The Precision of Precipitation Chemistry Measurements in the Canadian Air and Precipitation Monitoring Network (CAPMoN)

Precision estimates are presented for precipitation chemistry and depth measurements made by the Canadian Air and Precipitation Monitoring Network (CAPMoN). The estimates were made for daily measurements of ion concentration and precipitation depth as well as for weekly, 28-day, seasonal and annual precipitation-weighted mean concentrations and depths. The data on which the estimates are based were collected from collocated samplers at five CAPMoN sites during the period 1985 to 1993. The data pairs from the collocated samplers were used to calculate the between-instrument error defined as 1/2 times the difference between the paired sample concentrations (or depths). For all of the ion concentrations and depths, the between-sampler errors were found not to be normally distributed, but the normality of the distributions improved with the length of the (volume-weighting) time period considered. A set of quantitative measures of overall network precision were derived in absolute (mg L^-1) and relative (%) units. These included the Modified Median Absolute Deviation (M.MAD), the P90% probability values and the Coefficient of Variation (CoV). The latter, defined as the percent ratio of the M.MAD to the median concentration (or depth), represents the relative precision at the center of the error and concentration (and depth) distributions. Based on the CoV values, the relative precision of the CAPMoN measurements was very high (better than 4%) for SO ₄ ^2- , NO ₃ ^- , pH, H⁺, NH ₄ ⁺ , sample depth and standard gauge depth, and not as high (between 10 and <35%) for Cl^-, Na⁺, Ca²⁺, Mg²⁺, and K⁺. The ions with the lowest median concentrations had the poorest relative precision since so many of the concentrations were at or near the analytical detection limit. Except for the sample and standard gauge depths, both the absolute and relative precision improved with the length of the precipitation-weighting period. Detailed statistical testing established that the precision of the daily measurements is dependent on a number of factors, the most dominant being sample depth and concentration, i.e., the absolute precision improves with increasing sample depth and decreasing concentration. The strength of these relationships diminished with the length of the precipitation-weighting period being considered. Laboratory-related sources of imprecision were found to account for less than 4% of the overall daily measurement imprecision for most species, while field-related sources of imprecision accounted for the balance. Specialized plots are shown which allow data users to estimate the absolute and relative precision at any concentration and depth value.     

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根据近１０年１０７７个降水样品监测结果，进行统计分析，阐明了宜昌市存在酸雨污染，且日趋严重的趋势。从大气污染、气象、地形等因素方面初步探讨了该市酸雨的成因。     

中越边界—河口酸沉降的来源和发展趋势分析

河口当地无工业。燃料结构以柴禾为主，但８０年代降水酸度ＰＨ值为３．８０－５．１２平均为４．４，频率高达１００％。相距五年后，９０年代进行三年连续监测，酸 雨ＰＨ值为３．８２－６．９０，平均为４．９３，频率为９７．６％。     

"九五"期间昆明市盘龙区酸雨状况分析

本文通过对盘龙区‘‘九五"期间降水监测结果进行评价,得出昆明市中心区酸雨的变化趋势,并加以分析,提出对策建议.     

我国酸雨状况和对策

我国酸雨区面积占国土面积的30％，是世界第3大酸雨区，为控制酸雨发展，应将其防治工作纳入经济和社会发展计划，调整能源结构，治理工业排放，研发治理技术和设备，加强环境管理。     

二氧化硫浓度的垂直分布对云下雨水酸化的影响

用一物理化学模式讨论了云下雨水的酸化过程.参照重庆地区的实际情况,讨论了SO_2随高度指数分布和其它分布对酸化的影响及近地面层高浓度SO_2对酸化的影响.SO_2平均浓度与实际垂直分布相比较,地面雨水成份相差较小,用平均浓度代替实际垂直分布是可行的.     

2003年陕西持续性暴雨成因分析

对2003年发生在陕西的持续性暴雨分析认为: 乌山阻高与副热带高压的配置及稳定少动为这次持续性暴雨提供了有利的背景条件.贝湖低压底部分裂出小槽引导的冷空气与副高西北侧暖湿气流在高原东侧一带反复交绥是暴雨的主要成因.高低空急流耦合使高层辐散区迭加在低层辐合区的上方而产生强烈的上升运动,为深对流的发展提供了条件,促进了暴雨时中尺度系统的生成和维持.     

武汉市酸雨分布规律及其成因分析

综合了近几年武汉市酸雨以及大气环境的监测结果，对该市的酸雨污染现状进行了分析。武汉市的酸雨主要发生在偏西南方向，降水pH值由西向东和由南向北逐渐增大。武汉市的降水具有硫酸型特征，形成酸雨的主要致酸物质为SO2。由于大气稳定度的影响，武汉市的酸雨多出现在冬季。     

成都市区酸雨变化及降雨化学组成分析

依据成都市1995～2003年城区酸雨监测统计资料,本文对成都市城区酸雨的变化特征、离子化学组成进行了分析。结果表明:城区降水酸度变化呈现出一定的波动性,酸雨频变化表现出较大的波动性;1999年和2000年酸雨年均酸度及频率情况都较好,之后出现反弹;降水中离子含量高,雨水污染严重;降水中CSO2-的比值正在逐步缩小,酸雨状况转变为硫/CNO-34酸型和硝酸型并重的局面,大气污染物中NOx的贡献率正在升高。灰色关联分析表明:降水pH值与雨水中碱性阳离子的关联序为NH+4>Ca2+>Mg2+>K+>Na+;降水pH′值与雨水中酸性阴离子的关联序为Cl->F->SO2-3。4>NO-     

青藏高原东北侧突发性暴雨特征综合分析

对1970-2007年发生在青藏高原东北侧陕西的突发性暴雨研究发现,其夜间降水特点明显,对流层中层较强的偏南气流是突发性暴雨水汽输送贡献最大者和低层辐合的主要动力来源。偏南气流北伸的位置决定突发性暴雨落区偏南或偏北,300hPa一致的纬向12～20m·s-1强风速带为突发性暴雨提供高层抽吸作用。上述两点对突发性暴雨落区有一定的预报指示意义。云图分析显示,突发性暴雨多有中尺度云团配合,上升运动最大值的高度层与突发性暴雨落区地域位置有关。