scholarly journals Elemental carbon in snow at Changbai Mountain, Northeastern China: concentrations, scavenging ratios and dry deposition velocities

2013 ◽  
Vol 13 (5) ◽  
pp. 14221-14248 ◽  
Author(s):  
Z. W. Wang ◽  
C. A. Pedersen ◽  
X. S. Zhang ◽  
J. C. Gallet ◽  
J. Ström ◽  
...  
Keyword(s):  
Dry Deposition ◽  
Elemental Carbon ◽  
Deposition Velocity ◽  
Northeastern China ◽  
Changbai Mountain ◽  
Deposition Flux ◽  
Upper Limit ◽  
The Mean ◽  
Scavenging Ratio ◽  
Scavenging Ratios

Abstract. Light absorbing aerosol, in particular elemental carbon (EC), in snow and ice enhance absorption of solar radiation, reduce the albedo, and is an important climate driver. In this study, measurements of EC concentration in air and snow are performed concurrently at Changbai Station, Northeastern China, from 2009 to 2012. The mean EC concentration for surface snow is 987 ± 1510 ng g−1 with a range of 7 to 7636 ng g−1. EC levels in surface snow around (about 50 km) Changbai Mountain are lower than those collected on the same day at Changbai station, and decrease with distance from Changbai station, indicating that EC load in snow around Changbai Mountain is influenced by local source emissions. Scavenging ratios of EC by snow are calculated through comparing the concentrations of EC in fresh snow with those in air. The upper-limit of mean scavenging ratio is 137.4 ± 99.7 with median 149.4, which is smaller than those reported from Arctic areas. The non-rimed snow process may be one of significant factors for interpreting the difference of scavenging ratio in this area with the Arctic areas. Finally, wet and dry depositional fluxes of EC have been estimated, and the upper-limit of EC wet deposition flux is 0.46 ± 0.38 μg cm−2 month−1 during the three consecutive snow season, and 1.32 ± 0.95 μg cm−2 month−1 for dry deposition flux from December to February during study period. During these three years, 77% of EC in snow is attributed to the dry deposition, indicating that dry deposition processes play a major role for EC load in snow in the area of Changbai, Northeastern China. Based on the dry deposition fluxes of EC and hourly black carbon (BC) concentrations in air, the estimated mean dry deposition velocity is 2.81 × 10−3 m s−1 with the mean median of 3.15 × 10−3 m s−1. These preliminary estimates for the scavenging ratio and dry deposition velocity of EC on snow surface will be beneficial for numerical models, and improve simulations of EC transport, fate and radiative forcing in order to ultimately make better climate prediction.

scholarly journals Elemental carbon in snow at Changbai Mountain, northeastern China: concentrations, scavenging ratios, and dry deposition velocities

2014 ◽  
Vol 14 (2) ◽  
pp. 629-640 ◽  
Author(s):  
Z. W. Wang ◽  
J. C. Gallet ◽  
C. A. Pedersen ◽  
X. S. Zhang ◽  
J. Ström ◽  
...  
Keyword(s):  
Dry Deposition ◽  
Wet Deposition ◽  
Radiative Forcing ◽  
Elemental Carbon ◽  
Northeastern China ◽  
Snow Surface ◽  
Deposition Fluxes ◽  
The Mean ◽  
Deposition Processes ◽  
Scavenging Ratio

