Advertent/inadvertent effect on ‘rainfall center’ displacement in Northern Israel

This study of cloud seeding and urbanization effects on the spatial rainfall distribution was carried out in two stages. In the first stage the location of a ‘rainfall center’ (the area with the rainfall maximum) for annual amounts of rainfall was established by applying the Distance Correlation Matrix (DISTCORMAT) technique. Besides ‘natural’ climatic fluctuations there are two other factors which could also cause a shift in the ‘rainfall center’, namely, cloud seeding operations and the inadvertent urban influences. Rainfall centers were computed for the two experimental cloud seeding periods and for a subsequent period of operational seeding.Comparison of the DISTCORMAT outputs revealed that the ‘rainfall centers’ are located, as expected, in the Upper Galilee for the first experimental period and later were displaced westward by 2–4 km. Since in the second random experiment the seeding flight route and target area were shifted eastward, it seems that there is no evidence supporting the cloud seeding rainfall excess determined by various statistical methods. However, it is possible to attribute the center's displacement to the massive urbanization process along the Mediterranean coastal plane.In the second stage only 40 rain stations in the extreme northern part of the country were used and the DISTCORMAT was computed separately for ‘seeded days’ and ‘non-seeded days’. The results indicate that, although the center moved eastward on ‘seeded days’ during the second experiment, it moved westward for the ‘non-seeded days’ sample. Thus the finding offers evidence of both effects: advertent cloud seeding and the inadvertent urbanization factor.     

我国西双版纳夜雨资源的农业气候分析

研究了西双版纳地区夜雨及雾雨的天气气候特征及时空分布规律,分析了夜雨、雾雨的形成机制及其农业气候意义。结果表明,本区降水呈夜雨与昼雨相均衡的状况,夜雨率达５４５％～５７７％,尤其是雾季和干热季可分别达７１４％、７０６％。夜雨形成多是山风环流造成的地形雨,雨强小,雨时长,因而对作物的有效性高。夜间雾雨则在作物生态环境中起着至关重要的作用,可部分缓解干旱季节作物需水的不足。因此,深入探讨夜雨和雾雨资源是制定有效防御干旱对策的重要依据。     

Effects of acidic deposition on the erosion of carbonate stone — experimental results from the U.S. National Acid Precipitation Assessment Program (NAPAP)

One of the goals of NAPAP-sponsored research on the effects of acidic deposition on carbonate stone has been to quantify the incremental effects of wet and dry deposition of hydrogen ion, sulfur dioxide and nitrogen oxides on stone erosion. Test briquettes and slabs of freshly quarried Indiana limestone and Vermont marble have been exposed to ambient environmental conditions in a long-term exposure program. Physical measurements of the recession of test stones exposed to ambient conditions at an angle of 30° to horizontal at the five NAPAP materials exposure sites range from ∼ 15 to ∼ 30 μm yr⁻¹ for marble, and from ∼ 25 to ∼ 45 μm yr⁻¹ for limestone, and are approximately double the recession estimates based on the observed calcium content of run-off solutions from test slabs. The difference between the physical and chemical recession measurements is attributed to the loss of mineral grains from the stone surfaces that are not measured in the run-off experiments. The erosion due to grain loss does not appear to be influenced by rainfall acidity, however, preliminary evidence suggests that grain loss may be influenced by dry deposition of sulfur dioxide between rainfall events. Chemical analyses of the run-off solutions and associated rainfall blanks suggest that ∼ 30% of erosion by dissolution can be attributed to the wet deposition of hydrogen ion and the dry deposition of sulfur dioxide and nitric acid between rain events. The remaining ∼ 70% of erosion by dissolution is accounted for by the solubility of carbonate stone in rain that is in equilibrium with atmospheric carbon dioxide (“clean rain”). These results are for marble and limestone slabs exposed at an angle of 30° from horizontal. The relative contribution of sulfur dioxide to chemical erosion is significantly enhanced for stone slabs having an inclination of 60° or 85°. The dry deposition of alkaline particulate material has a mitigating effect at the two urban field exposure sites at Washington, DC, and Steubenville, OH.     

