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Quantifying the direct radiative effect of Saharan dust aerosol over north-west Africa and the tropical Atlantic

Richard Bantges Space & Atmospheric Physics

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Project Aims

• Spatial / temporal variability of dust• Radiative impact on TOA SW & LW• Impact at the surface – temporal & spatial

variability• Develop algorithms to retrieve SW & LW

surface fluxes from satellite observations• From retrievals – dust impact on SRB over

African continent

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Dust aerosol detection

Case Study I: 0000 UTC, 3rd March – 2300 UTC, 5th March, 2004

Red: 12.0-10.8 m, Green: 10.8-8.7 m, Blue: 10.8 m Red: 1.6 m, Green: 0.8 m, Blue: 0.6 m

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1155 UTC 04/03/04

1405 UTC 05/03/04

SEVIRI

MODIS

1200 UTC 04/03/04

1400 UTC 05/03/04

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Diurnal variation in AOD: 05/03/04

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Impact on broad-band TOA reflected SW radiance/flux

05/03/04

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Net surface radiation from satellite observations

• LOwland CAtchment Research (LOCAR)

• Estimates of grid/catchment area average evaporation

• Network of ground stations

• Satellite data (AVHRR, MODIS, SEVIRI)

• Scaling: Point → Field → Catchment

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Benefits

• Temporal & spatial patterns of dust aerosol over African continent

• Enhanced SRB components in the presence of dust aerosol → hydrological balance

• Addition information to use in assessing impacts of climate change on water supply, crops, animal and human conditions