[1] A parameterization of the temporal variation of ammonia (NH 3 ) emission into the atmosphere is proposed. The parameterization relies on several simple submodels reflecting emission from stores and barns, agricultural practice in application of manure, and emission from grown crops. Some of the submodels depend on a simple crop growth model, which again depends on temperature variations throughout the year. The parameterization reflects the differences in agricultural practices, differences in the climate due to latitude/longitude, and differences in meteorological conditions between years. Measured as well as modeled meteorology can be applied by the parameterization, which is developed for use down to single farm level as well as in large-scale physical/statistical Eulerian and Lagrangian air pollution models. The parameterization is based on simple principles and is applied for northwestern Europe. The simple principles ensure that the parameterization may be adapted to other climatic conditions. The proposed parameterization is considered as a large improvement compared to previous simpler models with fixed seasonal variation.Citation: Gyldenkaerne, S., C. Ambelas Skjøth, O. Hertel, and T. Ellermann (2005), A dynamical ammonia emission parameterization for use in air pollution models,

Declines in insect pollinators across Europe have raised concerns about the supply of pollination services to agriculture. Simultaneously, EU agricultural and biofuel policies have encouraged substantial growth in the cultivated area of insect pollinated crops across the continent. Using data from 41 European countries, this study demonstrates that the recommended number of honeybees required to provide crop pollination across Europe has risen 4.9 times as fast as honeybee stocks between 2005 and 2010. Consequently, honeybee stocks were insufficient to supply >90% of demands in 22 countries studied. These findings raise concerns about the capacity of many countries to cope with major losses of wild pollinators and highlight numerous critical gaps in current understanding of pollination service supplies and demands, pointing to a pressing need for further research into this issue.

Deriving a parameterisation of ammonia emissions for use in chemistry-transport models (CTMs) is a complex problem as the emission varies locally as a result of local climate and local agricultural management. In current CTMs such factors are generally not taken into account. This paper demonstrates how local climate and local management can be accounted for in CTMs by applying a modular approach for deriving data as input to a dynamic ammonia emission model for Europe. Default data are obtained from information in the RAINS system, and it is demonstrated how this dynamic emission model based on these input data improves the NH₃ calculations in a CTM model when the results are compared with calculations obtained by traditional methods in emission handling. It is also shown how input data can be modified over a specific target region resulting in even further improvement in performance over this domain. The model code and the obtained default values for the modelling experiments are available as supplementary information to this article for use by the modelling community on similar terms as the EMEP CTM model: the GPL licencse v3

[1] Currently, very simple parameterizations for the seasonal variation of the ammonia (NH 3 ) emissions are used in most air pollution models. This limits the capability to reproduce observed seasonal variations in the NH 3 concentrations in rural regions with agricultural activity. A dynamical parameterization of the temporal variation of NH 3 emission for application into air pollution models has therefore been proposed. The obtained improvements are demonstrated by implementing a dynamical NH 3 emission parameterization into the large-scale air pollution model ACDEP. Meteorology, information about agricultural practice, and a simple crop growth model are the basis for the parameterization.

Abstract. Reactive nitrogen (N r ) compounds have different fates in the atmosphere due to differences in the governing processes of physical transport, deposition and chemical transformation. N r compounds addressed here include reduced nitrogen (NH x : ammonia (NH 3 ) and its reaction product ammonium (NH