GEOTRACES: The Importance of Temporal Variability Peter Sedwick Bermuda Institute of Ocean Sciences meridional variation on dissolved Fe in upper 100 m of water column ~0.5 nM GEOTRACES basin-scale ocean sections may extend over time periods of 1-3 months or more observations not synoptic with respect to eolian input and biological uptake/export (Fe, Al, Co, ) possibility of seasonal juxtaposition of data from meriodional sections crossing the equator Period: 19 May-11 August, 2003 Data: C. Measures and W. Landing, from GEOTRACES Science Plan (

Sargasso Sea: apparent seasonal change of ~1.5 nM dissolved Fe in response to eolian input Spring April, 2004 Early Summer June, 2004 Summer July–6 August, 2003

Seasonal evolution of dissolved Fe in a mode-water eddy (April-July 2007): for Fe and other eolian-supplied TEI’s, temporal variability is dominant mode of surface variation biogeochemical models require climatology of TEI’s, not ‘snapshots’ of spatial distribution need to view section data in context of potentially large seasonal/interannual changes how can GEOTRACES assess this temporal variability? 1. anchor sections to time-series observations (BATS, TENATSO, ETSOC, new sites… ) 2. perform repeat/intersecting sections during different seasonal periods

AGU-ASLO-TOS 2008 Ocean Sciences Meeting · 2-7 March · Orlando, Florida, USA Abstract deadline: Oct Trace Metal Biogeochemistry - Interactions Between Atmosphere and Ocean Organizers: Philip W. Boyd, Mark L. Wells, Peter N. Sedwick, Benjamin S. Twining It now is evident that trace metals have entered the biogeochemical mainstream through their pivotal role in the cycling of carbon, silicon, nitrogen, sulfur and phosphorus. The field of trace metal biogeochemistry is rapidly evolving, in part through international programs like GEOTRACES, SOLAS and CLIVAR, but a series of major challenges limit our abilities to incorporate trace metals into models of major element cycling. Trace metal supply to the upper ocean from both underlying waters and atmospheric aerosol transport is poorly constrained, as is trace metal incorporation into biological processes and their export to the deep ocean. An earth system approach is required to fully comprehend the elemental cycles of trace metals, and the increasing use of stable isotopic tracers likely will be an important stepping stone to meet this challenge. These and other trace metal studies are needed to underpin modeling efforts aimed at understanding how ocean biogeochemistry impacts global climate in both the past and into the future. We encourage submissions from the cellular to the ocean basin scale that address these critical issues