An improved wet deposition map of the United Kingdom incorporating the seeder—feeder effect over mountainous terrain

Data of the mean annual rainfall at 4000 sites across the United Kingdom during the period 1986–1988 have been used. These were combined with measurements of the concentrations of principal ions in rainfall at 59 rural lowland sites. The data have been modified to account for the higher concentrations of ions dissolved in rain water measured in mountainous areas. This occurs due to the scavenging of polluted hill caps clouds by less-polluted raindrops. It was assumd that scavenged cloudwater concentrations were double those of the local rainfall. The results show that the annual deposition by rainfall of pollutant ions over high ground is much higher than had previously been thought. Relative to the original scheme, which assumed ion concentrations were constant with height, the new scheme calculated increases in deposition of up to 76%. Rainfall was found to be more polluted near the east coast of Britain. However, the highest annual pollutant deposition by rainfall occurred in the mountainous regions near the west coast, such as the Lake District and Snowdonia, due to the high rainfall in these areas.     

Studies on the effects of air pollution on limestone degradation in Great Britain

The CEGB and the Cathedrals Advisory Commission for England formed a Joint Working Party in 1985 to promote a research programme aimed at improving the understanding of the relationships between stone decay, atmospheric pollution and other factors. The programme has included exposure of limestone samples at York Minster and eight other sites in England and Scotland selected to give a mix of urban, marine and rural locations. All of the sites have comprehensive air pollution and meteorological monitoring and measurement of rainfall chemistry. At two sites samples have been fumigated with controlled levels of sulphur dioxide.Over all sites, there was a significant trend to increased weight loss with increase in average sulphur dioxide concentration, but a negative trend with total nitrogen oxides and with nitrogen dioxide. For sample exposures longer than 200 days, the sulphur dioxide dependence at the inland Liphook fumigation site was about half that found near the coast at Littlehampton. There was no significant trend to increase weight loss with total rainfall amount for the complete data set, but the analysis was dominated by the very wet Scottish site, which experienced the lowest average concentrations of air pollutants.A theoretical model for the chemical dissolution of rainwashed limestone has been derived from consideration of the ion and mass balances between the incident rain water and run-off water. The model has been fitted to the measured loss rates from the stonework field trials. With the exception of the very wet Scottish site, the difference between the stone loss rate, calculated from the model, and the mean measured loss rate for any particular exposure was generally smaller than the variation between the triplicate samples. Variation in the dry deposition velocity between sites and exposure periods does not appear to have been a very significant factor, and no residual effect due to the concentrations of nitrogen oxides was found. The natural solubility of limestone in water was the dominant term in describing the stone loss, and neutralization of the rainfall acidity the least significant. The volume of the intercepted rainfall and the variation in the pH of the run-off water with rainfall intensity have been identified as the two most significant terms which require more precise quantification. The data from the inland fumigation site used in the model predict a stone loss due to sulphur dioxide in the air of less than 1 μm yr⁻¹ surface recession per ppb SO₂.     

降雨强度对洱海流域凤羽河氮磷排放的影响

降雨形成的径流携带各种陆面物质进入河流湖泊是导致水质变化的重要因素,而不同降雨强度下的河流氮磷输出特征均有所差异,因此,为阐明雨强对高原湖泊典型流域污染物排放的影响,本研究以洱海流域上游的凤羽河为研究对象,基于连续3 a(2011～2013年)的出口断面水质水量监测,分析了4种降雨强度(小雨、中雨、大雨、暴雨)对水体氮磷浓度和形态的影响.结果表明,降雨强度对凤羽河氮磷排放的影响显著,所有组分的氮和磷浓度平均值在小雨(10 mm)和中雨(10～25mm)时较低,在大雨(25～50 mm)和暴雨(50～100 mm)时较高;氨氮(NH_4+-N)(57. 14%～76. 85%)占总氮(TN)的质量分数大于颗粒态氮(PN)(23. 15%～42. 86%),溶解态总磷(TDP)(22. 73%～28. 00%)占总磷(TP)的质量分数小于颗粒态磷(PP)(72. 00%～77. 27%);不同形态的氮浓度比较为:TN NH_4+-N PN;不同形态的磷浓度比较为:TP PP TDP.     

基于DEM数据的HEC-HMS和Vflo降雨特征模拟对比研究——以北京密云区为例

选用密云地区30 m和90 m DEM数据并运用ArcGIS软件提取该地区DEM数据的水文地理信息,通过分析水文模型HEC-HMS、EPASWMM和Vflo后选择应用HEC-HMS和Vflo模型对该地区降雨进行分析.同时,统计分析密云地区过去30年(1989—2018年)的降雨数据,并结合研究区水文情况,基于密云地区普通降雨、暴雨、大暴雨和特大暴雨的降雨数据选用HEC-HMS和Vflo软件进行水文模拟.结果表明,HEC-HMS和Vflo软件可有效地模拟密云地区的降雨情况.HEC-HMS和Vflo软件输出的仿真结果很好,仿真模型的确定系数均大于0.82.分析HEC-HMS软件输出的普通降雨、暴雨、大暴雨、特大暴雨的降雨强度及其它参数,发现降雨强度越小模拟结果越接近实际数值,基于Vflo水文模拟软件也有相同结果.这同时也说明在对暴雨、大暴雨和特大暴雨进行水文模拟时需要开发或优化相应软件来满足实际需求,最终为生态系统建设提供一定的研究基础.     

