AIRBORNE TRANSPORT OF AEROSOLS INTO THE SOUTH ATLANTIC OCEAN: ASSESSMENT OF SOURCES, HORIZONTAL FLUXES, IRON FERTILIZING POTENTIAL AND IMPACT ON CLIMATE

DIEGO GAIERO, BARBARA VILLOSLADA, SANTIAGO GASSÓ, SUSANA BIDART, EDINEI KOESTNER AND FARID CHEMALE JR

Miramar, Cordba. Argentina

Congreso; Holocene environmental catastophes in South america: from lowlands to the Andes; 2005

CIGeS-ICSU-ICDP

How much aerosol mass is transported from Patagonia to the South Atlantic Ocean (SAO) basin? What are the sources, the frequency and the extent of the delivery of those particles? Is the regional forcing directly or indirectly affected by the presence of aerosols in the region? Is the amount of iron present in those particles able to control biological processes of this oceanic region? Much of the recent studies of dust transport have been dedicated to study Saharan dust and its long-range transport and impact over Central and North America. However, there are no equivalent studies focusing on other regional dust sources such as the Patagonia region (located in the southern end of South America). Due to the increasing man-induced desertification in the area, it is expected that the aeolian flux will rise.  The SAO basin is of particular economical interest because of its active fisheries as well as being one of the most pristine air masses in the world. Because of the large reach and important amounts transported, wind-blown dust has the potential to significantly influence the biological activity in the oceans as well as change the regional climate. For example, it is clear that the amount of iron transported to the ocean plays a critical role in the development of phytoplankton thus affecting the food chain of fisheries. In addition, the presence of airborne matter over the ocean inhibits the incoming solar radiation to reach the surface as wells as it changes cloud’s optical properties. The overall effect results in a poorly known response of the atmospheric-ocean system due to a disruption in the energy input and its feedbacks. To answer the above questions we have started in 2004 a two year-round program of in-situ and remote sensing dust flux measurements and sampling along the Patagonian coast. Preliminary results indicate that ubiquitous ephemeral lakes at the Patagonian surface are strong sources of dust especially during high westerlies winds events. Changes in the frequency and extent of natural inundation occurring on ephemeral lakes systems may lead to significant fluctuations in regional dust loading.