Unabated bottom water warming and freshening in the south Pacific Ocean.
Purkey, Sarah G.
Johnson, Gregory C.
Talley, Lynne D.
Sloyan, Bernadette M.
Wijffels, Susan E.
Smethie, William M.
MetadataShow full item record
Keywordabyssal warming; Pacific deep circulation; deep steric sea level; deep warming variability; Antarctic Bottom Water
Abyssal ocean warming contributed substantially to anthropogenic ocean heat uptake and global sea level rise between 1990 and 2010. In the 2010s, several hydrographic sections crossing the South Pacific Ocean were occupied for a third or fourth time since the 1990s, allowing for an assessment of the decadal variability in the local abyssal ocean properties among the 1990s, 2000s, and 2010s. These observations from three decades reveal steady to accelerated bottom water warming since the 1990s. Strong abyssal (z > 4,000 m) warming of 3.5 (±1.4) m°C/year (m°C = 10−3 °C) is observed in the Ross Sea, directly downstream from bottom water formation sites, with warming rates of 2.5 (±0.4) m°C/year to the east in the Amundsen‐Bellingshausen Basin and 1.3 (±0.2) m°C/year to the north in the Southwest Pacific Basin, all associated with a bottom‐intensified descent of the deepest isotherms. Warming is consistently found across all sections and their occupations within each basin, demonstrating that the abyssal warming is monotonic, basin‐wide, and multidecadal. In addition, bottom water freshening was strongest in the Ross Sea, with smaller amplitude in the Amundsen‐Bellingshausen Basin in the 2000s, but is discernible in portions of the Southwest Pacific Basin by the 2010s. These results indicate that bottom water freshening, stemming from strong freshening of Ross Shelf Waters, is being advected along deep isopycnals and mixed into deep basins, albeit on longer timescales than the dynamically driven, wave‐propagated warming signal. We quantify the contribution of the warming to local sea level and heat budgets.
Author Posting. © American Geophysical Union, 2019. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research-Oceans 124(3), (2019): 1778-1794, doi:10.1029/2018JC014775.
Suggested CitationPurkey, S. G., Johnson, G. C., Talley, L. D., Sloyan, B. M., Wijffels, S. E., Smethie, W., Mecking, S., & Katsumata, K. (2019). Unabated bottom water warming and freshening in the south Pacific Ocean. Journal of Geophysical Research-Oceans, 124(3), 1778-1794.
Showing items related by title, author, creator and subject.
Recent increases in water column denitrification in the seasonally suboxic bottom waters of the Santa Barbara Basin White, Margot E.; Rafter, Patrick; Stephens, Brandon M.; Wankel, Scott D.; Aluwihare, Lihini I. (American Geophysical Union, 2019-06-11)Denitrification in the anoxic sediments of the Santa Barbara Basin has been well documented in the historic and modern record, but the regulation of and frequency with which denitrification occurs in the overlying water ...
Precession-driven changes in Iceland–Scotland Overflow Water penetration and bottom water circulation on Gardar Drift since ~ 200 ka Elmore, Aurora C.; Wright, James D.; Chalk, Thomas B. (2015-09-21)Benthic foraminiferal stable isotopic records from a transect of sediment cores south of the Iceland-Scotland Ridge reveal that the penetration depth of Iceland-Scotland Overflow Water (ISOW) varied on orbital timescales ...
Three-dimensional numerical modeling of bottom-diffracted surface-reflected arrivals in the North Pacific [poster] Stephen, Ralph A.; Udovydchenkov, Ilya A.; Bolmer, S. Thompson; Komatitsch, Dimitri; Tromp, Jeroen; Casarotti, Emanuele; Xie, Zhinan; Worcester, Peter F. (2015-12-15)Bottom-diffracted surface-reflected (BDSR) arrivals were first identified in the 2004 Long-range Ocean Acoustic Propagation Experiment (Stephen et al, 2013, JASA, v.134, p.3307-3317). The BDSR mechanism provides a means ...