Abstract. Light-absorbing aerosol – particularly elemental carbon (EC) – while mixed with snow and ice is an important climate driver from the enhanced absorption of solar radiation. Currently, considerable efforts are being made to estimate its radiative forcing on a global scale, but several uncertainties remain, particularly those regarding its deposition processes. In this study, concurrent measurements of EC in air and snow are performed for three years (2009–2012) at Changbai station, northeastern China. The scavenging ratio and the wet- and dry-deposition fluxes of EC over the snow surface are estimated. The mean EC concentration in the surface snow is 1000 ± 1500 ng g−1, ranging from 7 to 7640 ng g−1. The mean value of the scavenging ratio of EC by snow is 140 ± 100, with a median value of 150, which is smaller than that reported in Arctic areas. A non-rimed snow process is a significant factor in interpreting differences with Arctic areas. Wet-deposition fluxes of EC are estimated to be 0.47 ± 0.37 μg cm−2 month−1 on average over the three snow seasons studied. Dry deposition is more than five times higher, with an average of 2.65 ± 1.93 μg cm−2 month−1; however, only winter period estimation is possible (December–February). During winter in Changbai, 87% of EC in snow is estimated to be due to dry deposition, with a mean dry deposition velocity of 6.44 × 10−3 m s−1 and median of 8.14 × 10−3 m s−1. Finally, the calculation of the radiative effect shows that 500 ng g−1 of dry-deposited EC to a snow surface absorbs three times more incoming solar energy than the same mass mixed in the snow through wet deposition. Deposition processes of an EC-containing snow surface are, therefore, crucial to estimate its radiative forcing better, particularly in northeastern China, where local emission strongly influences the level and gradient of EC in the snowpack, and snow-covered areas are cold and dry due to the atmospheric general circulation. Furthermore, this study builds on the knowledge to characterize the conditions in the snow-laden Chinese rural areas better as well as to constrain transport of EC to the Arctic better.

scholarly journals How are NH<sub>3</sub> dry deposition estimates affected by combining the LOTOS-EUROS model with IASI-NH<sub>3</sub> satellite observations?

2018 ◽  
Author(s):  
Shelley C. van der Graaf ◽  
Enrico Dammers ◽  
Martijn Schaap ◽  
Jan Willem Erisman
Keyword(s):  
Dry Deposition ◽  
Transport Model ◽  
Atmospheric Transport ◽  
Deposition Velocity ◽  
Deposition Flux ◽  
Deposition Fluxes ◽  
Po Valley ◽  
Atmospheric Remote Sensing ◽  
Spatial Coverage ◽  
Recent Developments

Abstract. Atmospheric levels of reactive nitrogen have substantially increased during the last century resulting in increased nitrogen deposition to ecosystems, causing harmful effects such as soil acidification, reduction in plant biodiversity and eutrophication in lakes and the ocean. Recent developments in the use of atmospheric remote sensing enabled us to resolve concentration fields of NH3 with larger spatial coverage and these observations may be used to improve the quantification of NH3 deposition. In this paper we use a relatively simple, data-driven method to derive dry deposition fluxes and surface concentrations of NH3 for Europe and for the Netherlands. The aim of this paper is to determine for the applicability and the limitations of this method for NH3 using space-born observations of the Infrared Atmospheric Sounding Interferometer (IASI) and the LOTOS-EUROS atmospheric transport model. The original modelled dry NH3 deposition flux from LOTOS-EUROS and the flux inferred from IASI are compared to indicate areas with large discrepancies between the two and where potential model improvements are needed. The largest differences in derived dry deposition fluxes occur in large parts of Central Europe, where the satellite-observed NH3 concentrations are higher than the modelled ones, and in Switzerland, northern Italy (Po Valley) and southern Turkey, where the modelled NH3 concentrations are higher than the satellite-observed ones. A sensitivity analysis of 8 model input parameters important for NH3 dry deposition modelling showed that the IASI-derived dry NH3 deposition fluxes may vary from ~ 20 % up to ~ 50 % throughout Europe. Variations in the dry deposition velocity used for NH3 led to the largest deviations in the IASI-derived dry NH3 deposition flux and should be focused on in the future. A comparison of NH3 surface concentrations with in-situ measurements of several established networks (EMEP, MAN and LML) showed no significant, or consistent improvement in the IASI-derived NH3 surface concentrations compared to the originally modelled NH3 surface concentrations from LOTOS-EUROS. It is concluded that the IASI-derived NH3 deposition fluxes do not show strong improvements compared to modelled NH3 deposition fluxes and there is future need for better, more robust, methods to derive NH3 dry deposition fluxes.

scholarly journals Technical note: How are NH<sub>3</sub> dry deposition estimates affected by combining the LOTOS-EUROS model with IASI-NH<sub>3</sub> satellite observations?

