Iron Enrichment Experiment (IRONEX) 1993

Mixing a batch of iron and SF6

[Image of iron mixing in progress on R/V Iselin]

We participated in the first open ocean iron enrichment study by establishing a Lagrangian reference frame for the experiment, and identifying the physical processes contributing to the dispersion of the SF6 tagged, iron enriched surface patch. A GPS navigated, drogued drifter buoy defined the center of an 8 by 8 km patch of trace iron and SF6 while the mixed layer patch was being formed over a 24 hour period. The buoy telemetered its position to a shipboard computer every 10 minutes allowing a Lagrangian reference frame to be established for the patch formation and subsequent patch mapping over the following 8 days. Continuous ADCP measurements and daily towyo CTD and thermal microstructure measurements helped define the processes responsible for vertical and horizontal spreading of the patch.

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Martin, J. H., K. H. Coale, K.S. Johnson, S.E. Fitzwater, R M Gordon, S. J. Tanner, C. N. Hunter, V. A. Elrod, J. L. Nowicki, T. L. Coley, R. T. Barber, S. Lindley, A. J. Watson, K Van Scoy, C. S. Law, M. I. Liddicoat, R. Ling, T. Stanton, J. Stockel, C. Collins, A. Anderson, R. Bidgare, M. Ondrusek, M. Latasa, F. J. Millero, K. Lee, W. Yao, J. Z. Zhang, G. Friederich, C. Sakamoto, F. Chavez, K. Buck, Z. Kolber, R. Greene, P. Falkowski, S. W. Chisholm, F. Hoge, R. Swift, J. Yungel, S. Turner, P. Nightingale, A. Hatton, P. Liss, N. W. Tindale, 1994. Testing the Iron Hypothesis in Ecosystems of the Equatorial Pacific Ocean. Nature, 371, 123-120.

Law, C. S., A. J. Watson, M. I. Liddicoat and T. P. Stanton, 1997. "Sulphur Hexafluoride as a Tracer of Biogeochemical and Physical Processes in an Open Iron Fertilization Experiment. Deep Sea Research, in press.

Stanton, T. P., C. S. Law and A. J. Watson, 1997. Physical Evolution of the IRONEX-I Open Ocean Tracer Patch. Deep Sea Research, in Press.

Stanton, T. P. Dispersion of a Tracer Patch in an Open Ocean Mixed Layer. In prep