Interactions between air quality and climate change - Air Pollution Modeling and Its Application - page 449

global circulation model. These two runs will be referred to hereafter as ERA and
ECHAM runs, respectively.
Both runs were compared and validated for PM 10 concentrations using observation
from the EMEP (http://www.emep.int) and EIONET-Airbase (http:// air-climate.
eionet.europa.eu) databases. Only rural background stations fulfilling PM 10 data
completeness requirements were considered. It should be noted, that the distri-
bution of PM 10 sites in the domain is very uneven: for Poland there was only one
PM 10 site in 2000 (see Fig. 1) .
The validation results are given in Table 1 . They indicate quite satisfactory
overall model performance for both runs. Modelling system driven by ECHAM5
performs at least as well as does standard retrospective modelling (ERA run). In
general the system tends to underestimate long-term observations.

Table 1. Validation results of modelling system for ERA and ECHAM runs for reference year
2000

RegCM3-β/EMIL-
v.1/CAMx

Statistical measures
Number of stations, N = 33

ERA run ECHAM run

NMB - Normalized Mean Bias (%) 33.74 35.21

NMSE - Normalized Mean Square Error 0.35 0.31

IA - Index of Agreement 0.51 0.58

Predictions within factor 2 of the observations
(%)

78.80 75.80

During winter season the modelling system is performing better than in spring/
summer seasons. It is also able (in opposite to the CTM's tested in recent study by
Stern et al., 2008) to capture quite well the high concentrations. This is most
likely a result of detailed emission inventory employed in the EMIL model.

3.2. Simulations for present day and near future climate

A satisfactory validation of ECHAM run of WUT modelling system allow for
using this system with predictions of future climate. Two decadal time-slices:
present day (1991-2000) and near future (2041-2050) were simulated, with all
model parameterizations and anthropogenic emissions remained unchanged. For
the future decade the ECHAM5 model was forced by the SRES-A1B IPCC
scenario.
The results presented in Fig. 2 show that annual mean PM 10 concentrations in
near future are close to these for present day.
For the Central-Eastern Europe the differences do not exceed −4.5 to 1.5
µg/m 3 . The highest decrease in PM 10 levels are expected in Eastern Poland as well
as in Belarus, Northern Ukraine and great part of Lithuania.