2018 ◽  
Vol 18 (17) ◽  
pp. 13173-13196 ◽  
Author(s):  
Shelley C. van der Graaf ◽  
Enrico Dammers ◽  
Martijn Schaap ◽  
Jan Willem Erisman
Keyword(s):  
Dry Deposition ◽  
Transport Model ◽  
Atmospheric Transport ◽  
Deposition Velocity ◽  
Monitoring And Evaluation ◽  
Technical Note ◽  
Deposition Flux ◽  
Deposition Fluxes ◽  
Po Valley ◽  
Spatial Coverage

Abstract. Atmospheric levels of reactive nitrogen have increased substantially during the last century resulting in increased nitrogen deposition to ecosystems, causing harmful effects such as soil acidification, reduction in plant biodiversity and eutrophication in lakes and the ocean. Recent developments in the use of atmospheric remote sensing enabled us to resolve concentration fields of NH3 with larger spatial coverage. These observations may be used to improve the quantification of NH3 deposition. In this paper, we use a relatively simple, data-driven method to derive dry deposition fluxes and surface concentrations of NH3 for Europe and for the Netherlands. The aim of this paper is to determine the applicability and the limitations of this method for NH3. Space-born observations of the Infrared Atmospheric Sounding Interferometer (IASI) and the LOTOS-EUROS atmospheric transport model are used. The original modelled dry NH3 deposition flux from LOTOS-EUROS and the flux inferred from IASI are compared to indicate areas with large discrepancies between the two. In these areas, potential model or emission improvements are needed. The largest differences in derived dry deposition fluxes occur in large parts of central Europe, where the satellite-observed NH3 concentrations are higher than the modelled ones, and in Switzerland, northern Italy (Po Valley) and southern Turkey, where the modelled NH3 concentrations are higher than the satellite-observed ones. A sensitivity analysis of eight model input parameters important for NH3 dry deposition modelling showed that the IASI-derived dry NH3 deposition fluxes may vary from ∼ 20 % up to ∼50 % throughout Europe. Variations in the NH3 dry deposition velocity led to the largest deviations in the IASI-derived dry NH3 deposition flux and should be focused on in the future. A comparison of NH3 surface concentrations with in situ measurements of several established networks – the European Monitoring and Evaluation Programme (EMEP), Meetnet Ammoniak in Natuurgebieden (MAN) and Landelijk Meetnet Luchtkwaliteit (LML) – showed no significant or consistent improvement in the IASI-derived NH3 surface concentrations compared to the originally modelled NH3 surface concentrations from LOTOS-EUROS. It is concluded that the IASI-derived NH3 deposition fluxes do not show strong improvements compared to modelled NH3 deposition fluxes and there is a future need for better, more robust, methods to derive NH3 dry deposition fluxes.

Aerosol acidity as a driver of aerosol formation and nutrient deposition to ecosystems

2020 ◽  
Author(s):  
Athanasios Nenes ◽  
Maria Kanakidou ◽  
Spyros Pandis ◽  
Armistead Russell ◽  
Shaojie Song ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Particulate Matter ◽  
Dry Deposition ◽  
Deposition Velocity ◽  
Liquid Water Content ◽  
Reactive Nitrogen ◽  
Deposition Flux ◽  
Deposition Rates ◽  
Dry Deposition Flux ◽  
Nitrate Aerosol

