HR: 0800h
AN: OS51A-1292    [Abstracts]
TI: Large-scale Physical Forcing of Chlorophyll Blooms in the Subtropical Pacific
AU: * Wilson, C
EM: cwilson@pfeg.noaa.gov
AF: NOAA/NMFS/SWFSC PFEL, 1352 Lighthouse Ave., Pacific Grove, CA 93950-2097 United States
AU: Villareal, T
AF: Marine Science Institute, The University of Texas at Austin 750 Channel View Dr., Port Aransas, TX 78373 United States
AU: Bograd, S J
AF: NOAA/NMFS/SWFSC PFEL, 1352 Lighthouse Ave., Pacific Grove, CA 93950-2097 United States
AB: Large chlorophyll blooms observable with ocean color satellite data develop in late summer in the oligotrophic subtropical Pacific, northeast of Hawaii [Wilson, 2003]. These blooms are uncharacterized and the mechanisms that stimulate them are unknown. The blooms are quite large, the largest ones reaching the size of California, but there is significant interannual variation in their size and occurrence. They have been observed in 10 of 16 years of satellite ocean color data, with shorter ones lasting $\sim$6 weeks and longer ones up to 5 months. The two most consistent aspects of the blooms are the timing of their development, occurring in late summer, and their location, centered along $30\deg$N between $140\deg-160\deg$W, approximately $10\deg$ south of the transition zone chlorophyll front (TZCF). Possible biological mechanisms for stimulating these blooms include nitrogen fixation and a biologically-mediated vertical transport of nitrate by {\it Rhizosolenia} mats. The latitudinal locations of the chlorophyll blooms are coincident with the highest observed concentrations of {\it Rhizosolenia} mats. Both processes, nitrogen fixation and mat migration, are sensitive to water column stability, which is linked to physical forcing. Furthermore, the relatively consistent position of the blooms within the Pacific basin suggests large-scale physical forcing from either wind stress or the location of the subtropical front. Here we compare the position of the blooms against basin-scale wind patterns and the location of the subtropical front, both climatologically and interannually, to identify unique characteristics of this region that could lead to the development of the observed chlorophyll blooms. Wilson, C., Late summer chlorophyll blooms in the oligotrophic North Pacific subtropical gyre, {\it Geophysical Research Letters}, 30 (18), 1942, doi:10.1029/2003GL017770, 2003.
UR: http://www.pfeg.noaa.gov/$\sim$cwilson/bloom
DE: 9355 Pacific Ocean
DE: 4815 Ecosystems, structure and dynamics
DE: 4855 Plankton
DE: 4800 OCEANOGRAPHY: BIOLOGICAL AND CHEMICAL
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting