5th iLEAPS Science Conference Abstracts - B3

Abstracts – Session B3

Canopy Processes and Deposition

B301ORAL-0046: Uncertainty associated with representations of stomatal conductance in CLM4.5

Danica Lombardozzi1, Gordon Bonan1, Peter Franks2, David Lawrence1

1National Center for Atmospheric Research, Boulder, CO, The United States of America 2University of Sydney, Sydney, Australia

Stomatal conductance is the primary control regulating fluxes between the plant canopy and the atmosphere. Despite the importance of stomata in regulating several ecosystem processes, considerable uncertainty exists in how large-scale models represent stomatal conductance. Here, we test two different representations of stomatal conductance that are based on similar physiological foundations: the commonly-used Ball-Berry model and the newer Medlyn model.  We include each stomatal conductance model in the Community Land Model version 4.5 (CLM4.5) to determine the magnitude of structural uncertainty as well as the impacts on associated ecosystem processes, including gross primary productivity, hydrology, and deposition of atmospheric pollutants like nitrogen and ozone. Stomatal conductance varies up to 50% between the two models, though differences are smaller if comparable slope values are used in both stomatal conductance representations. The differences also change transpiration, gross primary productivity, and total surface runoff in some regions. Results suggest that both the Ball-Berry and the Medlyn models are valid methods to use in large-scale land-surface models, though may cause differences in productivity, hydrology, and deposition.

B302 ORAL-0055: Moss indicating atmospheric pollution across different spatial scales

Winfried Schröder1, Stefan Nickel1

1Chair of Landscape Ecology, University of Vechta, Vechta, Germany

Monitoring of atmospheric deposition can be achieved by chemical transport modelling, by collecting deposition with technical samplers and by using bioindicators such as lichens, needles / leaves, soils or moss. Within the European Moss Survey (EMS), sampling of moss at up to 7300 sites across Europe, chemical analysis of heavy metals (HM, since 1990), of nitrogen (N, since 2005) and of persistent organic pollutants (POPs, since 2010) in moss as well as quality control and statistical evaluation were conducted according to a harmonized methodology every five years 1990-2015. In Germany, in addition to the results from chemical analysis, information on characteristics of the sampling sites (e.g., canopy drip) and their surroundings which could influence the HM concentration in moss is collected and integrated into a geographic information system for statistical analysis including, e.g., the calculation of minimum sample size needed for reliable statistics, geostatistics and decision trees analysis.
 
The results proved that the EMS allows reliable statistics for HM and N across the European territory, single participating countries as well as for several ecological land classes covering Europe. Geostatistics enabled mapping spatial patterns from measurements, i.e. to fill up the space between the measurement sites. The correlations indicated that moss fairly well indicate atmospheric deposition and, therefore, should be used to enhance the spatial resolution of deposition maps and, subsequently, deposition and critical loads maps. The indicative power of moss data was compared with results yielded both with other biomonitors and chemical transport modelling [1-5].
 
References: [1] Nickel S et al. Atmos Environ 2017, 156:146-159. [2] Nickel S, Schröder W. Environ Sci Pollut Res 2017, 24:11919-11939 [3] Nickel S, Schröder W. Ecological Indic 2017, 76:194-206. [4] Schröder W et al. Environ Sci Pollut Res 2016, 23:10457-10476. [5] Schröder W et al. Ann For Sci 2017, 74, 31:1-23.

B303ORAL-0026: A study on air-surface interaction of atmospheric gases and particles over Indo-Gangetic basinA study on air-surface interaction of atmospheric gases and particles over Indo-Gangetic basin

Ranjit Kumar1, Pratima Gupta2, Ashok Jangid3

1Department of Chemistry, Faculty of science, Dayalbagh Educational Institute (Deemed University), Agra, India 2Department of Chemistry, Faculty of science, Dayalbagh Educational Institute (Deemed University), , Agra, India 3Department of Physics and Computer Science, Faculty of science, Dayalbagh Educational Institute (Deemed University), , Agra, India

The earth’s surface is a sink for atmospheric trace gases and particles. Atmospheric gases and particles reach to earth systems. They exchange and interact with the receptor. Dry deposition is an important mechanism of transfer of atmospheric particles and gases from the atmosphere and deposited directly onto or into natural surfaces / vegetation. The deposition flux depends upon the chemical constituents of particles /gases as well as on chemical properties of depositing surfaces. Hence, the present study describes the understanding on deposition and the exchange of trace gases and aerosols between the earth’s surface (vegetation) and the atmosphere. The continuous measurement of particle concentration, dry deposition flux and dry deposition velocity of major anions and cations has been carried out in Agra over the Indo-Gangetic basin. The mean dry deposition flux on natural surface was highest for calcium and lowest for fluoride. It may due to high concentration of calcium and it high mass median diameter. The average dry deposition velocity of major cation and anion were found to be in the range of 0.05 to 2.7 cm s-1. The seasonal variation of dry deposition fluxes were highest in winter followed by summer and monsoon. The annual input of sulphur and nitrogen containing are in the reported range.  

