Preprints
https://doi.org/10.5194/bgd-11-11671-2014
https://doi.org/10.5194/bgd-11-11671-2014
 
31 Jul 2014
31 Jul 2014
Status: this preprint was under review for the journal BG but the revision was not accepted.

Emissions from potential Patagonian dust sources and associated biological response in the Atlantic sector of the Southern Ocean

A. Castagna1, H. Evangelista1, L. G. Tilstra2, and R. Kerr3 A. Castagna et al.
  • 1Laboratório de Radioecologia e Mudanças Globais, Universidade do Estado do Rio de Janeiro – UERJ, Pav. Haroldo L. Cunha/Subsolo, Rua São Francisco Xavier 524, Maracanã 20550-013, Rio de Janeiro, RJ, Brazil
  • 2Climate Research and Seismology Department, Royal Netherlands Meteorological Institute – KNMI, De Bilt, Utrecht, P.O. Box 201, Netherlands
  • 3Laboratório de Estudos dos Oceanos e Clima, Instituto de Oceanografia, Universidade Federal do Rio Grande – FURG, Rio Grande, Rio Grande do Sul, 96203-900, Brazil

Abstract. The effect of Patagonian dust over primary producers in the Southern Ocean has long been disputed. Here we present new remote sensing evidence in favour of dust mediated biological response and postulate a hypothesis to explain the spatial relation observed. A new remote sensing definition of dust source areas based on the Normalized Difference Vegetation Index (NDVI) and Absorbing Aerosol Index (AAI) correlation is presented and interannual variation in AAI is evaluated within the source regions as a proxy for dust activity. Correlation of this data with annual chlorophyll concentration, phytoplankton biomass, and diatom dominance reveals a spatially coherent latitudinal band of positive correlation concentrated between the Polar Front and the Subtropical Front. This pattern is restricted to western areas in the biomass correlation and extends toward Africa for the chlorophyll and diatom correlation. This region is equivalent to the area of the Subantarctic Mode Water formation, characterized by a ratio Si : N ≪ 1 in late summer, an unfavourable condition for diatom development, especially under iron limitation. Therefore, due to Si–Fe co-limitation, the positive correlation could be the consequence of an enhanced sensibility of this area to external iron addition for diatom growth. For the Argentinean shelf-break, is not clear whether direct dust input and/or wind stress driving water masses upwelling could be responsible for the positive correlation.

A. Castagna et al.

 
Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
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Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement

A. Castagna et al.

A. Castagna et al.

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