PO Lunch Seminar and Master's Defense 1 Dec 2021

Wednesday, December 01, 12:30 PM to 01:30 PM PST

Physical Oceanography Lunch Seminar/Master's Defense: Kimberly Gottschalk
Variability in the currents, deep waters, and bottom waters of the Southwest Pacific Basin

12:30 P.M., 425 Ocean Sciences Bldg
and via Zoom: https://washington.zoom.us/j/92092614769

Committee chair: Greg Johnson

ABSTRACT: Deep currents of the Southwest Pacific Ocean are crucial to distributing heat, freshwater, dissolved gasses, nutrients, and other water properties to the Northern Pacific. The Southwest Pacific Deep Western Boundary Current (DWBC) connections with global ocean circulation make understanding the DWBC essential to the climate puzzle. Adding the 2016 re-occupation of WOCE Section P15S, a mostly meridional transect through the Southwest Pacific Basin nominally along 170°W, to previous observations in the 1990s and 2000s, we document continued freshening and warming of bottom water from 2009 to 2016 in the Southwest Pacific basin. Isopycnal height for γn > 28.15 kg m-3 has continued to decrease and southward contraction of the isopycnals, γn > 28.2 kg m-3 in the basin has continued, leaving no remaining water masses with γn > 28.2 kg m-3 north of 20°S at 170°W. The location and strength of the DWBC core vary at the north flank of the Chatham Rise with a salinity maximum, a signature of North Atlantic Deep Water, which has impacts for localized circulation. We explore a direct connection to high latitude atmospheric boundary conditions in the latter half of the 20th century and further demonstrate potential effects of climate on the transport of heat and carbon by the DWBC and call for changes to sampling at DWBC core crossings. 

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