On the seasonal and interannual migrations of the transition zone chlorophyll front

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Read Full Article (file size: 276855 bytes) Cited by GEOPHYSICAL RESEARCH LETTERS, VOL. 31, L17204, doi:10.1029/2004GL020637, 2004 On the seasonal and interannual migrations of the transition zone chlorophyll front Steven J. Bograd Pacific Fisheries Environmental Laboratory, NOAA National Marine Fisheries Service, Pacific Grove, California, USA David G. Foley Joint Institute for Marine and Atmospheric Research, University of Hawaii at Manoa, Honolulu, Hawaii, USA Franklin B. Schwing Pacific Fisheries Environmental Laboratory, NOAA National Marine Fisheries Service, Pacific Grove, California, USA Cara Wilson Pacific Fisheries Environmental Laboratory, NOAA National Marine Fisheries Service, Pacific Grove, California, USA R. Michael Laurs Pacific Fisheries Environmental Laboratory, NOAA National Marine Fisheries Service, Pacific Grove, California, USA Jeffrey J. Polovina Pacific Islands Fisheries Science Center, NOAA National Marine Fisheries Service, Honolulu, Hawaii, USA Evan A. Howell Pacific Islands Fisheries Science Center, NOAA National Marine Fisheries Service, Honolulu, Hawaii, USA Russell E. Brainard Pacific Islands Fisheries Science Center, NOAA National Marine Fisheries Service, Honolulu, Hawaii, USA Abstract High-resolution satellite measurements of ocean color and surface winds, along with historical in situ data, are used to explore interannual variability in the annual migration of the transition zone chlorophyll front (TZCF) in the central North Pacific Ocean. Significant variations in frontal position and annual range were observed, including a significant southerly displacement during El Niño events. This displacement, apparently forced by enhanced surface convergence and vertical mixing in the transition zone, creates vast regions of anomalously high wintertime surface chlorophyll in the North Pacific Subtropical Gyre. A remarkably close correspondence between the positions of the TZCF and the 18°C surface isotherm over a portion of the central North Pacific allows historical temperature data to be used as a proxy for TZCF position. This surface temperature proxy has revealed decadal-scale variability in frontal position, with greater (lesser) annual range and southerly extent following the large-scale 1976–77 (1998–99) climate shifts. Interannual variations in TZCF position could have important implications for the distribution and survival of a number of apex predators that utilize the TZCF as a migratory and foraging habitat. Received 31 May 2004; accepted 9 August 2004; published 2 September 2004. Index Terms: 4223 Oceanography: General: Descriptive and regional oceanography; 4215 Oceanography: General: Climate and interannual variability (3309); 4227 Oceanography: General: Diurnal, seasonal, and annual cycles; 4528 Oceanography: Physical: Fronts and jets; 4899 Oceanography: Biological and Chemical: General or miscellaneous. Read Full Article (file size: 276855 bytes) Cited by Citation: Bograd, S. J., D. G. Foley, F. B. Schwing, C. Wilson, R. M. Laurs, J. J. Polovina, E. A. Howell, and R. E. Brainard (2004), On the seasonal and interannual migrations of the transition zone chlorophyll front, Geophys. Res. Lett., 31, L17204, doi:10.1029/2004GL020637. Copyright 2004 by the American Geophysical Union.

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