NERI Air Models ACDEP

The ACDEP model

For a number of years, the ACDEP model has been used for calculating deposition of nitrogen and sulphur to Danish inland areas and waters. From 2004 and onwards, the DEHM model has taken over this task.
See the pages on Deposition calculations for details on the current procedure.

General description and references

The ACDEP model is a trajectory model that calculates concentrations and depositions to different chemical species. Air packets are transported to the receptor points in the model domain, where the depositions and concentrations of the chemical species are needed. The way the air packets are transported - the trajectories - are calculated backwards for 4 days on basis of wind speed and wind direction. At the starting point of the trajectory the air packets are given initial concentrations and thereafter the air packets are transported along the trajectory to the receptor points. In the transport along the trajectory the air packets receive emissions from the sources that are passed and the concentrations of the different chemical species in the air packets are changed through chemical reactions and through diffusion and deposition. The concept of the model is shown in the figure below. The model is separated into 10 layers from the ground and up to 2 kilometers above ground.

A general description of the ACDEP is given in [1]. Many results obtained by the model are also given (and discussed in detail) in [1]. The numerical treatment of the

ACDEP model is discussed in many papers (see, for example, [2] and the references given there). The three-dimensional version of the model is described in [3]. A long term simulation used in the study of relationship between emission sources and high ozone concentrations is presented in [4].

References

1. Hertel, O., Berkowicz, R., Christensen, J., and Hov, Ø., 1993. : "Tests of two Numerical Schemes for use in Atmospheric Transport-Chemistry models." ; Atmospheric Environment, 27A, 16, 2591-2611.
   
   
2. Hertel, O., Christensen, J., and Hov, Ø., 1994: "Modelling the end products of the chemical decomposition of DMS in the marine boundary layer."Atmospheric Environment, 28A, 13, 2431-2450.
   
   
3. Hertel, O., Christensen, J., Runge, E.H., Asman, W.A.H., Berkowicz, R., Hovmand, M.F., and Hov, Ø. 1995. : "Development and Testing of a new Variable Scale Air Pollution Model - ACDEP." Atmospheric Environment, 29, 11, 1267-1290.
   
   
4. Asman, W.A.H., Hertel, O., Berkowicz, R., Christensen, J., Runge, E.H., Sørensen, L. L., Granby, K., Nielsen, H., Jensen, B., Gryning, S. E., Sempreviva, A. M., Larsen, S., Hummelshøj, P., Jensen, N. O., Allerup, P., Jørgensen, J., Madsen, H., Overgaard, S., and Vejen, F., 1995. : "Atmospheric Nitrogen input to the Kattegat Strait. " Ophelia, 42, 5-28.
   
   
5. Hertel, O., and Skov, H., 1996.: "Evaluation of the aerosol contribution to atmospheric nitrogen load to Danish coastal waters 1989-94" J. Aeros. Sci., 27(suppl. 1), 59 -60.