|
|
 |
|
|
Ann. Geophys., 20, 2067-2076, 2002
www.ann-geophys.net/20/2067/2002/
© European Geosciences Union 2002
Atmospheric and oceanic dust fluxes in the northeastern tropical Atlantic Ocean: how close a coupling?
A. Bory1,2, F. Dulac1, C. Moulin1, I. Chiapello3,4, P. P. Newton1,5, W. Guelle1, C. E. Lambert1, and G. Bergametti3
1Laboratoire des Sciences du Climat et de l’Environnement, 91198 Gif-sur-Yvette, France
2Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964, USA
3Laboratoire Inter-Universitaire des Systèmes Atmosphériques, Faculté des Sciences et Technologies, 94010 Créteil, France
4Laboratoire d’Optique Atmosphérique, Université des Sciences et Technologies de Lille 59 655 Villeneuve d’Ascq Cedex, France
5School of Biological and Molecular Sciences, Oxford Brookes University, Headington, Oxford OX3 0BP, UK
Correspondence to: A. Bory (bory@ldeo.columbia.edu)
Abstract. Atmospheric inputs to the
ocean of dust originating from Africa are compared with downward dust flux in
the oceanic water column. Atmospheric fluxes were estimated using
remote-sensing-derived dust optical thickness and parameters from a
transport/deposition model (TM2z). Oceanic fluxes were measured directly
over/in two regions of contrasting primary productivity of the northeastern
tropical Atlantic (one mesotrophic and one oligotrophic, located at about 500
and 1500 km off Mauritania) underlying the offshore dust plume. In both
regions, estimates of annual atmospheric dust inputs to the ocean surface are
lower than, but of the same order of magnitude as, oceanic fluxes (49.5 and 8.8
mg.m-2 .d-1 in the mesotrophic and oligotrophic regions).
Part of this mismatch may reflect both a general flaw in the dust grain size
distribution used in transport models, which likely underestimates large
particles, and/or lateral advection to each region of dustier surface waters
from upstream, where dust deposition is higher. Higher-frequency temporal
coupling between atmospheric and oceanic fluxes seems to be
primary-productivity dependent, as hypothesized in previously reported studies.
Key words. Atmospheric composition
and structure (aerosols and particles; geochemical cycles) Oceanography:
biological and chemical (geochemistry)
Full Article in PDF (314 KB) |
|
|
