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1.
华东典型地区大气硫沉降通量的观测和模拟研究   总被引：7，自引：1，他引：7       下载免费PDF全文
杨浩明  王体健  程炜  韩敏 《气象科学》2005,25(6):560-568
本文使用中国科学院常熟和鹰潭生态实验站和气象站的观测资料，应用区域酸沉降模式系统（RegADMS）和大叶阻力相似模型来研究华东地区不同下垫面条件上的大气硫沉降问题，定量估计了农田下垫面上大气硫化物的沉降通量。SO2和硫酸盐的干沉降速率使用大叶阻力相似模型来估计，使用与降水量有关的参数化方案来确定湿沉降系数。结果表明，常熟地区农田下垫面的大气硫沉降通量为19．0gm^-2 a^-1，其中干沉降占42％；而位于江西红壤地区的鹰潭站的大气硫沉降通量为10．4gm^-2a^-1，其中干沉降占83％。比较发现，两地硫干沉降通量绝对值相差不大，但其在总沉降通量中所占的份额有较大差异；常熟站的硫湿沉降通量比鹰潭站要大9．23gm^-2a^-1，该差异是由两地污染状况和气象条件的不同造成。华东地区的年硫沉降总量为1．88Mt（1Mt=10^6t），其中72．8％沉降在农田下垫面上。硫沉降中43％是干沉降，57％是湿沉降。  相似文献   

2.
The COSAM intercomparison exercise (comparison of large‐scale sulfur models) was organized to compare and evaluate the performance of global sulfur cycle models. Eleven models participated, and from these models the simulated surface concentrations, vertical profiles and budget terms were submitted. This study focuses on simulated budget terms for the sources and sinks of SO2 and sulfate in three polluted regions in the Northern Hemisphere, i.e., eastern North America, Europe, and Southeast Asia. Qualitatively, features of the sulfur cycle are modeled quite consistently between models, such as the relative importance of dry deposition as a removal mechanism for SO2, the importance of aqueous phase oxidation over gas phase oxidation for SO2, and the importance of wet over dry deposition for removal of sulfate aerosol. Quantitatively, however, models may show large differences, especially for cloud‐related processes, i.e., aqueous phase oxidation of SO2 and sulfate wet deposition. In some cases a specific behavior can be related to the treatment of oxidants for aqueous phase SO2 oxidation, or the vertical resolution applied in models. Generally, however, the differences between models appear to be related to simulated cloud (micro‐)physics and distributions, whereas differences in vertical transport efficiencies related to convection play an additional rôle. The estimated sulfur column burdens, lifetimes and export budgets vary between models by about a factor of 2 or 3. It can be expected that uncertainties in related effects which are derived from global sulfur model calculations, such as direct and indirect climate forcing estimates by sulfate aerosol, are at least of similar magnitude.  相似文献   

