Ocean versus atmosphere control on western European wintertime temperature variability
- 444 Downloads
Using a novel Lagrangian approach, we assess the relative roles of the atmosphere and ocean in setting interannual variability in western European wintertime temperatures. We compute sensible and latent heat fluxes along atmospheric particle trajectories backtracked in time from four western European cities, using a Lagrangian atmospheric dispersion model driven with meteorological reanalysis data. The material time rate of change in potential temperature and the surface turbulent fluxes computed along the trajectory show a high degree of correlation, revealing a dominant control of ocean–atmosphere heat and moisture exchange in setting heat flux variability for atmospheric particles en route to western Europe. We conduct six idealised simulations in which one or more aspects of the climate system is held constant at climatological values and these idealised simulations are compared with a control simulation, in which all components of the climate system vary realistically. The results from these idealised simulations suggest that knowledge of atmospheric pathways is essential for reconstructing the interannual variability in heat flux and western European wintertime temperature, and that variability in these trajectories alone is sufficient to explain at least half of the internannual flux variability. Our idealised simulations also expose an important role for sea surface temperature in setting decadal scale variability of air–sea heat fluxes along the Lagrangian pathways. These results are consistent with previous studies showing that air–sea heat flux variability is driven by the atmosphere on interannual time scales over much of the North Atlantic, whereas the SST plays a leading role on longer time scales. Of particular interest is that the atmospheric control holds for the integrated fluxes along 10-day back trajectories from western Europe on an interannual time scale, despite that many of these trajectories pass over the Gulf Stream and its North Atlantic Current extension, regions where ocean dynamics influence air–sea heat exchange even on a very short time scale.
KeywordsAir–sea interaction Lagrangian method Climate variability
We would like to thank Y. Huang, T. M. Merlis, and B. Tremblay for their useful discussions and comments, and we gratefully acknowledge B. Dattore from NCEP for providing reanalysis data and A. Stohl and his team for making FLEXPART code available. Funding for this work was provided by the NSERC Discovery Program, FQRNT’s Programme Établissement de Nouveaux Chercheurs Universitaires, and Québec-Océan. We would also like to thank two anonymous reviewers who helped us to improve this paper.
- