HR: 10:50h
AN: OS22B-03    [Abstracts]
TI: Observations and Measurements of Dust Transport from the Patagonia Desert into the South Atlantic Ocean in 2004 and 2005
AU: * Gasso, S
EM: santiago@climate.gsfc.nasa.gov
AF: UMBC/GSFC, University of Maryland Baltimore County 5523 Research Park Drive, Suite 320, Baltimore, MD 21228 United States
AU: Gaiero, D M
OS22B-03 AF: CIGeS, Facultad de Ciencias Exactas Fí-sicas y Naturales Universidad Nacional de Córdoba Avda. Vélez Sarsfield 1611, Córdoba, X5016CGA Argentina
AU: Villoslada, B
OS22B-03 AF: CIGeS, Facultad de Ciencias Exactas Fí-sicas y Naturales Universidad Nacional de Córdoba Avda. Vélez Sarsfield 1611, Córdoba, X5016CGA Argentina
AU: Liske, E
OS22B-03 AF: 2005 Summer Institute on Atmospheric, Hydrospheric, and Terrestrial Sciences, GSFC/NASA, Greenbelt, MD 20771 United States
AB: The largest continental landmass south of the 40-degree parallel and potentially one of the largest sources of dust into the Southern Ocean (SO) is the Patagonia desert. Most of the estimates of dust outflow and deposition from this region into the South Atlantic Ocean are based on model simulations. However, there are very few measurements available that can corroborate these estimates. Satellite assessments of dust activity offer conflicting views. For example, monthly time series of satellite-derived (e.g. AVHRR and MODIS) aerosol optical depth (AOD) indicate that dust activity is minimal. However, a study with the TOMS Aerosol Index (Prospero et al., 2002) showed that the frequency of dust events is in the range of 7-14 days/month during the years 1978 through 1993. In addition, surface visibility observations along the Patagonian coast confirm that ocean-going dust events do occur during the summer and spring months. These discrepancies indicate fundamental uncertainties regarding the frequency and extent of dust activity in Patagonia. Given that the SO is the largest high-chlorophyll, low-nutrient area in the world and that the flux of nutrient-rich dust has the potential to modify biological activity with possible climatic consequences, it is of interest to have a better understanding of how often and intense are dust events in the Patagonia region. We surveyed the reports of dust activity from surface weather stations in the Patagonia region during the period June, 2004 to April, 2005. These observations were compared with simultaneous MODIS true color pictures and the corresponding aerosol retrievals. In addition, measurements of vertical and horizontal dust flux were collected by dust samplers at four sites along the coast. The horizontal flux measurements were compared with the same estimates derived from MODIS. According to the true color pictures and confirmed by the surface visibility observations, we recorded at least 16 ocean-going dust events. The scale of the events varied from small (single dust plumes along the coast) to large (dust front extending ~600 km). Most of the large events occurred during the late summer. Due to the presence of sun glint, cloud obstruction, or coastal sediments, the MODIS automatic aerosol algorithm did not derive AODs in many instances and, as result, many events were not recorded in the MODIS monthly database. Dust sources are numerous and dust plumes outflow at any place along the coastline (> 1000 km) including some very active sources as far south as in the Tierra del Fuego Island (54S). The main sources identified are coastal saltbeds, inland deflation hollows and receding shores of large lakes. Although some of major emitting points have been included as sources in dust models, there are some notable exceptions, for example most of the coastal sources. We note, in addition, that the scale and diversity of the different sources pose significant challenges with respect to parameterization in global models of dust dispersion.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0315 Biosphere/atmosphere interactions (0426, 1610)
DE: 0368 Troposphere: constituent transport and chemistry
DE: 0426 Biosphere/atmosphere interactions (0315)
DE: 4805 Biogeochemical cycles, processes, and modeling (0412, 0414, 0793, 1615, 4912)
SC: Ocean Sciences [OS]
MN: Fall Meeting 2005