Extreme air–sea interaction over the North Atlantic subpolar gyre during the winter of 2013–2014 and its sub-surface legacy
- 783 Downloads
Exceptionally low North American temperatures and record-breaking precipitation over the British Isles during winter 2013–2014 were interconnected by anomalous ocean evaporation over the North Atlantic subpolar gyre region (SPG). This evaporation (or oceanic latent heat release) was accompanied by strong sensible heat loss to the atmosphere. The enhanced heat loss over the SPG was caused by a combination of surface westerly winds from the North American continent and northerly winds from the Nordic Seas region that were colder, drier and stronger than normal. A distinctive feature of the air–sea exchange was that the enhanced heat loss spanned the entire width of the SPG, with evaporation anomalies intensifying in the east while sensible heat flux anomalies were slightly stronger upstream in the west. The immediate impact of the strong air–sea fluxes on the ocean–atmosphere system included a reduction in ocean heat content of the SPG and a shift in basin-scale pathways of ocean heat and atmospheric freshwater transport. Atmospheric reanalysis data and the EN4 ocean data set indicate that a longer-term legacy of the winter has been the enhanced formation of a particularly dense mode of Subpolar Mode Water (SPMW)—one of the precursors of North Atlantic Deep Water and thus an important component of the Atlantic Meridional Overturning Circulation. Using particle trajectory analysis, the likely dispersal of newly-formed SPMW is evaluated, providing evidence for the re-emergence of anomalously cold SPMW in early winter 2014/2015.
KeywordsNorth Atlantic Ocean Air–sea fluxes Ocean heat content Subpolar Mode Water Winter 2013–2014
J. P. G, S. A. J. and B. S were supported by Natural Environment Research Council National Capability funding. R.M. acknowledges the support of a Faculty of Science Research Fellowship awarded by the University of New South Wales, and the support of a 2013 Research Bursary awarded by the Scottish Association for Marine Science. E.V.S. was supported by the Australian Research Council via Grant DE130101336. Z.J. is supported by a studentship from the Graduate School of the National Oceanography Centre Southampton.
- Barnier B, Madec G, Penduff T, Molines J-M, Treguier A-M, Le Sommer J, Beckmann A, Biastoch A, Böning C, Dengg J, Derval C, Durand E, Gulev S, Remy E, Talandier C, Theetten S, Maltrud M, McClean J, De Cuevas B (2006) Impact of partial steps and momentum advection schemes in a global ocean circulation model at eddy permitting resolution. Ocean Dyn 56:543–567. doi: 10.1007/s10236-006-0082-1 CrossRefGoogle Scholar
- DRAKKAR Group (2007) Eddy-permitting ocean circulation hindcasts of past decades. CLIVAR Exch 42, 12(3):8–10Google Scholar
- Duchez A, Frajka-Williams E, Castro N, Hirschi J, Coward A (2014) Seasonal to interannual variability in density around the Canary Islands and their influence on the Atlantic meridional overturning circulation at 26 N. J Geophys Res Oceans 119:1843–1860. doi: 10.1002/2013JC009416 CrossRefGoogle Scholar
- Grist JP, Josey SA, Boehme L, Meredith MP, Laidre KL, Heide- Jørgensen MP, Kovacs KM, Lydersen C, Davidson FJM, Stenson GB, Hammil MO, Marsh R, Coward AC (2014) Seasonal variability of the warm Atlantic Water layer in the vicinity of the Greenland shelf break. Geophys Res Lett 41:8530–8537. doi: 10.1002/2014GL062051 CrossRefGoogle Scholar
- Huntingford C, Marsh T, Scaife AA, Kendon EJ, Hannaford J, Kay AL, Lockwood M, Prudhomme Reynard NS, Parry S, Lowe JA, Screen JA, Ward HC, Roberts M, Stott PA, Bell VA, Bailey M, Jenkins A, Legg T, Otto FEL, Massey MN, Schaller N, Slingo J, Allen MR (2014) Potential influences on the United Kingdom’s floods of winter 2013/14. Nat Clim Change 4:769–777. doi: 10.1038/nclimate2314 CrossRefGoogle Scholar
- Josey SA, Gulev S, Yu L (2013) Exchanges through the ocean surface. In: Siedler G, Griffies S, Gould J, Church J (eds) Ocean circulation and climate, 2nd ed, vol 103. A 21st century perspective, International Geophysics Series. Academic Press, San Diego, pp 115–140Google Scholar
- Kalnay E, Kanamitsu M, Kistler R, Collins W, Deaven D, Gandin L, Iredell M, Saha S, White G, Woollen J, Zhu Y, Leetmaa A, Reynolds R, Chelliah M, Ebisuzaki W, Higgins W, Janowiak J, Mo KC, Ropelewski C, Wang J, Jenne R, Joseph D (1996) The NCEP/NCAR 40-year reanalysis project. Bull Amer Meteor Soc 77:437–471CrossRefGoogle Scholar
- Madec, G (2008) NEMO Ocean Engine, Note du pôle modélisation 27, Institut Pierre-Simon Laplace (IPSL)Google Scholar
- Masumoto Y, Sasaki H, Kagimoto T, Komori N, Ishida A, Sasai Y, Miyama T, Motoi T, Mitsudera H, Takahashi K, Sakuma H, Yamagata T (2004) A fifty-year eddy-resolving simulation of the world ocean: preliminary outcomes of OFES (OGCM for the Earth simulator). J Earth Simul 1:35–56Google Scholar
- Slingo J, Belcher S, Scaife A, McCarthy M, Saulter A, McBeath K, Jenkins A, Huntingford C, Marsh T, Hannaford J, Parry S (2014) The Recent Storms And Floods In The UK. Exeter, UK Met Office. http://nora.nerc.ac.uk/505192/