Abstract
Abstract. Fourteen global atmospheric transport models were evaluated by comparing the simulation of 222Rn against measurements at three continental stations in Germany: Heidelberg, Freiburg and Schauinsland. Hourly concentrations simulated by the models using a common 222Rn-flux without temporal variations were investigated for 2002 and 2003. We found that the mean simulated concentrations in Heidelberg are related to the diurnal amplitude of boundary layer height in each model. Summer mean concentrations simulated by individual models were negatively correlated with the seasonal mean of diurnal amplitude of boundary layer height, while in winter the correlation was positive. We also found that the correlations between simulated and measured concentrations at Schauinsland were higher when the simulated concentrations were interpolated to the station altitude in most models. Temporal variations of the mismatch between simulated and measured concentrations suggest that there are significant interannual variations in the 222Rn exhalation rate in this region. We found that the local inversion layer during daytime in summer in Freiburg has a significant effect on 222Rn concentrations. We recommend Freiburg concentrations for validation of models that resolve local stable layers and those at Heidelberg for models without this capability.
Highlights
Variations of boundary layer height (BLH) in terms of altitude above the mean sea level at Heidelberg and Freiburg are compared with those provided from European Centre for Medium Range Weather Forecasts (ECMWF)
The reason for the high correlations of these models is that they explicitly used BLH provided from ECMWF, though details of BLH in these models and the present study are not exactly the same
One difference is that M and N used constant BLH for 3 h while we used hourly BLH from temporal interpolation of the ECMWF forecast for comparison
Summary
Source-receptor relationships for atmospheric compounds, like gases and fine particles, are one of the tools to understand and to manage air quality. A set of source-receptor relationships forms a response matrix, or Jacobian matrix, and plays a central role in making an inverse estimate of sources and sinks of compounds. Global atmospheric transport models have been developed to describe this relationship, and include various pathways. Some examples of these pathways are diffusion in the atmospheric boundary layer (ABL), transport by convection and synoptic disturbances in the free troposphere, interactions with cloud and rain droplets, chemical reactions, dry and wet deposition to the surface. There is a variety of realism in the modeling of each process. Validation of the source-receptor relationship is required for effective application of emission control, both technically and politically.
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