The sensitivity of modeled sulfate wet deposition to the meteorological values used as input

Variations in the wet deposition of sulfate, resulting from uncertainties in key meteorological variables, have been calculated using a scavenging model with a steady-state meteorology and a time-dependent, non-linear chemical mechanism. Input data to initialize this model are representative of data measured during an actual storm event. The results are presented in terms of the deposition uncertainty that would result if the maximum prescribed uncertainty occurred simultaneously in all input meteorological variables. For stratiform clouds, sulfate deposition uncertainties of up to 33% of the computed value were calculated. For convective clouds, the sulfate deposition uncertainties ranged from near 30% at low grid-averaged precipitation rates to near 60% at higher precipitation rates. The largest contributor to deposition uncertainty was the area of convective cloud coverage. For a mixed convective-stratiform cloud system, uncertainties in deposition remained below 40% as long as the convective contribution to total precipitation was less than 75% of the total rainfall amount. In the mixed convective-stratiform system, the uncertainties in deposition were associated principally with uncertain areas of cloud coverage and uncertain precipitation contributions by each cloud type. Uncertainties in precipitation rate, cloud top height, and cloud base height were of secondary importance for the mixed cloud system and contributed roughly equally to the remaining deposition uncertainty. In all simulations, uncertainties calculated as the standard deviation from the known value are about half of the maximum value.     

A numerical simulation of the chemistry of a rainband

Comparisons between the observations of a rainband and the results of a numerical simulation with a two-dimensional dynamical chemical model are presented. The simulation produced sulphate concentrations in the precipitation that agreed reasonably well with the observations, which suggests that the treatment of the major pathways for sulphate in the rain is satisfactory. Oxidation within the cloud was found to be a relatively unimportant pathway for this particular precipitation system, the two most important sources of sulphate in the rain being nucleation of sulphate aerosol and washout.     

模拟酸雨对马尾松和杉木幼树的影响

本实验模拟酸雨pH值为6.63(对照),4.5,3.0和2.0。实验结果表明,杉木针叶汁液pH值和土壤pH值随模拟酸雨pH值下降而降低,土壤比叶汁液更容易被酸化,也更难恢复。模拟酸雨对马尾松和杉木单位叶干重净光合速率影响不显著,最高酸度的模拟酸雨由于减少光合组织而显著降低单株净光合速率。模拟酸雨显著增大了马尾松和杉木呼吸速率。模拟酸雨对茎生物量没有影响,主根和叶生物量有减少的趋势,但不显著,须根生物量有显著减少,模拟酸雨抑制植物生长的机制是增大呼吸速率使物质消耗增加和减少光合组织,导致物质生产减少。     

酸雨对红色石灰土壤中Ca2+迁移及岩溶土壤生态系统的影响

为探讨酸雨对粤北岩溶区岩溶土壤中Ca迁移和流失的影响,选择酸雨频率和酸雨程度较高的我国广东省佛山市,开展自然降雨对红色石灰土壤中Ca2+的流失影响试验,于2011—2013年共收集到61次有效降雨产生的渗漏液,分析渗漏液中ρ(Ca2+)的变化情况,并间隔0.5 a左右测定供试土壤中的w(水溶性Ca)和w(TCa)(TCa为全钙),将试验3 a后供试土壤的w(有机质)、w(TN)、pH与供试源地土壤进行比较. 结果表明:①单位降雨造成的红色石灰土壤中Ca2+流失量与渗漏液中ρ(Ca2+)呈极显著正相关,与降雨量、渗漏液pH均呈正相关,而与雨水pH呈负相关,但不显著;单位降雨造成的土壤Ca2+净流失量达到2.16×10-5 g/(mm·kg),61次有效降雨造成的Ca2+净流失总量为0.05 g/kg. ②与蒸馏水及石灰岩采样点所在的坡麓洼地积水比较,酸雨明显增加了红色石灰土壤Ca2+流失量,但其影响因素复杂. pH为4.50~<5.65的轻度酸雨造成的土壤Ca2+流失量最大,其次是pH为5.65~6.29的非酸雨和pH<4.50的重度酸雨. ③降雨使石灰土壤中的w(TCa)呈持续减少趋势,2011—2013年供试石灰土壤中w(水溶性Ca)减少量为0.36 g/kg,并且呈明显的由上至下的减少迁移过程. ④与供试源地土壤相比,历经3 a酸雨淋溶的红色石灰土壤的w(有机质)和w(TN)均极显著增加,表层pH也极显著升高,意味着酸雨加速了土壤的分解转化,存在潜在的养分流失风险. 研究显示,酸雨不仅造成石灰土壤中Ca2+的加速流失和迁移,也加速了土壤中各类养分的分解转化,同时还会对岩溶地形、岩溶植物、流域水环境产生潜在或直接的影响.      

