Evaluation and Intercomparison of Five North American Dry Deposition Algorithms at a Mixed Forest Site

The paper presents an attempt to determine conducting area (CA), relative conducting area (CA.k–1) and mean ring conducting area (CAar) on discs cut at breast height from stems of larch trees growing in fresh mixed coniferous forest and fresh mixed forest sites, representing four age classes and the main crop according to Kraft’s classification. The value of CA increases with an improvement of the social class of tree position in the community, while no such dependences were found for the value of (CA.k–1). The parameter CAar, except for one case in age class IV in the fresh mixed coniferous forest site, increases with an improvement of the position a tree takes in the community and differentiates more markedly under the conditions of fresh mixed forest sites. Relative conducting area (CA.k–1) decreases markedly with an increase in the age of trees, which is confirmed by high values of the coefficient of determination. Moreover, the significance of differences between individual trees in the main crop according to Kraft and forest site types was tested in terms of the values of CAar. Calculated values may be used to describe the relationships between conducting area and the size of the assimilating organ more precisely than the total sapwood zone.

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Changes in Vegetation Condition and Surface Fluxes during NAME 2004

Journal of Climate ◽

10.1175/jcli4088.1 ◽

2007 ◽

Vol 20 (9) ◽

pp. 1810-1820 ◽

Cited By ~ 51

Author(s):

Christopher J. Watts ◽

Russell L. Scott ◽

Jaime Garatuza-Payan ◽

Julio C. Rodriguez ◽

John H. Prueger ◽

...

Keyword(s):

Surface Temperature ◽

Land Surface Temperature ◽

North American ◽

Land Surface ◽

Vegetation Index ◽

Surface Fluxes ◽

North American Monsoon ◽

Forest Site ◽

The North ◽

Dry Spell

Abstract The vegetation in the core region of the North American monsoon (NAM) system changes dramatically after the onset of the summer rains so that large changes may be expected in the surface fluxes of radiation, heat, and moisture. Most of this region lies in the rugged terrain of western Mexico and very few measurements of these fluxes have been made in the past. Surface energy balance measurements were made at seven sites in Sonora, Mexico, and Arizona during the intensive observation period (IOP) of the North American Monsoon Experiment (NAME) in summer 2004 to better understand how land surface vegetation change alters energy flux partitioning. Satellite data were used to obtain time series for vegetation indices and land surface temperature for these sites. The results were analyzed to contrast conditions before the onset of the monsoon with those afterward. As expected, precipitation during the 2004 monsoon was highly variable from site to site, but it fell in greater quantities at the more southern sites. Likewise, large changes in the vegetation index were observed, especially for the subtropical sites in Sonora. However, the changes in the broadband albedo were very small, which was rather surprising. The surface net radiation was consistent with the previous observations, being largest for surfaces that are transpiring and cool, and smallest for surfaces that are dry and hot. The largest evaporation rates were observed for the subtropical forest and riparian vegetation sites. The evaporative fraction for the forest site was highly correlated with its vegetation index, except during the dry spell in August. This period was clearly detected in the land surface temperature data, which rose steadily in this period to a maximum at its end.

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Validation of nitrogen dry deposition modelling above a mixed forest using high-frequency flux measurements

10.5194/egusphere-egu2020-3559 ◽

2020 ◽

Author(s):

Pascal Wintjen ◽

Frederik Schrader ◽

Martijn Schaap ◽

Burkhard Beudert ◽

Christian Brümmer

Keyword(s):