3.
The Asian Dust Aerosol Model 2 with the MM5 meteorological model has been employed to estimate the dust emission, dust concentration, and wet and dry deposition of dust in the Asian region for the month of March in 2010. It is found that the model simulates quite reasonably the dust (PM10) concentrations both in the dust source region and the downstream region of Korea. The starting and ending times of most dust events and their peak concentration occurrence times are well simulated. The monthly mean maximum surface dust concentration (PM10) is found to be 267???g?m?3 in the domain of central northern China (CNC). Monthly total maximum dust emission of more than 32?t km?2 and that of deposition of more than 25.4?t km?2 (dry deposition of 24?t km?2 and wet deposition of 1.4?t km?2) are found to occur in the domain CNC, whereas the monthly mean minimum surface dust concentration (PM10) is found to be 0.2???g?m?3 in the domain of the Tibetan Plateau, where the monthly total dust emission (4?kg?km?2) and the monthly total dust deposition (9?kg?km?2) are found to be minimum. This monthly total dust deposition of 9?kg?km?2 (dry deposition of 7?kg?km?2 and wet deposition of 2?kg?km?2) is as large as 2.25 times of that of emission (4?kg?km?2), suggesting net dust influx toward the Tibetan Plateau from the surrounding dust source regions. It is also found that the ratio of the total dust deposition to the total dust emission in the source region increases toward the downstream direction from 0.4 in the upstream source region of Taklimakan to 0.80 in the downstream source region of northeastern China. More than 90% of the total dust deposition is found to be contributed by dry deposition due to the lack of precipitation in the dust source region. The monthly mean dust concentration (PM10) is found to decrease with distance away from the dust source region. The monthly mean dust concentration of 62???g?m?3 over the Yellow Sea (YES) decreases to 4.3???g?m?3 over the Northwestern Pacific Ocean (NWP). The monthly total dust deposition in the downstream region is also found to decrease away from the source region from 2.33?t km?2 (dry deposition of 1.36?t km?2 and wet deposition of 0.97?t km?2) over the domain YES to 1.45?t km?2 (dry deposition of 0.16?t km?2 and wet deposition of 1.30?t km?2) over the domain NWP. A large amount of the total dust deposition over the seas is contributed by wet deposition (more than 90%), causing a small decreasing rate of the total dust deposition with distance from the source region. The estimated dust deposition could adversely impact the eco-environmental system significantly in the downstream regions of the Asian dust source region, especially over the seas.  相似文献   

4.
The authors present spatial and temporal characteristics of anthropogenic sulfate and carbonaceous aerosols over East Asia using a 3-D coupled regional climate-chemistry-aerosol model, and compare the simulation with the limited aerosol observations over the region. The aerosol module consists of SO2, SO4^2-, hydrophobic and hydrophilic black carbon （BC） and organic carbon compounds （OC）, including emission, advections, dry and wet deposition, and chemical production and conversion. The simulated patterns of SO2 are closely tied to its emission rate, with sharp gradients between the highly polluted regions and more rural areas. Chemical conversion （especially in the aqueous phase） and dry deposition remove 60% and 30% of the total SO2 emission, respectively. The SO4^2- shows less horizontal gradient and seasonality than SO2, with wet deposition （60%） and export （27%） being two major sinks. Carbonaceous aerosols are spatially smoother than sulfur species. The aging process transforms more than 80% of hydrophobic BC and OC to hydrophilic components, which are removed by wet deposition （60%） and export （30%）. The simulated spatial and seasonal SO4^2-, BC and OC aerosol concentrations and total aerosol optical depth are generally consistent with the observations in rural areas over East Asia, with lower bias in simulated OC aerosols, likely due to the underestimation of anthropogenic OC emissions and missing treatment of secondary organic carbon. The results suggest that our model is a useful tool for characterizing the anthropogenic aerosol cycle and for assessing its potential climatic and environmental effects in future studies.  相似文献   

5.
The interaction of formaldehyde with SO2 dissolved in the aqueous phase of clouds leads to the formation of hydroxymethane sulfonate. The impact of this process upon the gas-liquid equilibrium distribution of SO2 in rain clouds and the ensuing wet SO2 precipitation rate is explored. Model vertical SO2 distributions are derived from observational data for three atmospheric regions: continental polluted, continental remote, and marine. The wet deposition rate for SO2 in the polluted atmosphere increases by about a factor of two in the presence of formaldehyde compared with its absence. The effect is much stronger in the remote atmosphere leading to a potentially significant enhancement of wet SO2 deposition. In the marine atmosphere, wet deposition of SO2 may contribute as much as 35% to the total removal rate for SO2 by all processes including dry deposition and chemical conversion to sulfate.  相似文献   