湖南省酸雨变化特征、现状及成因分析

依据湖南省1993-2000年监测酸雨的数据资料,对湖南省酸雨的变化特征、分布及目前的状况和成因进行了分析.结果表明,湖南省降水pH值小于5.0的强酸性降水地区主要分布在湘中南和西南部,弱酸性降水区则分布在湘中地区;除怀化和洪江两地外,湖南降水阴阳离子基本平衡;湖南地区降雨为典型的硫酸型降雨,酸雨的形成主要受局地源的影响,其次是土壤、地形、气候和中远距离的输送等自然因素的作用.笔者认为能源结构和工业污染物等社会因素在酸雨的形成中具有决定性的作用.      

太行山脉不同量级降雨侵蚀力时空变化特征

基于太行山脉及其周边地区76个气象监测站点1954-2016年逐日降雨数据,建立了基于不同量级侵蚀性年降雨量模拟年降雨侵蚀力的简易模型,并采用气候倾向率、小波周期分析、重心模型、Co-Kriging插值、Mann-kendall非参数趋势检验以及突变分析等方法,分析了不同量级降雨侵蚀力时空变化特征及其影响因素。结果表明：（1）太行山脉地区年降雨侵蚀力简易模型为y=0.182x₁^1.095+5.463x₂^0.982+9.401x₃^1.017+15.258x₄-26.753,且多年降雨侵蚀力呈小幅上升趋势,10年间上升了2.4 MJ·mm·hm^-2·h^-1·a^-1,同时存在约20年的主周期和6年的小周期变化,并在1996年发生显著突变;中雨和大雨侵蚀力63年间均呈上升趋势,而暴雨和特大降雨侵蚀力呈下降趋势;春秋两季主要受中雨和大雨侵蚀力的影响,而夏季则主要受特大降雨侵蚀力的影响。（2）太行山脉地区各量级降雨侵蚀力最大值主要分布于太行山脉东南部以及五台山地区,最小值主要分布于地区的东北部;运用重心模型发现各量级降雨侵蚀力重心在春夏季节整体向东部以及东北部地区进行迁移,而秋冬季节则向南部以及西南地区迁移,形成一个循环,且与冬夏季风的控制时间相符。（3）太行山脉地区不同量级降雨侵蚀力与侵蚀性降雨量均呈显著正相关（P<0.01）,大雨和特大降雨侵蚀力分别与纬度、海拔呈显著负相关（P<0.05）,这主要与副热带高压移动、地形、海拔以及自然地理环境等因素有关。     

Simulating study on the effect of acid precipitation on forest soil weathering

The effect of acid rain on the forest soils in China was discussed on the basis of simulating studies. The soils were collected from five typical areas, including Chongqing in Sichuan Province and Guiyang in Guizhou Province, where there has been heavier acid rain in southwest China, and Huitong in Hunan Province, Zhouzhi in Shaanxi Province, and Xinglong in Hebei Province, all of which were selected as control. Field investigation and sampling were made in the typical forests in all the above five areas. The relationship between pH values in precipitation and rates of soil weathering, the difference between the rates of soil weathering in different areas, and the cause of such a difference, have been worked out. The prediction was also conducted on the supply dynamics of nutrient and toxic elements in various forest ecosystems which were affected by acid deposition in order to understand the long-term effects of acid precipitation on the forest ecosystems studied.     

