Faculty Candidate Seminar - Sarah Purkey

02/16/2016 - 3:30pm


DATE:  February 16, Tuesday, 3:30 p.m.  

LOCATION: Nierenberg Hall 101
SPEAKER:  Sarah Purkey, Ph.D.
Lamont-Doherty Earth Observatory of Columbia University

TITLE:  A decline in strength of the bottom limb of the Meridional Overturning Circulation and implications for the global sea level rise budget

Over the past three decades, the bottom limb of the Meridional Overturning Circulation (MOC) has shown significant variability with large implications for the global heat and sea level rise (SLR) budgets. I will present results from two recent studies quantifying a slowdown in the ventilation of the deep Southern Ocean and the contribution of the deep steric expansion to the total sea level budget. First, using full-depth in-situ ocean data, satellite altimetry, and ocean mass from the Gravity Recovery and Climate Experiment (GRACE), we preform regional and global full-depth SLR budgets both regionally and globally. These full-depth sea level budgets allow for assessment of the global deep and abyssal ocean’s contribution to the SLR budget, which shows that deep warming has contributed roughly 5% to the global SLR budget through thermal expansion. Second, I use conservative tracers collected along a repeat section in the South Pacific, directly downstream from one of the deep-water formation sites, to show that the abyssal waters are 5-10 years older in 2011 than in 1992. This analysis provides strong evidence that the rate of ventilation and circulation within the abyssal Pacific sector of the Southern Ocean has significantly decreased over the past 20 years, thus driving the observed global scale warming of the abyssal ocean.


Faculty Host:   Dan Rudnick (drudnick@ucsd.edu)
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Nierenberg Hall 101