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Abstract. Intermittent coherent structures can be responsible for a large fraction of the exchange between a forest canopy and the atmosphere. Quantifying their contribution to momentum and heat fluxes is necessary to interpret measurements of trace gases and aerosols within and above forest canopies. The primary objective of the Community Atmosphere-Biosphere Interactions Experiment (CABINEX) field campaign (10 July 2009 to 9 August 2009) was to study the chemistry of volatile organic compounds (VOC) within and above a forest canopy. In this manuscript we provide an analysis of coherent structures and canopy-atmosphere exchange during CABINEX to support in-canopy gradient measurements of VOC. We quantify the number and duration of coherent structure events and their percent contribution to momentum and heat fluxes with two methods: (1) quadrant-hole analysis, and (2) wavelet analysis. Despite differences in the duration and number of events, both methods predict that coherent structures contribute 40-50 % to momentum fluxes and 44-65 % to heat fluxes during the CABINEX campaign. Contributions associated with coherent structures are slightly greater under stable atmospheric conditions. By comparing heat fluxes within and above the canopy, we determine the degree of coupling between upper canopy and atmosphere, and find that they are coupled the majority of the time. Uncoupled canopyatmosphere events occur in the early morning (4-8 a.m. local time) approximately 30 % of the time. This study conCorrespondence to: A. L. Steiner (alsteiner@umich.edu) firms that coherent structures contribute significantly to the exchange of heat and momentum between the canopy and atmosphere at the CABINEX site, and indicates the need to include these transport processes when studying the mixing and chemical reactions of trace gases and aerosols between a forest canopy and the atmosphere.

The global warming potential of nitrous oxide (N 2 O) and its long atmospheric lifetime mean its presence in the atmosphere is of major concern, and that methods are required to measure and reduce emissions. Large spatial and temporal variations means, however, that simple extrapolation of measured data is inappropriate, and that other methods of quantification are required. Although process-based models have been developed to simulate these emissions, they often require a large amount of input data that is not available at a regional scale, making regional and global emission estimates difficult to achieve. The spatial extent of organic soils means that quantification of emissions from these soil types is also required, but will not be achievable using a process-based model that has not been developed to simulate soil water contents above field capacity or organic soils. The ECOSSE model was developed to overcome these limitations, and with a requirement for only input data that is readily available at a regional scale, it can be used to quantify regional emissions and directly inform land-use change decisions. ECOSSE includes the major processes of nitrogen (N) turnover, with material being exchanged between pools of SOM at rates modified by temperature, soil moisture, soil pH and crop cover. Evaluation of its performance at sitescale is presented to demonstrate its ability to adequately simulate soil N contents and N 2 O emissions from cropland soils in Europe. Mitigation scenarios and sensitivity analyses are also presented to demonstrate how ECOSSE can be used to estimate the impact of future climate and land-use change on N 2 O emissions. C max A constant (set at 50 kg N ha -1 ) that adjusts the maximum rate of nitrification possible [this occurs at high levels of NH 4 ? and will be dependent on soil composition (Parton et al. 1996)] D p Potential denitrification rate (kg N ha -1 layer -1 day -1 ) k nitrif A rate constant for nitrification [set at 0.6 (Bradbury et al. (1993)] m b Biological activity rate modifier m NO 3 Modifies the amount of denitrification depending on soil NO 3 -content m pH A rate modifier due to soil pH m t A rate modifier due to soil temperature m w Soil water rate modifier for decomposition m w0 Soil water rate modifier for decomposition at permanent wilting point and saturation = 0.2 m 0 w Soil water rate modifier for denitrification N d The amount of N emitted from the soil during denitrification (kg N ha -1 layer -1 ) N d;N 2The amount of N 2 gas lost by denitrification (kg N ha -1 day -1 ) N d;N 2 O The amount of N 2 O gas lost by denitrification (kg N ha -1 day -1 ) N d50The soil nitrate content at which denitrification is 50% of its full potential (kg N ha -1 layer -1 ) N FERT N in NH 4 ? and urea in the added fertiliser (kg N ha -1 ) N n Nitrification rate (kg N ha -1 layer -1 ) N n;N 2 O The amount of N 2 O gas released during nitrification (kg N ha -1 day -1 ) N NH 4