6.
Changes in the frequency of precipitation as a result of a changing climate, as well as anthropogenic induced deposition of nitrogen (N), both have the potential to alter grassland productivity and diversity. Central U.S. weather patterns are dominated by three major air mass trajectories including regional sources from the Gulf of Mexico (marine tropical, Mt), the Pacific Northwest (mild pacific, mP), and the Desert Southwest (continental tropical, Ct). In this work, the Hybrid Single Particle Lagrangian Integrated Trajectory model was used to determine trends in the proportion of precipitation events from these air mass sources from 1983 to 2006 relative to Konza Prairie Biological Station (KPBS), KS. The annual volume-weighted mean (VWM) concentrations and wet deposition of a variety of precipitation dissolved solutes were linked to source regions north or south of KPBS. The proportion of precipitation events from Mt significantly increased, while the proportion of events from Ct and mP decreased significantly over the study period. The annual VWM concentrations of most solutes were typically higher from precipitation sourced to the north of KPBS. However, wet deposition of four ecologically relevant solutes (NH4+, NO3?, H+, and SO4?2) was higher from events from the southern region, likely due to higher precipitation amounts. The proportion of reduced N increased significantly over the study period but was not affected by source region despite the higher use of fertilizers for agriculture in the northern source region. Given the location of this site relative to three dominant air mass paths, future shifts in these patterns will likely impact wet nutrient deposition.  相似文献   

7.
To access the relative contribution of anthropogenic and biogenic sulfur sources to the sulfur budget in the Eastern Mediterranean, an area characterized by very high nss-     levels, measurements of both wet and dry deposition of sulfur were performed at a remote area on the island of Crete (Finokalia) during a 3-yr period (1996–1999). The estimation of dry deposition is based on both gaseous sulfur dioxide (SO2) and particulate phase non-sea-salt sulfate (nss-     ) and methane sulfonate (MSA) measurements. During the dry period, deposition of SO2 from long-range transport is the main component of anthropogenic sulfur deposition in the area. The results of the wet and dry deposition obtained at Finokalia have been compared with DMS emission from seawater obtained during two yearly surveys (1997–1998) in the Cretan Sea. Our results indicate that the contribution from biogenic sources to the sulfur budget in the Eastern Mediterranean, although negligible during winter, can account for up to 26% during summer.  相似文献   

8.
积云对二氧化硫和硫酸盐气溶胶作用的研究   总被引：1，自引：1，他引：0  
利用一个冰雹云模式与云化学模式耦合而成的二维积云化学模式,研究对流云的输送、微物理转化、云内化学过程、湿清除对SO2及硫酸盐气溶胶的作用。云化学模式的结果表明,由于SO2在向上输送的过程中可溶解于云水和雨水中,从而阻止了SO2向上部的转移,因此对气相SO2来说,云的输送是一个相当无效的过程,而液相清除起主要作用。硫酸盐气溶胶的收支分析表明,降水清除了1.67 mol的SO2-4,占气溶胶总量的64%,其中液态降水清除了0.72 mol,固态降水清除了0.95 mol,说明了冰相过程在硫沉降中的重要性。  相似文献   

9.
We examine the sensitivities of heterogeneous sulfate chemistry in a mid-latitude and tropical storm using a cloud resolving model. Both thermodynamic environments show unstable conditions favorable for development of intensive convection, with more CAPE in tropical compared to mid-latitude storm. Compared with the observed severe storms, modeled results show a relatively good agreement with the radar and surface chemical observations. Microphysical evaluation indicates that the accretion and autoconversion appear to be most important processes in such considered clouds. This sensitivity simulation is an upper bound for conversion of S (IV) to sulfate. The tropical convective storm produces for about 2.5 times more sulfate compared to mid-latitude storm and converts more SO2 to sulfate, increasing wet deposition of sulfur. The results for a midlatitude run indicate that aerosol nucleation and impact scavenging account for between 18.9% and 28.9% of the in-cloud sulfate ultimately deposited. As a result of greater rainfall efficiency, tropical storm shows about two times higher sub-cloud scavenging rate than mid-latitude storm. The oxidation of S (IV) to SO4 ?2 in cloud droplets and in precipitation is found to be dominant in both convective storms accounting almost with the same percentage contribution of 45.4% and 46.3% to sulfur deposition, respectively. In-cloud oxidation contribute a larger fraction of the total amount of sulfur deposited in tropical case (29.2%) when compared to the mid-latitude case (11.8), respectively. Neglecting aqueous-phase chemistry in ice-phase hydrometeors in both convective clouds led to overpredict deposition of about 40% to 33% relative to the base runs.  相似文献   

