van der Graaf, Shelley C.;
Dammers, Enrico;
Schaap, Martijn;
Erisman, Jan Willem
Technical note: How are NH<sub>3</sub> dry deposition estimates affected by combining the LOTOS-EUROS model with IASI-NH<sub>3</sub> satellite observations?
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Media type:
E-Article
Title:
Technical note: How are NH<sub>3</sub> dry deposition estimates affected by combining the LOTOS-EUROS model with IASI-NH<sub>3</sub> satellite observations?
Contributor:
van der Graaf, Shelley C.;
Dammers, Enrico;
Schaap, Martijn;
Erisman, Jan Willem
Description:
<jats:p>Abstract. Atmospheric levels of reactive
nitrogen have increased substantially during the last century resulting in
increased nitrogen deposition to ecosystems, causing harmful effects such as
soil acidification, reduction in plant biodiversity and eutrophication in
lakes and the ocean. Recent developments in the use of atmospheric remote
sensing enabled us to resolve concentration fields of NH3 with larger
spatial coverage. These observations may be used to improve the
quantification of NH3 deposition. In this paper, we use a relatively
simple, data-driven method to derive dry deposition fluxes and surface
concentrations of NH3 for Europe and for the Netherlands. The aim of
this paper is to determine the applicability and the limitations of this
method for NH3. Space-born observations of the Infrared Atmospheric
Sounding Interferometer (IASI) and the LOTOS-EUROS atmospheric transport
model are used. The original modelled dry NH3 deposition flux from
LOTOS-EUROS and the flux inferred from IASI are compared to indicate areas
with large discrepancies between the two. In these areas, potential model or
emission improvements are needed. The largest differences in derived dry
deposition fluxes occur in large parts of central Europe, where the
satellite-observed NH3 concentrations are higher than the modelled
ones, and in Switzerland, northern Italy (Po Valley) and southern Turkey,
where the modelled NH3 concentrations are higher than the
satellite-observed ones. A sensitivity analysis of eight model input parameters
important for NH3 dry deposition modelling showed that the
IASI-derived dry NH3 deposition fluxes may vary from ∼ 20 %
up to ∼50 % throughout Europe. Variations in the NH3 dry
deposition velocity led to the largest deviations in the IASI-derived dry
NH3 deposition flux and should be focused on in the future. A
comparison of NH3 surface concentrations with in situ measurements of
several established networks – the European
Monitoring and Evaluation Programme (EMEP), Meetnet Ammoniak in
Natuurgebieden (MAN) and Landelijk Meetnet Luchtkwaliteit (LML) – showed no significant or
consistent improvement in the IASI-derived NH3 surface concentrations
compared to the originally modelled NH3 surface concentrations from
LOTOS-EUROS. It is concluded that the IASI-derived NH3 deposition
fluxes do not show strong improvements compared to modelled NH3
deposition fluxes and there is a future need for better, more robust, methods
to derive NH3 dry deposition fluxes.
</jats:p>