PATTERN” STORM ACTIVITY CHARACTERISTICS OF THE BAY OF BENGAL

Storms that occur at the Bay of Bengal (BoB) are of a bimodal pattern, which is different from that of the other sea areas. By using the NCEP, SST and JTWC data, the causes of the bimodal pattern storm activity of the BoB are diagnosed and analyzed in this paper. The result shows that the seasonal variation of general atmosphere circulation in East Asia has a regulating and controlling impact on the BoB storm activity, and the “bimodal period” of the storm activity corresponds exactly to the seasonal conversion period of atmospheric circulation. The minor wind speed of shear spring and autumn contributed to the storm, which was a crucial factor for the generation and occurrence of the “bimodal pattern” storm activity in the BoB. The analysis on sea surface temperature (SST) shows that the SSTs of all the year around in the BoB area meet the conditions required for the generation of tropical cyclones (TCs). However, the SSTs in the central area of the bay are higher than that of the surrounding areas in spring and autumn, which facilitates the occurrence of a “two-peak” storm activity pattern. The genesis potential index (GPI) quantifies and reflects the environmental conditions for the generation of the BoB storms. For GPI, the intense low-level vortex disturbance in the troposphere and high-humidity atmosphere are the sufficient conditions for storms, while large maximum wind velocity of the ground vortex radius and small vertical wind shear are the necessary conditions of storms.     

LOW-FREQUENCY CIRCULATION AND EXTENDED-RANGE FORECAST IN CONNECTION WITH AUTUMN EXTREME HEAVY RAINFALL PROCESS IN HAINAN

Observed daily precipitation data from the National Meteorological Observatory in Hainan province and daily data from the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis-2 dataset from 1981 to 2014 are used to analyze the relationship between Hainan extreme heavy rainfall processes in autumn (referred to as EHRPs) and 10–30 d low-frequency circulation. Based on the key low-frequency signals and the NCEP Climate Forecast System Version 2 (CFSv2) model forecasting products, a dynamical-statistical method is established for the extended-range forecast of EHRPs. The results suggest that EHRPs have a close relationship with the 10–30 d low-frequency oscillation of 850 hPa zonal wind over Hainan Island and to its north, and that they basically occur during the trough phase of the low-frequency oscillation of zonal wind. The latitudinal propagation of the low-frequency wave train in the middle-high latitudes and the meridional propagation of the low-frequency wave train along the coast of East Asia contribute to the ‘north high (cold), south low (warm)’ pattern near Hainan Island, which results in the zonal wind over Hainan Island and to its north reaching its trough, consequently leading to EHRPs. Considering the link between low-frequency circulation and EHRPs, a low-frequency wave train index (LWTI) is defined and adopted to forecast EHRPs by using NCEP CFSv2 forecasting products. EHRPs are predicted to occur during peak phases of LWTI with value larger than 1 for three or more consecutive forecast days. Hindcast experiments for EHRPs in 2015–2016 indicate that EHRPs can be predicted 8–24 d in advance, with an average period of validity of 16.7 d.     

AN ATTRIBUTION ANALYSIS OF CHANGES IN POTENTIAL EVAPOTRANSPIRATION IN THE BEIJING–TIANJIN–HEBEI REGION UNDER CLIMATE CHANGE

Based on the measurements obtained at 64 national meteorological stations in the Beijing–Tianjin–Hebei (BTH) region between 1970 and 2013, the potential evapotranspiration (ET0) in this region was estimated using the Penman–Monteith equation and its sensitivity to maximum temperature (Tmax), minimum temperature (Tmin), wind speed (Vw), net radiation (Rn) and water vapor pressure (Pwv) was analyzed, respectively. The results are shown as follows. (1) The climatic elements in the BTH region underwent significant changes in the study period. Vw and Rn decreased significantly, whereas Tmin, Tmax and Pwv increased considerably. (2) In the BTH region, ET0 also exhibited a significant decreasing trend, and the sensitivity of ET0 to the climatic elements exhibited seasonal characteristics. Of all the climatic elements, ET0 was most sensitive to Pwv in the fall and winter and Rn in the spring and summer. On the annual scale, ET0 was most sensitive to Pwv, followed by Rn, Vw, Tmax and Tmin. In addition, the sensitivity coefficient of ET0 with respect to Pwv had a negative value for all the areas, indicating that increases in Pwv can prevent ET0 from increasing. (3) The sensitivity of ET0 to Tmin and Tmax was significantly lower than its sensitivity to other climatic elements. However, increases in temperature can lead to changes in Pwv and Rn. The temperature should be considered the key intrinsic climatic element that has caused the "evaporation paradox" phenomenon in the BTH region.     

Could the Recent Taal Volcano Eruption Trigger an El Ni?o and Lead to Eurasian Warming?

正The Taal Volcano in Luzon is one of the most active and dangerous volcanoes of the Philippines. A recent eruption occurred on 12 January 2020(Fig. 1a), and this volcano is still active with the occurrence of volcanic earthquakes. The eruption has become a deep concern worldwide, not only for its damage on local society, but also for potential hazardous consequences on the Earth's climate and environment.     

Revisiting the Concentration Observations and Source Apportionment of Atmospheric Ammonia

正While China’s Air Pollution Prevention and Control Action Plan on particulate matter since 2013 has reduced sulfate significantly, aerosol ammonium nitrate remains high in East China. As the high nitrate abundances are strongly linked with ammonia, reducing ammonia emissions is becoming increasingly important to improve the air quality of China. Although satellite data provide evidence of substantial increases in atmospheric ammonia concentrations over major agricultural regions, long-term surface observation of ammonia concentrations are sparse. In addition, there is still no consensus on