Dry Deposition ◽

High Frequency ◽

Transport Model ◽

Mixed Forest ◽

Reactive Nitrogen ◽

Nitrogen Compounds ◽

Chemical Transport Model ◽

Flux Measurements ◽

Deposition Models

Reactive nitrogen (Nr) compounds comprise essential nutrients for plants. However, a large supply of nitrogen by fertilization through atmospheric deposition may be harmful for ecosystems such as peatlands and may lead to a loss of biodiversity, soil acidification and eutrophication. In addition, nitrogen compounds may cause adverse human health impacts. Large parts of Nr emissions originate from anthropogenic activities. &#160;Emission hotspots of &#931;Nr, i.e. the sum of all Nr compounds, are related to crop production and livestock farming (mainly through ammonia, NH3) and fossil fuel combustion by transport and industry (mainly through nitrogen oxides, NO2 and NO). Such additional amount of Nr will enhance its biosphere-atmosphere exchange, affect plant health and can influence its photosynthetic capacity. Therefore, it is necessary to thoroughly estimate the nitrogen exchange between biosphere and atmosphere.For measuring the nitrogen mixing ratios a converter for reactive nitrogen (TRANC: Total Reactive Atmospheric Nitrogen Converter) was used. The TRANC converts all reactive nitrogen compounds, except for nitrous oxide (N2O), to nitric oxide (NO) and is coupled to a fast-response chemiluminescence detector (CLD). Due to a low detection limit and a response time of about 0.3s the TRANC-CLD system can be used for flux calculation based on the eddy covariance (EC) technique. Flux losses, which are related to the experimental setup, different response characteristics and the general high reactivity of most N gases and aerosols, occur in the high frequency range. We estimated damping factors of approximately 20% with an empirical cospectral approach.For getting a reliable prediction of &#931;Nr fluxes through deposition models, long-term flux measurements offer the possibility to verify the nitrogen uptake capacity and to investigate exchange characteristics of &#931;Nr in different ecosystems.In this study, we compare modelled dry deposition fluxes using the deposition module DEPAC (DEPosition of Acidifying Compounds) within the chemical transport model LOTOS-EUROS (LOng Term Ozone Simulation &#8211; EURopean Operational Smog) against &#931;Nr flux measurements of the TRANC-CLD for a remote mixed forest site with hardly any local anthropogenic emission sources. This procedure allows to determine the background load and the natural exchange characteristics of nitrogen under low atmospheric concentrations. Therefore, the broad-scale dry deposition predicted directly by LOTOS-EUROS was compared to site-specific modelling results obtained using measured meteorological input data as well as the directly measured &#931;Nr fluxes. In addition, the influence of land-use weighting in LOTOS-EUROS was examined. We further compare our results to &#931;Nr deposition estimates obtained with canopy budget techniques. Measured &#931;Nr dry deposition at the site was 4.5 kg N ha-1 yr-1, in close agreement with modelled estimates using DEPAC with measured drivers (5.2 kg N ha-1 yr-1) and as integrated in the chemical transport model LOTOS-EUROS (5.2 kg N ha-1 yr-1 to 6.9 kg N ha-1 yr-1 depending on the weighting of land-use classes).Our study is the first one presenting 2.5 years flux measurements of &#931;Nr above a remote mixed forest. Further verifications of long-term flux measurements against deposition models are useful to improve them and result in better understanding of exchange processes of &#931;Nr.

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Litter and deadwood water retention processes in a temperate mixed forest

10.5194/egusphere-egu21-15217 ◽

2021 ◽

Author(s):

Marius G. Floriancic ◽

Scott T. Allen ◽

Peter Molnar

Keyword(s):