B304ORAL-0213: Interannual variability in ozone dry deposition at a temperate deciduous forest

Olivia Clifton, Arlene Fiore, J. W. Munger, Sergey Malyshev, Larry Horowitz, Elena Shevliakova, Fabien Paulot, Lee Murray, Kevin Griffin

The ozone dry depositional sink and its contribution to observed variability in tropospheric ozone are both poorly understood. Distinguishing ozone uptake through plant stomata versus other pathways is relevant for quantifying the ozone influence on carbon and water cycles. We use a decade of ozone, carbon, and energy eddy covariance fluxes at Harvard Forest to investigate interannual variability in ozone deposition velocities. In each month, monthly mean deposition velocities for the highest year are twice that for the lowest. This interannual variability is not captured by a widely used chemistry-transport model with the classic ozone dry deposition scheme. Two independent stomatal conductance estimates, based on either water vapor fluxes or gross primary productivity from carbon dioxide fluxes, vary little from year to year relative to canopy conductance. We conclude that nonstomatal deposition controls the substantial observed interannual variability in summertime deposition velocities during the 1990s over this deciduous forest. The absence of obvious relationships between meteorology or biophysical controls and deposition velocities during the 1990s implies a need for additional long-term, high-quality measurements, and further investigation of nonstomatal mechanisms. On daily timescales, we find that stomatal uptake is an important driver of variability in ozone deposition velocities at Harvard Forest. We extend our analysis of day-to-day variability spatially, using short-term observations from forests and agricultural sites in the eastern USA and the NOAA GFDL land model with a modified Wesely [1989] scheme.

B305ORAL-0367: Ozone concentrations and its drivers in the remote Amazon – Measured and modelled effects of sources, sinks, turbulence and chemical reactions under increasing deforestation rates and different meteorological conditions

Stefan Wolff1, Anywhere Tsokankunku1, Christopher Pöhlker1, Jorge Saturno1, David Walter1, Jost Lavric2, Laurens Ganzeveld3, Andrea Pozzer1, Florian Ditas1, Tobias Könemann1, Ana Maria Yáñez-Serrano1, 4, Jürgen Kesselmeier1, Rodrigo Souza5, Ivonne Trebs1, 6, Matthias Sörgel1

1Multiphase Chemistry, Biogeochemistry and Atmospheric Chemistry Departments, Max Planck Institute for Chemistry – Mainz, Germany, Mainz, Germany 2Max Planck Institute for Biogeochemistry – Jena, Germany, Jena, Germany 3Environmental Sciences Department, WUR – Wageningen, The Netherlands, Wageningen, The Netherlands 4now at: Institute of Ecosystem Physiology, Department of Forest Science, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany 5Escola Superior de Tecnologia, Universidade do Estado do Amazonas (UEA), Manaus, AM, Brazil, Manaus, Brazil 6now at: Luxembourg Institute of Science and Technology, Environmental Research and Innovation (ERIN) Department, Belvaux, Luxembourg

Within the remote Amazon rainforest, the Amazon Tall Tower Observatory site (ATTO; 02°08’38.8’’S, 58°59’59.5’’W) allows atmospheric and forest studies away from nearby anthropogenic emission sources. Continuous measurements of atmospheric H2O, CO2 and O3 mixing ratio profiles started in April 2012 at eight different heights between 0.05 and 80 m above ground, establishing the longest continuous record of near surface O3 in the Amazon rainforest up to date. In addition, NOx was measured for several months between 2013-2016, and from March 2016 on, direct flux measurements of O3 are available. Black carbon (BC), CO and micro-meteorological measurements are also available since 2012.
 
