Dust Deposition - Mineral Dust: A Key Player in the Earth System - page 189

Fig. 8.4 Spatial distribution of dust deposition fluxes for the year 2000 as resulting of the median
of the models participating to the AeroCom project ( http://nansen.ipsl.jussieu.fr/AEROCOM )

SEAREX (Sea-Air Exchange Program) Asian Dust Study Network in the North
Pacific (Arimoto et al. 1985 ; Uematsu et al. 1985 ). The annual dust deposition
to the ocean appears to be dominated by sporadic dust events of short duration.
The total deposition of atmospheric mineral material to the central North Pacific
was estimated to be 0.2gm 2 year 1 (Uematsu et al. 1985 ). More recently,

direct measurements of dust deposition (Heimburger et al. 2012 ; Heimburger et al.
2013 ) were performed in the Southern Ocean, one of the regions where dust
deposition is expected to have the strongest biogeochemical impact (see Chap. 14 ) .
Total atmospheric deposition and crustal aerosol concentrations were monitored
at Kerguelen Islands (49 ı 18 0 S, 70 ı 07 0 E) during a short campaign in early 2005
and then continuously for about 2 years (2009-2010). Results show very low
atmospheric dust deposition fluxes compared to those reported in Fig. 8.3 but
higher than those computed for the same oceanic region when applying deposition
velocities to aerosol measurements (Wagener et al. 2008 ).
Figure 8.4 shows the mean deposition fluxes for the year 2000 obtained from the
AeroCom project (Textor et al. 2006 , 2007 ). It provides a synthetic vision of the
spatial distribution of our knowledge of deposition fluxes. Spatial gradients are well
marked with higher values near the source regions. Thus, highest deposition fluxes
are simulated over the Sahara with values of 50-100 g m 2 year 1 , consistent with
available observations (Fig. 8.3 ). Lower values are simulated over smaller deserts
(China, Australia, Namibia, Patagonia). Over oceanic regions, located downwind
source regions, deposition fluxes range from 2 to 50 g m 2 year 1 .