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Project CCP1

Aerosol-induced feedbacks in the Earth system

J.-B. W. Stuut, U. Merkel, G. Fischer, J. Burrows
H. Fischer, M. H. Iversen, G. Mollenhauer, C. Vogt, M. Zabel

The aim is to develop a mechanistic understanding of the transport processes of dust and to shed light on the impact of dust deposition on marine environmental processes as a key element in the biogeochemistry of the Earth system, by combining dust records with remote sensing and climate modeling.

Large uncertainties remain in our understanding of the different roles of mineral aerosols in the climate system (IPCC 2007). In addition to affecting the Earth’s radiative balance, it has been suggested that mineral dust plays an important role in marine biogeochemical cycles through fertilization (e.g. Bishop et al. 2002) and ballasting effects (e.g. Armstrong et al. 2009). To enhance the knowledge base, we carry out a multi-disciplinary study of Saharan dust deposited off the northwest African coast and its impact on the North Atlantic . The project combines expertise from OC (on climate modeling and dust-flux reconstructions), SD (on dust mobilization, transport and deposition), and GB (on ballasting) with knowledge gained from remote sensing (partners at FB1). In addition to the interactions with biogeochemical processes,  we quantify dust-related changes of SST (Evan et al. 2009).

Key Hypotheses

  • Mineral aerosol deposition has significant impact on ocean fertilization, ballasting, and related feedbacks.
  • The cooling effect of mineral aerosols on the upper ocean off NW Africa is sufficiently large to induce a positive feedback on dust mobilization via reduced rainfall.

Specific Methods

  • Assessment of deposition processes using marine sediment traps off Cape Blanc, dust-collecting buoys across the Atlantic, and the dust station on Barbados
  • Use of an appropriate set of specific dust-climate and sediment-transport model experiments to assess feedbacks between mineral aerosols and climate (in close cooperation with Projects OC2 and OC3)
  • Use of remote sensing data for studying the relationship between aerosol optical depth (AOD) and characteristics of dust deposition across the Atlantic