&lt;p&gt;Nitrogen oxides (NOx) and ammonia (NH&lt;sub&gt;3&lt;/sub&gt;) from anthropogenic and biogenic emissions are central contributors to particulate matter (PM) concentrations worldwide. Ecosystem productivity can also be strongly modulated by the atmospheric deposition of this inorganic &quot;reactive nitrogen&quot; nutrient. The response of PM and nitrogen deposition to changes in the emissions of both compounds is typically studied on a case-by-case basis, owing in part to the complex thermodynamic interactions of these aerosol precursors with other PM constituents. In the absence of rain, much of the complexity of nitrogen deposition is driven by the large difference in dry deposition velocity when a nitrogen-containing molecule is in the gas or condensed phase.&lt;/p&gt;&lt;p&gt;Here we present a simple but thermodynamically consistent approach that expresses the chemical domains of sensitivity of aerosol particulate matter to NH&lt;sub&gt;3&lt;/sub&gt; and HNO&lt;sub&gt;3&lt;/sub&gt; availability in terms of aerosol pH and liquid water content. From our analysis, four policy-relevant regimes emerge in terms of sensitivity: i) NH&lt;sub&gt;3&lt;/sub&gt;-sensitive, ii) HNO&lt;sub&gt;3&lt;/sub&gt;-sensitive, iii) combined NH&lt;sub&gt;3&lt;/sub&gt; and HNO&lt;sub&gt;3&lt;/sub&gt; sensitive, and, iv) a domain where neither NH&lt;sub&gt;3&lt;/sub&gt; and HNO&lt;sub&gt;3&lt;/sub&gt; are important for PM levels (but only nonvolatile precursors such as NVCs and sulfate). When this framework is applied to ambient measurements or predictions of PM and gaseous precursors, the &amp;#8220;chemical regime&amp;#8221; of PM sensitivity to NH3 and HNO3 availability is directly determined.&amp;#160;&lt;/p&gt;&lt;p&gt;The same framework is then extended to consider the impact of gas-to-particle partitioning, on the deposition velocity of NH&lt;sub&gt;3&lt;/sub&gt; and HNO&lt;sub&gt;3&lt;/sub&gt; individually, and combined affects the dry deposition of inorganic reactive nitrogen. Four regimes of deposition velocity emerge: i) HNO&lt;sub&gt;3&lt;/sub&gt;-fast, NH&lt;sub&gt;3&lt;/sub&gt;-slow, ii) HNO&lt;sub&gt;3&lt;/sub&gt;-slow, NH&lt;sub&gt;3&lt;/sub&gt;-fast, iii) HNO&lt;sub&gt;3&lt;/sub&gt;-fast, NH&lt;sub&gt;3&lt;/sub&gt;-fast, and, iv) HNO&lt;sub&gt;3&lt;/sub&gt;-slow, NH&lt;sub&gt;3&lt;/sub&gt;-slow. Conditions that favor strong partitioning of species to the aerosol phase strongly delay the deposition of reactive nitrogen species and promotes their accumulation in the boundary layer and potential for long-range transport.&amp;#160;&lt;/p&gt;&lt;p&gt;The use of these regimes allows novel insights and is an important tool to evaluate chemical transport models. Most notably, we find that nitric acid displays considerable variability of dry deposition flux, with maximum deposition rates found in the Eastern US (close to gas-deposition rates) and minimum rates for North Europe and China. Strong reductions in deposition velocity lead to considerable accumulation of nitrate aerosol in the boundary layer &amp;#8211;up to 10-fold increases in PM2.5 nitrate aerosol, eventually being an important contributor to high PM2.5 levels observed during haze episodes. With this new understanding, aerosol pH and associated liquid water content can be understood as control parameters that drive PM formation and dry deposition flux and arguably can catalyze the accumulation of aerosol precursors that cause intense haze events throughout the globe.&lt;/p&gt;

scholarly journals A synthesis review on atmospheric wet deposition of particulate elements: scavenging ratios, solubility and flux measurements

2021 ◽  
Author(s):  
Irene Cheng ◽  
Abdulla Al Mamun ◽  
Leiming Zhang
Keyword(s):  
Middle East ◽  
Wet Deposition ◽  
Ambient Air ◽  
Deposition Flux ◽  
Regression Equations ◽  
Specific Element ◽  
Deposition Fluxes ◽  
Flux Measurements ◽  
Scavenging Ratio ◽  
Scavenging Ratios