10.
Annual wet deposition of excess sulfate at Macquarie Island has been estimated from 5 months of rainwater composition data covering the Austral summer of 1985/86. The resulting figure of 2.1±0.6 mmol/m2/yr is at the low end of previous estimates of maritime excess sulfate deposition by precipitation. Within estimated uncertainty limits this figure is consistent with the DMS emission flux which would be predicted for latitude 50°–60° S, based solely on available Northern Hemispheric DMS measurements.Temporarily at the International Meteorological Institute, Stockholm University, S-106 91, Stockholm, Sweden.  相似文献   

11.
A comparison of large‐scale models simulating atmospheric sulfate aerosols (COSAM) was conducted to increase our understanding of global distributions of sulfate aerosols and precursors. Earlier model comparisons focused on wet deposition measurements and sulfate aerosol concentrations in source regions at the surface. They found that different models simulated the observed sulfate surface concentrations mostly within a factor of two, but that the simulated column burdens and vertical profiles were very different amongst different models. In the COSAM exercise, one aspect is the comparison of sulfate aerosol and precursor gases above the surface. Vertical profiles of SO2, SO2−4, oxidants and cloud properties were measured by aircraft during the North Atlantic Regional Experiment (NARE) experiment in August/September 1993 off the coast of Nova Scotia and during the Second Eulerian Model Evaluation Field Study (EMEFSII), in central Ontario in March/April 1990. While no single model stands out as being best or worst, the general tendency is that those models simulating the full oxidant chemistry tend to agree best with observations although differences in transport and treatment of clouds are important as well.  相似文献   

12.
利用ＳＴＥＭ－ＩＩ三维区域尺度大气化学模式,研究了１９９４年３月１日至１４日东亚地区春季沙尘气溶胶对硫化物输送和沉降的影响。结果表明,ＳＯ２和ＳＯ２４的大值区主要出现在我国东部地区。在模拟时段,日本地区火山源的排放对该地区大气中Ｓ分布的贡献达１０％～３０％。并与当时飞机的观测结果相吻合。模拟区域内ＳＯ２和ＳＯ２４的收支的分析研究表明,在硫的总排放量中,从东边界面流出去的输送通量最大,并出现在３０～４００Ｎ带的２～６ｋｍ高度上,这是与该地区最大的人为排放源所在地相一致的。最后,给出了模拟时段整个对流层大气ＳＯ２－４气溶胶含量的分布,还仨算了ＳＯ２－４气溶胶对地气系统的直接辐射强迫和温度变化的影响。  相似文献   

13.
Throughfall (TF) and wet only (WO) deposition along with SO2 and sulfate (SO42−) concentration in air at 4 urban and rural sites in southwestern China were monitored in order to understand the role of different forms of sulfur (S) emission to the S deposition and its effect in China. The sites were located in Chongqing, Hunan, and Guizhou provinces. S deposition at the most polluted site reached 15 g S m− 2 yr− 1. At three of the sites, located in the vicinity of several emission sources, dry S deposition is 2.1–4.2 times that of wet deposition, which is significantly higher than what is found in most other parts of the world.Main components in airborne particles (PM10) are (NH4)2SO4 and CaSO4 at the highly polluted Tie Shan Ping (TSP) site. Dust particles of gypsum (CaSO4) in the air are partly due to direct emission and partly from the reaction of calcium oxides and carbonates with sulfuric acid in the air. To illustrate the importance of sulfate emission to total S deposition we analyzed the source of S deposition based on both measurements and models. Results indicated that direct emission of SO42− particles could account for high proportion in total S deposition at the three most polluted sites.  相似文献   