Soil Water ◽

Forest Floor ◽

Water Retention ◽

Storage Capacity ◽

Soil Layer ◽

Mixed Forest ◽

Water Retention Capacity ◽

Forest Site ◽

Retention Capacity ◽

Temperate Mixed Forest

Countless studies have demonstrated ways in which forests and trees affect catchment water balances. Water balance differences between forested and non-forested landscapes are often attributed to characteristics related to trees&#8217; ability to take up and transpire water, as well as their ability to intercept precipitation. However, another potentially important characteristic of forests that has been largely overlooked in hydrologic studies is the retention and accumulation of debris, litter and deadwood on the forest floor. Here we leverage ongoing measurements at the new hillslope laboratory &#8220;Waldlabor&#8221; in Zurich, Switzerland, where water retention in forest litter, deadwood and the top soil layer has been investigated using frequent field campaigns and innovative new sensing techniques.Several approaches were used to determine the maximum storage capacity as well as the storage dynamics of different types and layers of litter. In-lab saturation experiments revealed the maximum storage capacity of various litter types (i.e., leaf and needle litter). Those values were also supported with field pre- and post- rainfall sampling campaigns to determine in-situ litter storage dynamics, as well as to understand the interplay between litter interception and soil-water recharge. Importantly, recharge was often substantially smaller at plots with litter, compared to those without litter. The storage and water retention capacity of deadwood samples was measured in the field by logging the diurnal differences in deadwood weight over a six month period. Dew and fog deposition during the night led to larger water availability for evaporation during the day. We measured increased humidity at sensors in the forest at 1 and 3m heights respectively, compared to the humidity outside the forest. Daily weight measurements over eight weeks of 40 deadwood pieces at our forest site revealed differences in the storage capacity depended on the degree of decomposition. Additionally, we found that water stored in forest floor spruce cones (daily measurements of 20 pieces) actively contributed to evaporation fluxes.The combination of continuous sensor measurements (soil moisture, deadwood water content), field measurements (litter and deadwood grab samples) as well as laboratory work (saturation experiments) revealed the water storage and retention capacity of litter and deadwood in a typical temperate mixed forest and their contribution to evaporation. These measurements are one component of the new ETH Z&#252;rich &#8220;Waldlabor&#8221; research infrastructure, which also includes measurements of precipitation, xylem water, soil water, groundwater, and discharge amounts, isotope ratios, and other chemical characteristics.

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Aerosol dynamics and gas-particle conversion in dry deposition of inorganic reactive nitrogen in a temperate forest

10.5194/acp-2019-703 ◽

2019 ◽

Author(s):

Genki Katata ◽

Kazuhide Matsuda ◽

Atsuyuki Sorimachi ◽

Mizuo Kajino ◽

Kentaro Takagi

Keyword(s):

Dry Deposition ◽

Land Surface ◽

Mixed Forest ◽

Chemical Transport ◽

Reactive Nitrogen ◽

Surface Model ◽

Deposition Flux ◽

Transport Models ◽

Aerosol Dynamics ◽

Chemical Transport Models

Abstract. Although dry deposition has an impact on nitrogen status in the forest environments, the mechanism for high dry deposition rates of fine nitrate aerosols (NO3-) observed in forests remains unknown and is a potential source of error in chemical transport models. Here we developed a new multi-layer land surface model coupled with dry deposition and aerosol dynamics processes for a temperate mixed forest in Japan. The processes of thermodynamics, kinetics, and dry deposition for mixed inorganic aerosols are modeled by a triple-moment modal method. The new model overall reproduces observed turbulent fluxes above the canopy and vertical micrometeorological profiles, as well as inorganic mass and size-resolved total number concentrations within the canopy. Sensitivity tests revealed that the within-canopy evaporation of ammonium nitrate (NH4NO3) under dry conditions significantly enhances deposition flux for fine NO3- and NH4+ aerosols, while reducing deposition flux for nitric acid gas (HNO3). A dry deposition scheme coupled with aerosol dynamics may be required to improve the predictive accuracy of chemical transport models for the surface concentration of inorganic reactive nitrogen.

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Boreal forest BVOC exchange: emissions versus in-canopy sinks

Atmospheric Chemistry and Physics ◽

10.5194/acp-17-14309-2017 ◽

2017 ◽

Vol 17 (23) ◽

pp. 14309-14332 ◽

Cited By ~ 8

Author(s):

Putian Zhou ◽

Laurens Ganzeveld ◽

Ditte Taipale ◽

Üllar Rannik ◽

Pekka Rantala ◽

...

