Regional Atmospheric Modeling System

In addition to dissipation of the substance from the model system through degradation, other dissipative mechanisms can be considered. Neely and Mackay(26) and Mackay(3) have also introduced advection (loss of the chemical from the troposphere via diffusion) and sedimentation (loss of the chemical from dynamic regions of the system by movement deep into sedimentation layers). Both of these mechanisms are then assumed to act in the unit world. This approach makes it possible to investigate the behavior of atmosphere emissions where advection can be a significant process. Therefore, from a regulatory standpoint if the emission rate exceeds the advection rate and degradation processes in a system, accumulation of material could be expected. Based on such an analysis reduction of emissions would be called for. 

Atmospheric aerosol particles modify the radiative transfer in the atmosphere and they have an impact on the cloud formation. Therefore, they alter the weather and they have an impact on climate. The anthropogenic part of this modification of the state of the atmosphere is currently not well understood and it raises the largest uncertainties with respect to climate change (see the IPCC report 2007). We developed a new on-line model system to investigate the aerosol-radiation-interaction on the regional scale. 

The Atmospheric Chemistry Transport modelling system used is based on the off-line coupled CAMx and HIRLAM models has been developed to simulate particulate and gas-phase air pollution on different scales. It has been used to simulate short and longterm releases of different chemical species and air pollution episodes. At present it is run in a pre-operational mode 4 times per day based on 3D meteorological fields produced by the HIRLAM NWP model. Currently this modelling system is setup to perform chemical weather forecasts for a series of chemical species (such as O3, NO, NO2, CO and SO2) and forecasted 2D fields at surface are available for each model as well as an ensemble of models (based on 12 European regional air quality models). The simulated output is publicly available and it is placed at the ECMWF website (http //gems.ecmwf.int/d/products/raq/forecasts/) of the EC FP6 GEMS project. 

SM2-U has been implemented in SUBMESO, a high-resolution atmospheric model developed on the basis of the Advanced Regional Prediction System (ARPS) Version 3 (Xue et al., 2000 [660], 2001 [661]) by Dupont 2001 [157] and in MM5 by Dupont et al., 2004 [159]. Its transposition, implementation and test with operational NWP models (e.g., DMI-HIRLAM, LM) and UAQIFSs is part of the EU-project FUMAPEX (Baklanov and Mestayer, 2004 [33]). 

As described in Section 19.2.3.8, regional models, such as a Baltic Sea model, can get the boundary values for the calculation of surface fluxes from simulations with atmosphere models, which have been carried out previously. This is possible, because the influence of the Baltic Sea on the Northern Hemisphere weather system is only important for local phenomena, and inaccuracy in the feedback from the Baltic Sea to the atmosphere is of minor importance, Schrumm and Backhaus (1999). Widely used datasets, such as the ERA-40 reanalysis data, are improved by assimilation of observations. If surface variables calculated by the ocean model tend to drift away, this is compensated to a large extent by the calculated surface fluxes. For this reason numerical simulations with standalone ocean-ice models can be successful. 

---