Within the Central Amazon, precipitation displays clear seasonal patterns (on average ca. 350 mm in March and ca. 80 mm in September based on long-term records for Amazon sites and on 4-year ATTO data). These variations are correlating strongly with ozone mixing ratios, which are, in turn, controlled by ozone production, deposition, atmospheric turbulence and chemical reactions. Since 2012, the deforestation rates and the associated biomass burning in the Amazon area have increased, and this has led to higher air pollution by aerosols, etc., especially during the drier season. We compared the effects of long and short distance biomass burning on O3 and NOx mixing ratios using back trajectories and satellite data. We investigated yearly correlation patterns of O3 mixing ratios with solar radiation, Bowen ratio, several trace gases and aerosol loads (Volatile Organic Compounds, CO and BC) in an attempt to better understand the sources and sinks of ozone. Comparisons with measured data and outputs of the canopy exchange model MLC-CHEM“ were used to analyze in canopy absorption processes, whereas the ECHAM/MESSy Atmospheric Chemistry (EMAC) model was applied to investigate transport and distribution patterns of O3 in the atmospheric boundary layer for a period of 34 months.

B306ORAL-0024: Seasonal changes in isoprene emission and deposition in the Amazon Tall Tower Observatory - ATTO

Eliane Gomes Alves1, Julio Tota2, Andrew Turnipseed3, José Oscar Vega4, Paula Corain Lopes4, Raoni Aquino Santana2, Glauber Cirino1, Julia Tavares1, Aline Lopes1, Bruce Nelson1, Diogo Rosa1, Dalton Vale1, Rodrigo Souza5, Dasa Gu6, Trissevgeni Stavrakou7, David Adams8, Jin Wu9, Scott Saleska10, Cleo Dias-Junior11, Ana Maria Yáñez-Serrano12, Jürgen Kesselmeier13, Thomas Karl14, Antonio Manzi15, Alex Guenther6

1Environment Dynamics Department, National Institute for Amazonian Research , Manaus, Brazil 2Institute of Engineering and Geoscience, Federal University of West Para , Santarem, Brazil 3Atmospheric Chemistry Division, National Center for Atmospheric Research , Boulder, The United States of America 4Chemistry and Environment Center, National Institute for Energetic and Nuclear Research, São Paulo, Brazil 5Meteorology Department, State University of Amazonas , Manaus, Brazil 6Department of Earth System Science, University of California, Irvine, The United States of America 7Belgian Institute for Space Aeronomy, Brussels, Belgium 8Centro de Ciencias de la Atmósfera, Universidad Nacional Autónoma de México, Mexico city, Mexico 9Terrestrial Ecosystem Science and Technology, Brookhaven National Laboratory, Upton, The United States of America 10Ecology and Evolutionary Biology Department, University of Arizona, Tucson, The United States of America 11Federal Institute of Para, Bragança, Brazil 12Forest Science Department, Institute of Ecosystem Physiology, Freiburg, Germany 13Biogeochemistry Department, Max Planck Institute for Chemistry, Mainz, Germany 14Institute of Meteorology and Geophysics, University of Innsbruck, Innsbruck, Austria 15National Institute for Spatial Research, Center of Weather Forecasting and Climate Studies, Cachoeira Paulista, Brazil

Seasonal variations in isoprene fluxes were investigated in a primary rainforest in central Amazonia. Fluxes calculated with canopy gradient concentration profiles and an Inverse Lagrangian Transport model are presented for intensive campaigns from November 2012 to October 2015. Measurements were compared to top-down isoprene emission estimates derived from satellite formaldehyde observations with a resolution of 0.5º, and to bottom-up model estimates (MEGAN 2.1). The MEGAN 2.1 leaf age algorithm was driven by inputs from the results of a leaf demography-ontogeny model that uses leaf flushing observed in the field. For comparison, MEGAN 2.1 was additionally run in default mode, where leaf age fractions are estimated from LAI changes (MODIS). Observed fluxes showed seasonal variation, with the highest emissions during the dry and dry-to-wet transition seasons. Net deposition was observed in the wet and the wet-to-dry transition seasons. Top-down estimates of isoprene emission showed a similar trend compared to the seasonal variation of ground-based measurements, with emissions increasing toward the dry season. Both MEGAN 2.1 estimates did not capture the seasonal behavior observed in the field, and model emissions overestimated the observations. Using the leaf phenology observed in the field as inputs for the leaf age algorithm of MEGAN 2.1, improved estimates of the proportion of leaves in different leaf age categories for the site but did not change the relative isoprene emission capacity used for each age class. We suggest that the lack of knowledge on isoprene emission capacity of different leaf ages is probably the main reason why MEGAN 2.1 did not catch the seasonal behavior observed. More measurements are needed to improve our understanding of seasonal isoprene emissions and the potential of isoprene deposition in Amazonia. This will advance surface emission and deposition models that will subsequently lead to a better predictive capability of atmospheric chemistry and climate.