Keyword(s):

Boreal Forest ◽

Dry Deposition ◽

Large Scale ◽

Transport Model ◽

Oxidation Products ◽

Forest Site ◽

Chemical Production ◽

Chemical Transport Model ◽

Understorey Vegetation ◽

Sources And Sinks

Abstract. A multilayer gas dry deposition model has been developed and implemented into a one-dimensional chemical transport model SOSAA (model to Simulate the concentrations of Organic vapours, Sulphuric Acid and Aerosols) to calculate the dry deposition velocities for all the gas species included in the chemistry scheme. The new model was used to analyse in-canopy sources and sinks, including gas emissions, chemical production and loss, dry deposition, and turbulent transport of 12 featured biogenic volatile organic compounds (BVOCs) or groups of BVOCs (e.g. monoterpenes, isoprene+2-methyl-3-buten-2-ol (MBO), sesquiterpenes, and oxidation products of mono- and sesquiterpenes) in July 2010 at the boreal forest site SMEAR II (Station for Measuring Ecosystem–Atmosphere Relations). According to the significance of modelled monthly-averaged individual source and sink terms inside the canopy, the selected BVOCs were classified into five categories: 1. Most of emitted gases are transported out of the canopy (monoterpenes, isoprene + MBO). 2. Chemical reactions remove a significant portion of emitted gases (sesquiterpenes). 3. Bidirectional fluxes occur since both emission and dry deposition are crucial for the in-canopy concentration tendency (acetaldehyde, methanol, acetone, formaldehyde). 4. Gases removed by deposition inside the canopy are compensated for by the gases transported from above the canopy (acetol, pinic acid, β-caryophyllene's oxidation product BCSOZOH). 5. The chemical production is comparable to the sink by deposition (isoprene's oxidation products ISOP34OOH and ISOP34NO3). Most of the simulated sources and sinks were located above about 0.2 hc (canopy height) for oxidation products and above about 0.4 hc for emitted species except formaldehyde. In addition, soil deposition (including deposition onto understorey vegetation) contributed 11–61 % to the overall in-canopy deposition. The emission sources peaked at about 0.8–0.9 hc, which was higher than 0.6 hc where the maximum of dry deposition onto overstorey vegetation was located. This study provided a method to enable the quantification of the exchange between atmosphere and biosphere for numerous BVOCs, which could be applied in large-scale models in future. With this more explicit canopy exchange modelling system, this study analysed both the temporal and spatial variations in individual in-canopy sources and sinks, as well as their combined effects on driving BVOC exchange. In this study 12 featured BVOCs or BVOC groups were analysed. Other compounds could also be investigated similarly by being classified into these five categories.

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Dry deposition of O 3 and SO 2 estimated from gradient measurements above a temperate mixed forest

Environmental Pollution ◽

10.1016/j.envpol.2015.11.052 ◽

2016 ◽

Vol 210 ◽

pp. 202-210 ◽

Cited By ~ 8

Author(s):

Zhiyong Wu ◽

Ralf Staebler ◽

Robert Vet ◽

Leiming Zhang

Keyword(s):

Dry Deposition ◽

Mixed Forest ◽

Temperate Mixed Forest ◽

Gradient Measurements

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Boreal forest BVOCs exchange: emissions versus in-canopy sinks

10.5194/acp-2017-493 ◽

2017 ◽

Cited By ~ 1

Author(s):

Putian Zhou ◽

Laurens Ganzeveld ◽

Ditte Taipale ◽

Üllar Rannik ◽

Pekka Rantala ◽

...

Keyword(s):

