GFDL - Geophysical Fluid Dynamics Laboratory

Walter (Bud) Moxim

Research Meteorologist


Princeton University, 201 Forrestal Rd.

Princeton, NJ 08542


Phone: 609-452-6522

Fax: 609-987-5063

Research Interest:


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role of meteorology in tropospheric transport, deposition, and
variability of atmospheric aerosols.


productivity in vast regions of the world?s oceans is known to be
limited by the supply of iron, an essential nutrient to marine
organisms impacting the production of phytoplankton and eventual
carbon export to the ocean floor. The atmospheric source of iron
originates from mineral dust aerosols in the world deserts. We are
using the GFDL Global Chemical Transport Model to examine the
emission of mineral dust (~3.5% Fe) during desert wind storms; the
chemical processing of iron to a soluble bio-available form during
transport away from source regions; and the subsequent dry surface
deposition and precipitation based column deposition to the ocean

figure shows that most of the North Atlantic Ocean receives its
maximum supply of bio-available iron during summer when mineral dust
from the Sahara desert is transported westward by the subtropical
trade winds and then northward around the Azores high pressure
system. In contrast, the northeast Atlantic maximum occurs during
spring coincident with the observed spring phytoplankton bloom.
During late winter and early spring the intermittent transport of
Saharan dust northwestward into the Atlantic can interact with
synoptic scale low pressure systems and produce large episodes of
bio-available iron deposition.

following figure depicts the complexity of
this type of an event that occurred during late February and early
March 2000.

February 26 (a) a weak storm system is situated over the
south-central Atlantic depicted by the ?L?, while the Azores High
indicated by the ?H? is located off the northwest coast of Africa
producing a strong east to west transport of dust from the Sahara
over the Canary Islands into the Atlantic as simulated by the GFDL
model (b) and observed by satellite (c). The low pressure system
propagates north and strengthens, generating a strong cold front
(thick blue line with triangles) and associated rain fall in the
central Atlantic by March 1 (d). During this time dust has been
transported anti-cyclonically around the Azores High (e) into the
precipitation area east of the cold front producing substantial
deposition of bio-available iron.

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