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Nosse, C. T., University of Hawaii, Honolulu, USA, nosse@soest.hawaii.edu
Santiago-Mandujano, F. ., University of Hawaii, Honolulu, USA, mandujan@soest.hawaii.edu
Lukas, R. B., University of Hawaii, Honolulu, USA, rlukas@hawaii.edu
Dore, J. E., Montana State University, Bozeman, USA, jdore@montana.edu
Weller, R. A., Woods Hole Oceanographic Institution, Woods Hole, USA, rweller@whoi.edu
Plueddemann, A. J., Woods Hole Oceanographic Institution, Woods Hole, USA, aplueddemann@whoi.edu

RECENT STRONG INTERANNUAL VARIATION DISRUPTED PYCNOCLINE AND ABYSSAL SALINITY TRENDS AT STATION ALOHA

Long-term freshening observed in the main pycnocline (25-26 σθ) at Station ALOHA reversed from 2008-10. The annual average salinity increased by nearly 0.2, reaching the 1992 record maximum for this density range. A larger salinity increase occurred in the upper pycnocline (24.2-25 σθ), where during winter 2008-9 dissolved inorganic carbon abruptly dropped, both absolutely and relative to salinity and alkalinity. Intrusion of anomalous water masses more likely explains the change than biological drawdown of carbon, as nutrient and chlorophyll levels appeared unaffected. Average salinity between 1.15-1.25oC (3500 m) increased by 0.0035 from 1988 to 2006, and then decreased by nearly this amount between 2007 and 2009. From mid-2010 through mid-2011, salinity increased again in the mid-pycnocline and decreased in the upper pycnocline. Climate forcing included a strong La Nina in 2007-2009, the 2009-10 El Nino and the very strong 2010-2011 La Nina. These events generate first-baroclinic mode Rossby waves in the eastern Pacific that propagate westward past Hawaii. Along-isopycnal advection associated with these waves might explain the anomalous conditions.

Poster presentation

Session #:039
Date: 2/23/2012
Time: 17:00 - 18:00
Location: Poster/Exhibit Hall

Presentation is given by student: No

PosterID: A0189