DRIVERS, SEASONALITY AND GRAIN-SIZE OF DUST FLUXES AT THE PATAGONIAN COAST (40°-53°S).

D. GAIERO; C. FERRER; KUPCZEWSKI, M.; ROSAKES, AL; CONNON; OSCAR CABRERA

Reikjiavik

Conferencia; International conference on High Latitude Dust 2017; 2017

University of Loughborough

There is a growing scientific interest to account with modern dust flux measurements in a high latitude dust source like Patagonia as it is of significance for regional climatic studies. This region is the only important landmass below the 40°S which are strongly influenced by the SH westerlies and dust emitted from this region may have direct impact on the Southern Ocean. Dust research focusing in this area of the globe is lacking and scant information is available for proper model parameterizations. Since 2004 a dust monitoring program is being performed at 4 localities along the Patagonian coast. Each site is equipped with passive collectors; a 40-cm deep, inverted epoxy-coated fiberglass pyramidal receptacles suited to estimate vertical fluxes (VF) by gravitational deposition and BSNE samplers, to measure wind-blown horizontal fluxes (HF). At Patagonia both, VF and HF, point toward a similar annual variation indicating higher fluxes during spring-summer according to the increase of the mean monthly wind speed and the decrease of the mean monthly relative humidity. Previous estimations based on VF data indicated that ~30 Tg of Patagonian dust are annually supplied to the South Atlantic shelf. New estimations based on HF contradicts this figure, indicating annual fluxes of 900-1400 Tg to the shelf. Having in mind the low efficiency of BSNE devices, these new data should be taken as a minimum estimation. Turbulent conditions at Patagonia promote transport of coarse dust particles. The median grain-size of HF fluctuate between 16 to 67 µm (mean=31 µm), contrasting with a range between 12-33 µm (mean=21 µm) measured at lower latitudes in South America (e.g., The Pampas). Finally, we observed that the natural process of dust emission is being enhanced by the anthropogenic activities developed in the region. The importance of this modern driver will be discussed in this work.