14.
We report on results from a World Climate Research Program workshop on representations of scavenging and deposition processes in global transport models of the atmosphere. 15 models were evaluated by comparing simulations of radon, lead, sulfur dioxide, and sulfate against each other, and against observations of these constituents. This paper provides a survey on the simulation differences between models. It identifies circumstances where models are consistent with observations or with each other, and where they differ from observations or with each other. The comparison shows that most models are able to simulate seasonal species concentrations near the surface over continental sites to within a factor of 2 over many regions of the globe. Models tend to agree more closely over source (continental) regions than for remote (polar and oceanic) regions. Model simulations differ most strongly in the upper troposphere for species undergoing wet scavenging processes. There are not a sufficient number of observations to characterize the climatology (long‐term average) of species undergoing wet scavenging in the upper troposphere. This highlights the need for either a different strategy for model evaluation (e.g., comparisons on an event by event basis) or many more observations of a few carefully chosen constituents.  相似文献   

15.
Abstract

The Acid Deposition and Oxidant Model (ADOM) is an Eulerian long‐range transport and deposition model. One of the most highly parametrized and least well established parts of the model is the scavenging module that describes cloud formation, pollutant scavenging, aqueous‐phase chemistry and wet deposition. As a means of gaining insight into the scavenging module, results from simulations with the module are compared with the results from simulations for equivalent conditions with a three‐dimensional dynamic cloud chemistry model.

Comparisons of results for a variety of initial conditions show that wet deposition of sulphate, nitrate and ammonium ions tend to be underpredicted by the scavenging module and that the pH of the rain is overpredicted. Although the differences are for the most part not large, they are sensitive to cloud top height. The amount of hydrogen peroxide deposited at the surface is significantly smaller in the ADOM module than in the cloud chemistry model. For the particular conditions that are considered, oxidation is limited by the hydrogen peroxide concentration for the cloud chemistry model, but by the sulphur dioxide concentration for the ADOM module.  相似文献   

16.
The Asian dust Aerosol Model 2 (ADAM2) with the MM5 meteorological model has been employed to study long-range transport process of Asian dust and to estimate dust emission, deposition (wet and dry) and concentration over the Asian dust source region and the downwind regions for dust events observed in Korea during the period of 20–29 December 2009, which is one of the dust events chosen by the 3rd Meeting of Working Group for Joint Research on Dust Sand Storm among Mongolia, China, Japan and Korea to study intensively for the development of an early warning system in Asia. It is found that the model simulates quite well the starting and ending times of dust events and the peak dust concentrations with their occurrence times both in the source region and downwind regions. The dust emission in the dust source region is found to be associated with a developing synoptic weather system accompanied with strong surface winds over the source region that usually travels east to southeastward across the source region and then turns to move northeastward toward the north western Pacific Ocean. The dust emitted in the source region is found to be split into two parts: one is transported southeastward to the East China Sea in front of the surface high pressure system and experiencing enhanced deposition due to the sinking motion induced by the southeastward traveling the surface high pressure system whereas, the other moves northeastward toward the surface low pressure system and then lifted upward to form a upper-level high dust concentration layer that results in a favorable condition for the long-range transport of dust. It is also found that the maximum ten-day total dust emission of about 23 t km?2 occurs in the domain Northwestern China (NWC). However, the maximum ten-day total dust deposition of 21 t km?2 with the maximum mean surface concentration of 555 μg m?3 and the column integrated mean concentration of 2.9 g m?2 occurs in the domain Central-northern China (CNC). The column-integrated PM10 concentration is found to increase toward northeastward especially in the domain North northeastern China (NNEC) due to the upper-level transported high PM10 concentration. The ten-day total dust deposition, mean surface PM10 and column integrated PM10 concentrations in the downwind domains are found to decrease away from the source region from 2.44 t km?2, 112 μg m?3 and 1.68 g m?2, respectively in the domain YES to 0.06 t km?2, 2.1 μg m?3 and 0.4 g m?2, respectively in the domain Northwestern Pacific 1 (NWP1). Much of the total dust deposition is largely contributed by wet deposition in the far downwind region of the seas while that is contributed by dry deposition in the source region.  相似文献   

