Costas, Susana

Goble, Ronald

Jerez, Sonia

Rebêlo, Luís Pina

Trigo, Ricardo Machado

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Geophysical Research AbstractsVol. 14, EGU2012-9142-1, 2012EGU General Assembly 2012© Author(s) 2012Pulses of aeolian activity and westerly winds intensification in thePortuguese coast during cooling climate eventsS. Costas, S. Jerez, R. Trigo, R. Goble, and L. RebeloUnidade de Geologia Marinha-LNEG, Amadora, Portugal (susana.costas@lneg.pt)The Portuguese coast is dominated by sediment starved shorelines with severe problems of erosion and land loss.Active trangressive dunefields at present are very rare, yet the presence of stable dunefields covering large areasof the Portuguese coast points to a radically different scenario in the past. Here we investigate the aeolian recordfrom central Portugal to understand the conditions triggering aeolian mobilization.Ground penetrating radar (GPR) was used to image the stratigraphy of a cliff-top coastal transgressive dunefieldand reconstruct former windfield regimes. Using optically stimulated luminescence (OSL) five major phasesof aeolian activity were dated at 12.6, 5.6, 1.2, 0.4 and 0.3 ka, and related to coastal instability and enhancedwesterlies. These phases were later reconciled to favorable patterns of atmospheric circulation simulated by globaland regional climate models capable of describing the relevant atmospheric phenomena at both synoptic and localscales, respectively.The results prove that major phases of aeolian activity are associated with the onset of cold climate events ofglobal distribution and coincide with reported pulses of aeolian activity in northwest Europe. This implies thedominance of zonal westerlies along the western coast of Europe from Denmark to Portugal during the onset ofcold climate events. Thus we focused on the potential role played by the most important large-scale pattern ofatmospheric circulation in the northern Hemisphere, the North Atlantic Oscillation (NAO). Model simulationssuggest that the pattern of atmospheric circulation during periods of enhanced aeolian activity is compatible withprolonged negative phases of the North Atlantic Oscillation (NAO).

Pulses of aeolian activity and westerly winds intensification in the Portuguese coast during cooling climate events

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Pulses of aeolian activity and westerly winds intensification in the Portuguese coast during cooling climate events

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