Modelling Activities
The magnitude and sign of the radiative effect of Arctic haze remains still uncertain. On the one hand, the lack of consistent observations of the spatial and time variations of the aerosol concentrations, including their optical properties, prevents up to now a realistic estimation of the climate signal due to the aerosols. On the other hand, the required model simulations need sophisticated aerosol, cloud and radiation parameterizations which are in development.
The main intention of the project here is to calculate the radiative forcing due to the Arctic haze aerosols with a variety of models of different complexity using measured aerosol properties. We will compare the aerosol effect to other forcing mechanisms to see the relative impact of the haze events.
1. Specific objectives & working program
The specific contribution to the proposed project concerns 1d and 3d model studies of the radiative effects due to Arctic tropospheric aerosols. The importance of including aerosol properties in models that simulate arctic climate is investigated. For a realistic estimation of the climatic effect of Arctic haze, it is necessary to incorporate aerosol in a 3d climate model. A regional atmospheric climate model, called HIRHAM, is used over an Arctic integration area covering the whole Arctic north of 65 N. HIRHAM will be integrated over such seasons, where Arctic haze typically occurs, i.e. over spring seasons. It will be investigated which influence exerts the aerosol on the radiative budget and to what extent the possible changes of the heating rates do influence the monthly mean atmospheric structures due to changed vertical exchange processes. Due to the high horizontal resolution of the model it is possible to simulate both the influence on the large-scale and on the meso-scale atmospheric structures. The dependence of the aerosol climate signal on the optical properties of the aerosols and on clouds will also be investigated on the basis of a variety of sensitivity studies.
Specific objectives
- 1d radiative transport modeling studies for the point Ny Alesund
- implementation of the Global Aerosol Data Set (GADS) into HIRHAM
- HIRHAM spring simulations of the Arctic circulation
- study the aerosol influence on the atmospheric circulation
- incorporation of a newly developed (by ASTAR2000 campaign) Arctic aerosol dataset into HIRHAM
- simulations for the ASTAR2000 period
GADS
Koepke, Hess, Schult, Shettle, 1997: Global Aerosol Data Set. Report No. 243, Max-Planck-Institut
für Meteorologie, Hamburg.
further information:
http://www.lrz-muenchen.de/~uh234an/www/mitarb/kohe97.html
http://www.dkrz.de/dkrz/j94/00-jahresbericht94Book_21.html
Model description
View papers and recent poster presentations
Papers
Dethloff, K., A. Rinke, R. Lehmann, J. H. Christensen, M. Botzet, B. Machenhauer, 1996: Regional climate model of the Arctic atmosphere. J. Geophys. Res. 101, 23401-23422.
Rinke, A., K. Dethloff, J. H. Christensen, M. Botzet, B. Machenhauer, 1997: Simulation and validation of Arctic radiation and clouds in a regional climate model. J. Geophys. Res. 102, 29833-29847.
Rinke, A., K. Dethloff, A. Spekat, W. Enke, J. H. Christensen, 1999: High resolution climate simulations over the Arctic. Polar Res. 18 (2), 1-9.
Rinke, A., K. Dethloff, J. H. Christensen, 1999: Arctic winter climate and its interannual variations simulated by a regional climate model. J. Geophys. Res. 104, 19027-19038.
Rinke, A., K. Dethloff, 2000: On the sensitivity of a regional Arctic climate model to initial and boundary conditions. Clim. Res. 14(2), 101-113.
Dethloff, K., C. Abegg, A. Rinke, I. Hebestad, V. Romanov, 2000: Sensitivity of Arctic climate simulations to different boundary layer parameterizations in a regional climate model. accepted by Tellus.
Dorn, W., K. Dethloff, A. Rinke, M. Botzet, 1999: Distinct circulation states of the Arctic atmosphere induced by natural climate variability. accepted by J. Geophys. Res.
Rinke, A., A. H. Lynch, K. Dethloff, 1999: Intercomparison of Arctic regional climate simulations: Case studies of January and June 1990. accepted by J. Geophys. Res.
Recent posters
Fortmann,Rinke,Dethloff,Christensen, 2000: The direct influence of Arctic aerosol during early spring in a regional climate model. EGS 2000, poster presentation.