B307 - ORAL-0349: Atmosphere-vegetation coupling: Implications for in-situ observations and modeling of energy, water and trace-gas exchange

Edward (Ned) Patton1

1National Center for Atmospheric Research, Boulder, CO, The United States of America

Large-eddy simulation of atmospheric boundary layers interacting with a coupled and resolved plant canopy reveals the influence of atmospheric stability variations from neutral to free convection on turbulence. Instantaneous fields show that organized motions on the scale of the atmospheric boundary layer (ABL) depth bring high momentum down to the top of the canopy, locally modulating the vertical shear of the horizontal wind at canopy top.  The character of these ABL-scale structures evolve with increasing instability. Linkages between atmospheric turbulence and biological control alters horizontal leaf temperature distributions and therefore scalar source/sink distributions, which has implications for in-situ observations and modeling of land-surface exchange.

B308ORAL-0412: Fluxes of Sensible Heat of Oil Palm Plantation in Jambi Indonesia as influenced by surface roughness characteristics and atmospheric stability.

Tania June1, Ana Meijide2, 3, Alexander Knohl2

1Agrometerology Laboratory Department of Geophysics and Meteorology Faculty of Mathematics and Natural Sciences, Bogor, Indonesia 2Institute of Bioclimatology, University of Gottingen, Gottingen, Germany 3Department of Ecology, University of Granada, Spain, Granada, Spain

Turbulence characteristics above a vegetated surface and the transfer of momentum, exchange of heat and water vapour between this vegetated surface and the air above it within the surface boundary layer are complex processes that control many hydrological, agricultural and atmospheric system. Turbulence within the surface boundary layer is affected both by atmospheric stability and roughness characteristics of the surface.
 
A study was conducted on oil palm plantation, which is expanding vastly in Jambi Indonesia,   and hypothesized to result in altered surface roughness and turbulence characteristics influencing the local climate. Micrometeorology vertical profile measurements were conducted above the oil palm canopy, which include air temperature, wind speed and air pressure, for the period 2014 – 2015. The plantation has an area of 2025 ha and the oil palm were planted in 1999 and 2002. The exact location of the tower is at S01°41'35.0'', E 103°23'29.0''. Analysis of turbulence characteristics, surface roughness and sensible heat fluxes were conducted by looking at the boundary layer development d, atmospheric characteristics profiles and gradient (wind speed, and temperature), surface roughness (roughness length zo and zero plane displacement, d), turbulence transfer coefficient K, mean eddy diameter l=kz and mean eddy velocities/ friction velocity u*, shearing stress t, and aerodynamic resistance. Fluxes of heat were calculated using profile similarity methods taking into account atmospheric stability, neutral, unstable and inversion/stable by calculating Richardson Number Ri , Monin Obukhov length L, and generalized stability factor. 
 
Research on surface roughness, turbulence characteristics and fluxes on oil palm is very limited, and none ever conducted on oil palm plantation. Although eddy covariance is now commonly used for energy/momentum/mass fluxes measurement, the understanding of profile similarity methods is needed for large-scale models and have advantages in terms of simplicity of instrumentation. 

B309ORAL-0348: Simulating BVOC emissions with the photosynthesis-emission model JJv within a ecosystem site model and a global scale land model: A sensitivity study

Felix Wiß1, Tim Butler2, Rüdiger Grote1

1Karlsruhe Institute of Technology, Institute of Meteorology and Climate research, Atmospheric Environmental Research, Garmisch-Partenkirchen, Germany 2Institute for Advanced Sustainibility Studies, Potsdam, Germany

Different plants emit different amounts and different kinds of volatile organic compounds (BVOCs) that have the potential to change chemical processes in the troposphere. Depending on the tropospheric conditions and the composition of emitted compounds, BVOCs can especially impact the air quality and the local climate. For a better understanding of these potential impacts, it is crucial to represent spatial and temporal distribution of BVOC exchange rates, which means that models not only need species-specific emission parameters but also to reproduce canopy structure (e.g., leaf biomass) and physiological processes (e.g., carbon assimilation) over the growing period. Only then, BVOC emissions may be simulated under changing future conditions of temperature, CO2 concentrations, and combinations of plant stress factors such as heat and droughts.
 