Atmospheric dry and wet deposition of particulate matter controls its lifetime in air and contributes to the environmental burden of toxic pollutants, and thus has important implications on human and ecosystem health. This synthesis review focused on atmospheric wet deposition of particulate elements and analyzed their scavenging ratios (i.e. concentration in precipitation to that in ambient air), solubility and wet deposition flux measurements based on published studies in literature, aiming to gather updated knowledge that can be used for modeling their wet deposition. Our analysis finds that scavenging ratios of a specific element have a narrow range. Overall, elemental scavenging ratios for snow are ~3 times higher than those for rain. Elements that are bound to coarse (PM2.5-10) particles have larger scavenging ratios than those bound to fine (PM2.5) particles except for Fe and Si. Solubility of elements in rainwater range from 8% (Fe) to 94% (Ca). Solubility is moderately correlated with scavenging ratio possibly explaining the lower scavenging ratios of Fe and Si compared to other elements with similar fine fraction. Data collected from North America, Europe, the Middle East, and Asia show that the wet fluxes of Al and Fe are orders of magnitude greater than those of routinely-monitored anthropogenic elements (Zn, Pb, Cu, Ni, Cd, Cr). Wet deposition fluxes of particulate elements in the Middle East exceed those in other regions, likely due to regional transport of dust and soil resuspension. Fluxes from all regions are a factor of 2-3 greater in industrialized and urban locations than rural and remote locations because of industrial, vehicular and soil and mineral dust emissions. Dry deposition fluxes are usually greater than wet deposition fluxes although to varying degrees according to co-located measurements. Based on the relationships between scavenging ratio and elemental PM2.5 fraction under rain and snow conditions, we derived regression equations for estimating scavenging ratios of particulate elements whose measurements are limited. Such knowledge and data improves the quantification of atmospheric deposition fluxes for an expanded list of metals and metalloids and the understanding of pathways contributing to ecological risk.

scholarly journals Aerosol acidity and liquid water content regulate the dry deposition of inorganic reactive nitrogen

2021 ◽  
Vol 21 (8) ◽  
pp. 6023-6033
Author(s):  
Athanasios Nenes ◽  
Spyros N. Pandis ◽  
Maria Kanakidou ◽  
Armistead G. Russell ◽  
Shaojie Song ◽  
...  
Keyword(s):  
Water Content ◽  
Liquid Water ◽  
Dry Deposition ◽  
Deposition Velocity ◽  
Liquid Water Content ◽  
Reactive Nitrogen ◽  
Deposition Flux ◽  
Eastern United States ◽  
Total Ammonia ◽  
The Individual

Abstract. Ecosystem productivity is strongly modulated by the atmospheric deposition of inorganic reactive nitrogen (the sum of ammonium and nitrate). The individual contributions of ammonium and nitrate vary considerably over space and time, giving rise to complex patterns of nitrogen deposition. In the absence of rain, much of this complexity is driven by the large difference between the dry deposition velocity of nitrogen-containing molecules in the gas or condensed phase. Here we quantify how aerosol liquid water and acidity, through their impact on gas–particle partitioning, modulate the deposition velocity of total NH3 and total HNO3 individually while simultaneously affecting the dry deposition of inorganic reactive nitrogen. Four regimes of deposition velocity emerge: (i) HNO3 – fast, NH3 – slow, (ii) HNO3 – slow, NH3 – fast, (iii) HNO3 – fast, NH3 – fast, and (iv) HNO3 – slow, NH3 – slow. Conditions that favor partitioning of species to the aerosol phase strongly reduce the local deposition of reactive nitrogen species and promote their accumulation in the boundary layer and potential for long-range transport. Application of this framework to select locations around the world reveals fundamentally important insights: the dry deposition of total ammonia displays little sensitivity to pH and liquid water variations, except under conditions of extreme acidity and/or low aerosol liquid water content. The dry deposition of total nitric acid, on the other hand, is quite variable, with maximum deposition velocities (close to gas deposition rates) found in the eastern United States and minimum velocities in northern Europe and China. In the latter case, the low deposition velocity leads to up to 10-fold increases in PM2.5 nitrate aerosol, thus contributing to the high PM2.5 levels observed during haze episodes. In this light, aerosol pH and associated liquid water content can be considered to be control parameters that drive dry deposition flux and can accelerate the accumulation of aerosol contributing to intense haze events throughout the globe.