17.
Lifetimes, scavenging ratios, andbudgets describe the cycling of atmosphericconstituents and are often used in formulating airpollution control strategies. Most previous studiesof sulfur lifetimes, budgets, and scavenging ratioshave been based on limited observational data or datafrom highly simplified models. The Regional AcidDeposition Model (RADM2.61) shows some skill inpredicting atmospheric mixing ratios of acidicmaterials and other related trace constituents andacid deposition patterns in North America, and so,analysis of its established, theoretical, databaseserves as a counterpoint to previous studies of sulfurbudgets, lifetimes, and scavenging ratios. The annualbudget shows that the net transport (outflow minusinflow) of sulfur compounds out of eastern NorthAmerica is equal to the total deposition within thedomain. Of the total deposition, 63% is from wetdeposition and 37% is from dry deposition. Theannual average lifetime of sulfur dioxide (38 hours),estimated by the turnover time, is limited by aqueousconversion, while that for sulfate aerosols (54 hours)is limited by their removal in precipitation. Theannual average lifetime of sulfur in this domain isslightly more than three days. Episodic lifetimes andbudgets, based on particular synoptic situations, showlarge variations around the annual values. Episodicprecipitation scavenging ratios exhibit similarvariability and are used to offer explanations ofseveral potential biases found in the wet sulfurdeposition amounts as predicted by the EMEP sulfurtransport model and other published results.  相似文献   

18.
An improvement of long-range air pollution transport and diffusion model which includes planetary boundary layer (PBL) dynamics and chemistry of SO2 and NOx, the processes of dry and wet deposition has been developed and used in the Southeast Europe. The transport and diffusion process are described on the basis of a combination of the Eulerian and Lagrangian approaches. A similarity theory is used for calculation of the PBL characteristics. A known linear chemistry module which includes 5 nitrogen and 2 sulphate species is incorporated. The model results for the region of Southeast Europe are in good agreement with the Meteorological Synthesizing Center West, Oslo information.  相似文献   

19.
Total sulfur deposition was determined above a Norway spruce forest, in Hungary. Two methods were applied, on one hand dry + wet deposition measurements and on the other, throughfall and stemflow deposition estimations have been carried out. Results show: total depositions are 3.3 and 3.2 g S m–2 yr–1 determined by dry + wet and throughfall deposition methods, respectively. The share of the dry deposition in the total S-load is 73%. The agreement between the results of the two different methods is good and suggests the needlessness of complicated dry + wet flux measurements, i.e. the total and dry deposition of sulfur compounds to forests can be determined by simple throughfall and wet deposition measurements.  相似文献   

20.
Abstract

The Canadian Atmospheric Environment Service (A ES) Long‐ Range Transport (LRT) model has been used in the Canada‐United States Memorandum of Intent programme to compute transfer matrices in order to quantify the source‐receptor relationships between emission regions and selected receptor sites. Four‐day backward trajectories were computed from the selected sites for the year 1978 and were started from the 925‐mb level(～600 m). The Lagrangian concentration / deposition model computed sulphur concentrations and depositions for 9 receptor sites using an emissions inventory divided into 15 Canadian and25 United States emission regions.

The 40×9 source‐receptor matrices show that the greatest impact on a receptor site usually results from an emission region close to the site although the regions giving the greatest impact for air concentration and wet deposition are not necessarily identical. In addition, the matrices show the impacts of all the emission regions on all of the receptor sites ranked by the magnitudes of the matrix elements. The per cent contribution from each emission region at each receptor site is shown as well as the overall per cent contributions from both Canada and the United States.

These matrices are an attempt to quantify source‐receptor relationships in Canada and the United States for assessing emission control strategies. The uncertainties associated with the matrices are being studied.  相似文献   

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