2012年丰都县酸雨特征及其相关分析

根据2012年丰都县降水监测资料,对该地区的酸雨状况进行研究。结果表明,丰都县酸雨污染状况较重,各月的酸雨频率均在90％以上,降雨酸性的季节变化明显,冬季较夏季高。降雨成分中以SO2-4为主要阴离子,仍为硫酸型酸雨。相关矩阵分析表明,SO^2-4、NO3^-、F^-相关性较好。     

Wet and dry depostion fluxes above the North Sea

A hyperbolic-dilution relationship exists between the dissolved metal concentrations in rain above sea and the precipitation volume. The real wet flux can then be expressed solely as a function of the hyperbolic regression coefficients, the precipitation volume and the number of rain events. Hyperbolic regression coefficients were determined during a restricted period of sampling during which all rain events were sampled and analyzed. In addition, measuring the annual precipitation volume above sea allowed us to estimate the annual wet deposition flux.Dry deposition fluxes at sea were (1) measured using vasilinated plexiplates and (2) calculated using a dry deposition model and cascade impactor results. Despite the large uncertainties on the calculated dry deposition fluxes, results obtained with both methods agree within a factor of 2.3. Resuspension fluxes of the trace metals are negligible compared to the deposition fluxes.     

Hydrological eco-service of rubber plantations in Hainan Island and its effect on local economic development

The impacts of economic forest on global environmental change(GEC) are one of the hot issues in environmental study. Based on the 3-year observation data and 40-year climate data, GEC and analysis of the hydrological dynamic characteristics of rubber plantations and estimate of the water balance in the rubber plantations in Hainan Island were made. The results showed that the rainfall intercepted by thecanopy of the plantations accounted for 11.4-5 % of the annual rainfall, the total runoff for 23.71%, the total evaporation and transpiration for 63.24%, the soil moisture storage for 1.6%. Analysis of the 40year rainfall data in the 19 counties of Hainan Island during 1951—1990 showed that the large-scale substitution of the natural vegetation with the rubber plantations had no significant effect on the local rainfall in Hainan Island. The main reasons are (1) 80% of the rainfall in Hainan is brought by typhoons; (2) the proportion of 11.6% rubberplantations in total forest coverage in Hainan is not enough to influence the local rainfall in Hainan Island; and (3) although the rubberplantation is artificial vegetation, it has the similar function to the tropical rain forest. Analysis of the total water resource and I‘otal GDP ofHainan in 1997 showed that the economic benefit resulted from the water resource was 1.0 RMB Yuan/m3 . The value of hydrological of therubber plantation in Hainan was 113.9 million RMB Yuan/a when compared with the tropical rain forest. The paper reaches conclusion that the hydrological eco-service function of rubber plantation has been enhanced after transformed from natural vegetation, which includes the natural service and powerful social service.     

广州市东郊的降水监测及其理化特征

本文采用1982年至1987年广州市东郊的降水监测资料,初步探讨了该区酸雨污染特征。结果表明:广州市东郊酸雨污染严重,降水酸度逐年上升,雨水中阴阳离子浓度以SO₄2-和NH₄+最高。不同天气系统酸雨频率不同。      

福建土楼夯土墙风驱雨侵蚀损伤预测研究

世界文化遗产福建土楼地处中国东南沿海,年降雨高达1 600 mm,频繁遭受台风和极端天气袭击,每当台风登陆时,狂风挟着暴雨常常侵蚀危害着土楼建筑,风驱雨冲击侵蚀土楼夯土墙已成为土楼建筑的主要损坏形式。论文通过分析风驱雨作用下雨滴的运动形式及降雨特征,采用CFD数值模拟及风洞试验的方法完成数值风洞准确性模拟,以数值风场为基础加入降雨模型,考虑多种雨强和风速相互组合,分析风驱雨对土楼夯土墙的风雨侵蚀影响,揭示了夯土墙风雨侵蚀的内在规律。并通过当地一份气象统计资料作为算例,预测土楼年平均侵蚀损伤量在0.4~2.6 mm之间,所得结果为土楼的维护加固和开发利用提供了科学依据,也为其他生土建筑研究提供借鉴和参考。     

重庆市渝中区20年酸雨污染变化趋势及成因分析研究

以重庆市渝中区降雨及大气监测数据为基础,对重庆市渝中区近二十年酸雨污染的变化趋势、降水中化学成分变化进行分析,并从致酸源、地理因素、气象因素等方面探讨了重庆市渝中区酸雨污染的主要成因.结果表明:重庆市渝中区酸雨污染不仅来自于本区,还受外区输入性污染影响,特殊的地理环境和不利的大气扩散条件加重了酸雨污染的程度;近年来降雨pH总体上升,酸雨污染有所减轻;酸雨污染由煤烟型污染向石油型污染转变.