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due to strong variability of wind speed and wind direction. Although sometimes
the model fit measurements quite well, a correlation between model data and
measurements in Barcelona over the 2 year period, 2006 -2007, was rather low
(~0.2). Possible reasons for the discrepancy are discussed in detail by Kishcha
et al. (2009). In particular, it was found that specific features of the chosen
monitoring site could contribute to low correlation between model data and
measurements. In summer, the model underestimated SSA-measurements when
actual sea-wave height did not correspond to observed surface sea winds. In
winter, winds which do not blow from sea to land create sea-salt aerosols over the
sea in the vicinity of Barcelona: these aerosols are not transported inland. Under
these circumstances, the model overestimated sea-salt measurements.
In contrast to Barcelona, Tel-Aviv is located on the east coast of the Mediter-
ranean and is not surrounded by mountains. The direction of sea-salt aerosol
transport from sea to land is the same as the direction of prevailing winds, from
west to east. So it is much easier to predict SSA in Tel-Aviv than in Barcelona. As
seen in
Fig. 1d,
some similarity exists between model data and measurements. The
averaged measured SSA concentrations over the sampling period ranged within
approximately the same intervals: 3 ± 3 μg/m
3
for measurements and 2 ± 2 μg/m
3
for model data. We found (Kishcha et al., 2009) that model errors are mainly
positive, indicating that the model tends to underestimate observations. A possible
reason is that the model does not take into consideration SSA which is produced
by breaking waves in the surf zone.
Acknowledgments
We gratefully acknowledge B. Starobinets for helpful discussion. This study
was supported by the BMBF (Germany) - MOST (Israel) grant number 1946 on global change.
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