Boreal Forest ◽

Dry Deposition ◽

Large Scale ◽

Transport Model ◽

Oxidation Products ◽

Forest Site ◽

Chemical Production ◽

Chemical Transport Model ◽

Canopy Exchange ◽

Sources And Sinks

Abstract. A multi-layer gas dry deposition model has been developed and implemented into a 1-dimensional chemical transport model SOSAA (a model to Simulate the concentrations of Organic vapours, Sulphuric Acid and Aerosols) to calculate the dry deposition velocities for all the gas species included in the chemistry scheme. The new model was used to analyse in-canopy sources and sinks, including gas emissions, chemical production and loss, dry deposition and turbulent transport of 12 featured biogenic volatile organic compounds (BVOCs) or groups of BVOCs (e.g., monoterpenes, isoprene&plus;2-methyl-3-buten-2-ol (MBO), sesquiterpenes and oxidation products of mono- and sesquiterpenes) in July, 2010 at the boreal forest site SMEAR II (Station to Measure Ecosystem-Atmosphere Relations II). According to the significance of modeled monthly averaged individual source and sink terms inside the canopy, the selected BVOCs were classified into five categories: (1) most of emitted gases are transported out of the canopy (monoterpenes, isoprene&plus;MBO), (2) chemical reactions remove a significant portion of emitted gases (sesquiterpenes), (3) bidirectional fluxes occur since both emission and dry deposition are crucial for the in-canopy concentration tendency (acetaldehyde, methanol, acetone, formaldehyde), (4) gases removed by deposition inside the canopy are compensated by the gases transported from above the canopy (acetol, pinic acid, β-caryophyllene's oxidation product BCSOZOH), and finally (5) the chemical production is comparable to the sink by deposition (isoprene's oxidation products ISOP34OOH and ISOP34NO3). Most of the simulated sources and sinks were located above about 4 m for oxidation products and above about 8 m for emitted species except formaldehyde. In addition, soil deposition (including deposition onto understory vegetation) contributed 11–61 % to the overall in-canopy deposition. The emission sources peaked at about 14–16 m which was higher than 10 m where the maximum of dry deposition onto overstorey vegetation was located. This study provided a method to enable the quantification of the exchange between atmosphere and biosphere for numerous BVOCs, which could be applied in large-scale models in future. With this more explicit canopy exchange modeling system this study analysed both the temporal and spatial variations of individual in-caonpy sources and sinks, as well as their combined effects on driving BVOCs exchange. Twelve featured BVOCs or BVOC groups were analyzed in this study, more compounds could also be investigated similarly by being classified into the five categories.

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Extension of a gaseous dry deposition algorithm to oxidized volatile organic compounds and hydrogen cyanide for application in chemistry transport models

10.5194/gmd-2021-41 ◽

2021 ◽

Author(s):

Zhiyong Wu ◽

Leiming Zhang ◽

John T. Walker ◽

Paul A. Makar ◽

Judith A. Perlinger ◽

...

Keyword(s):

Volatile Organic Compounds ◽

Organic Compounds ◽

Dry Deposition ◽

Hydrogen Cyanide ◽

Deposition Velocity ◽

Mixed Forest ◽

Chemical Species ◽

Flux Divergence ◽

Diel Cycles ◽

Volatile Organic

Abstract. With increasing complexity of air quality models, additional chemical species have been included in model simulations for which dry deposition processes need to be parameterized. For this purpose, the gaseous dry deposition scheme of Zhang et al. (2003) is extended to include 12 oxidized volatile organic compounds (oVOCs) and hydrogen cyanide (HCN) based on their physicochemical properties, namely the effective Henry's law constants and oxidizing capacities. Modeled dry deposition velocity (Vd) values are compared against field flux measurements over a mixed forest in the southeastern U.S. during June 2013. The model captures the basic features of the diel cycles of the observed Vd. Modeled Vd values are comparable to the measurements for most of the oVOCs at night. However, modeled Vd values are mostly around 1 cm s−1 during daytime, which is much smaller than the observed daytime maxima of 2–5 cm s−1. Analysis of the individual resistance terms/uptake pathways suggests that flux divergence due to fast atmospheric chemical reactions near the canopy was likely the main cause of the large model-measurement discrepancies during daytime. The extended dry deposition scheme likely provides conservative Vd values for many oVOCs. While higher Vd values and bi-directional fluxes can be simulated by coupling key atmospheric chemical processes into the dry deposition scheme, we suggest that more experimental evidence of high oVOC Vd values at additional sites is required to confirm the broader applicability of the high values studied here. The underlying processes leading to high measured oVOC Vd values require further investigation.

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