scholarly journals A new parameterization of particle dry deposition over rough surfaces

2014 ◽  
Vol 14 (22) ◽  
pp. 12429-12440 ◽  
Author(s):  
J. Zhang ◽  
Y. Shao
Keyword(s):  
Dry Deposition ◽  
Particle Deposition ◽  
Rough Surfaces ◽  
Deposition Velocity ◽  
Deposition Flux ◽  
Data Set ◽  
Roughness Elements ◽  
Drag Partition ◽  
Wind Tunnel Data ◽  
Surface Particle

Abstract. In existing particle dry deposition schemes, the effects of gravity and surface roughness elements on particle motion are often poorly represented. In this study, we propose a new scheme to overcome such deficiencies. Particle deposition velocity is a function of aerodynamic, surface-collection and gravitational resistances. In this study, the effect of gravitation settling is treated analytically. More importantly, the new scheme takes into consideration the impacts of roughness elements on turbulent particle diffusion and surface particle collection. A relationship between aerodynamic and surface-collection processes is established by using an analogy between drag partition and deposition-flux partition. The scheme is then tested against a wind-tunnel data set for four different surfaces and a good agreement between the scheme predictions and the observations is found. The sensitivity of the scheme to the input parameters is tested. Important factors which affect particle deposition in different particle size ranges are identified. The scheme shows good capacity for modeling particle deposition over rough surfaces.

scholarly journals Aerosol acidity and liquid water content regulate the dry deposition of inorganic reactive nitrogen

2020 ◽  
Author(s):  
Athanasios Nenes ◽  
Spyros N. Pandis ◽  
Maria Kanakidou ◽  
Armistead Russell ◽  
Shaojie Song ◽  
...  
Keyword(s):  
Water Content ◽  
Liquid Water ◽  
Dry Deposition ◽  
Deposition Velocity ◽  
Liquid Water Content ◽  
Reactive Nitrogen ◽  
Deposition Flux ◽  
Total Ammonia ◽  
Individual Contributions ◽  
The Individual

Abstract. Ecosystem productivity is strongly modulated by the atmospheric deposition of inorganic reactive nitrogen (the sum of ammonium and nitrate). The individual contributions of ammonium and nitrate vary considerably over space and time, giving rise to complex patterns of nitrogen deposition. In the absence of rain, much of this complexity is driven by the large difference between the dry deposition velocity of nitrogen-containing molecules in the gas or condensed phase. Here we quantify how aerosol liquid water and acidity, through their impact on gas-to-particle partitioning, modulate the deposition velocity of NH3 and HNO3 individually, while simultaneously affecting the dry deposition of inorganic reactive nitrogen. Four regimes of deposition velocity emerge: i) HNO3-fast, NH3-slow, ii) HNO3-slow, NH3-fast, iii) HNO3-fast, NH3-fast, and, iv) HNO3-slow, NH3-slow. Conditions that favor partitioning of species to the aerosol phase strongly reduce the deposition of reactive nitrogen species and promote their accumulation in the boundary layer and potential for long-range transport. Application of this framework to select locations around the world reveals fundamentally important insights: The dry deposition of total ammonia displays little sensitivity to pH and liquid water variations, except under conditions of extreme acidity and/or low aerosol liquid water content. The dry deposition of total nitric acid, on the other hand, is quite variable, with maximum deposition velocities (close to gas-deposition rates) found in the Eastern US and minimum velocities in Northern Europe and China. In the latter case, the low deposition velocity leads to up to 10-fold increases in PM2.5 nitrate aerosol, thus contributing to the high PM2.5 levels observed during haze episodes. In this light, aerosol pH and associated liquid water content can be considered as control parameters that drive dry deposition flux and can accelerate the accumulation of aerosol contributing to intense haze events throughout the globe.

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