Here we present the semi-mechanistic BVOC emission model JJv which is explicitly linked to photosynthesis, and evaluate its applicability at different spatial scales. Therefore, we performed a sensitivity study by implementing the JJv model into the framework of two different models: the 1-D biogeochemical site specific ecosystem model Landscape DeNitrifiaction and DeComposition (LDNDC) and the global scale Community Land Model (CLM) version 4.5. Both models simulate biophysical and biogeochemical processes within the canopy in a similar way so that the JJv model can be coupled using the same parameters. We simulate emissions with i) species-specific parameters and a high vertical resolution; ii) species-specific parameterization but a reduced number of vertical layers as generally used in global models; and iii) the reduced number and extent of vertical layers as used before but a lumped parameterization and compare results with measurements from differently structured forest ecosystems. The analysis addresses the question which degree of structural simplification is necessary to represent emissions from complex canopies and if current global models are up to the task or need to be elaborated.

B310 - ORAL-0242: Boreal forest BVOCs exchange: emissions versus in-canopy sinks

Putian Zhou1, Laurens Ganzeveld2, Ditte Taipale3, 4, Üllar Rannik1, Pekka Rantala1, Matti Rissanen1, Dean Chen1, Michael Boy1

1Department of Physics, University of Helsinki, Helsinki, Finland 2Wageningen University, Wageningen, The Netherlands 3Department of Forest Sciences, University of Helsinki, Helsinki, Finland 4Estonian University of Life Sciences, Department of Plant Physiology, Tartu, Estonia

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 numerous 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+MBO, sesquiterpenes and several their oxidation products) in July, 2010 at the boreal forest site SMEAR II (Station to Measure Ecosystem-Atmosphere Relations II).
 
The modeled sources and sinks show both diurnal and vertical variations, resulting in upward or downward BVOC fluxes over the canopy or characteristic BVOC exchange processes inside the canopy. 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+MBO), (2) chemical reactions remove a significant portion of the 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). 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.

B311ORAL-0074: Biotic plant stress induce formation and growth of new particles tremendously

Ditte Taipale1, 2, Veli-Matti Kerminen1, Markku Kulmala1, Ülo Niinemets2

1Department of Physics, University of Helsinki, Helsinki, Finland 2Department of Plant Physiology, Estonian University of Life Sciences, Tartu, Estonia

Vegetation is the largest source of volatile organic compounds (VOCs) in the atmosphere. Much attention has been given to representing the constitutive emissions of VOCs in various modelling efforts. Unfortunately, VOC emissions caused by stress, and especially biotic stress, have been mostly excluded. As stress induced emission has been forecast to increase in frequency and severity in a warmer climate, the neglect of stress-dependent emission in climatic models is becoming one of the key obstacle for realistic climatic predictions. We constructed a model to study the impact of biotic plant stresses on new particle formation (NPF) and growth. The model includes the most recent advances in extremely low volatility organic compounds chemistry. Sulfuric acid and organic vapours participate in both the formation and condensational growth of new particles via non-equilibrium gas-particle partitioning. Published records on the emissions of VOCs from oak, poplar and birch due to herbivory and fungal infections are also implemented. We predicted the formation and growth of new particles from these broadleaved species in stress-free conditions and under various levels of infection. We found that severely infected broadleaved tree stands can produce up to one order of magnitude more new particles than what has been found in boreal tree stands. This is striking as the investigated broadleaved tree species emit almost exclusively isoprene constitutively, hence no new particles are formed in stress-free conditions. Additionally, our results show that even mild stress leads to significant NPF. Since plants often experience some degree of stress, our findings suggest that global NPF events are presently significantly underestimated both in commonness and magnitude in current, and especially future climate. Effectively, this means that also the production of cloud condensation nuclei could be highly
underestimated, hence atmospheric aerosols are possibly accounting for a larger negative radiative effect than what is currently thought.

Withdrawn - POSTER-0088: The effects of canopy mixing on fluxes and vertical concentration gradient of VOCs above a forest canopy

Kirsti Ashworth1, Allison Steiner2, Serena Chung3, 4

1Lancaster University, Lancaster, United Kingdom 2University of Michigan, Ann Arbor, MI, The United States of America 3Washington State University, Pullman, WA, The United States of America 4now at US EPA, Washington DC, The United States of America

 

Fluxes of biogenic Volatile Organic Compounds from forest ecosystems account for over three-quarters of the hydrocarbons annually released to the atmosphere. The atmospheric reactions of these compounds affect the composition, chemistry and oxidative capacity of the troposphere on all time and spatial scales. They are well-documented precursors of ozone and aerosol as well as a source of reactive nitrogen to remote regions. In spite of recent advances in our understanding of their reactions across a spectrum of NOx regimes, models are often still unable to reconcile simulated concentrations and fluxes of bVOCs with those measured in and above forest canopies, particularly in regions where NOx concentrations are moderate (~1-2 ppbv). We apply the FORCAsT (FORest Canopy Atmosphere Transfer) canopy exchange model to a rural mixed deciduous forest site in the mid-latitudes where NOx mixing ratios are typically around this level. We explore the canopy processes controlling exchanges of isoprene and its oxidation products methyl vinyl ketone and methacrolein between the forest canopy and the atmosphere. While isoprene fluxes are always positive, bi-directional exchange of methyl vinyl ketone and methacrolein has been observed at many sites. Furthermore, the chemical lifetime of isoprene is of a similar order to the canopy retention time making vertical exchange processes important. We conclude that for such species understanding and better accounting for turbulent mixing is as important as chemistry in determining canopy-top fluxes.

B312 - POSTER-0359: Monoterpene chemical speciation at Amazonian Tall Tower Observatory (ATTO) tropical rainforest: observations and simulations

Ana Maria Yáñez-Serrano2, 1, Laurens Ganzeveld3, Anke Noelscher4, Efstratios Bourtsoukidis4, Stefan Wolff2, Eliane Gomes Alves5, Jonathan Williams4, Meinrat Andreae2, Jürgen Kesselmeier2

1Chair of Ecosystem Physiology, University of Freiburg, Freiburg, Germany 2Biogeochemistry Department, Max Planck Institute for Chemistry, Mainz, Germany 3Wageningen University, Wageningen, The Netherlands 4Air Chemistry Department, Max Plank Institute for Chemistry, Mainz, Germany 5National Institute for Amazonian research, Manaus, Brazil

Speciated monoterpenes measurements in Amazon rainforest air are relatively scarce but important in order to understand the contribution of monoterpenes to the overall reactivity and secondary aerosol formation associated with volatile organic compounds (VOCs) emissions into the tropical forest boundary layer. In this study, we present the chemical speciation of gas phase monoterpenes within the tropical rainforest of the Amazonian Tall Tower Observatory (ATTO) based on analysis of the observed monoterpene mixing ratios at 12 and 24m within the canopy. This analysis also relies on the application of offline version of Multi Layer Canopy Chemical Exchange Model (MLC-CHEM) driven by the observed micro-meteorology and ozone surface layer mixing ratios to evaluate these monoterpene concentration measurements as a function of in-canopy interactions between the emissions, in-canopy chemistry, dry deposition and turbulent exchange. The model captures reasonably well the observed magnitude and the temporal variability in different monoterpene mixing ratios. The results also indicate, besides the important role of in-canopy chemical destruction for a selection of the emitted monoterpenes, a potentially important effect of canopy wet surface deposition.  The latter must be further investigated with extensive measurements for a better understanding of the processes involved in explain the observed mixing ratios within a rainforest canopy. In addition, this improved understanding of potential canopy sinks is also essential to the inversion of the actual monoterpene emission fluxes from concentration measurements above and inside a forest canopy.

B313 - POSTER-0503: Long-term measurements of ozone deposition over a peat bog

Mhairi Coyle1, Eiko Nemitz1, David Fowler1

1NERC Centre for Ecology & Hydrology (CEH) Edinburgh, Bush Estate, Penicuik, Midlothian, UK, EH26 0QB

The Auchencorth Moss site, located on an area of upland deep peat, with heather and grass cover, is ~18 kilometres south of Edinburgh city centre, Scotland, near Penicuik. It has been operational since 1985 as part of a variety of different monitoring networks and research programs, including various UK networks, ICOS, CarboEurope, NitroEurope, GAW, EU ACTRIS, EMEP (the Co-operative Programme for Monitoring and Evaluation of the Long-range Transmission of Air Pollutants in Europe) Level III monitoring site as well as ECLAIRE. Ozone deposition has been measured at the site since 1986 using a flux-gradient system, which was refurbished and extended in 2011 while a ROFI eddy-covariance ozone sensor was added in November 2012. These data will be used to quantify ozone deposition to the site (segregating stomatal and non-stomatal uptake when possible) as well as examining any observed trends and interactions with other variables.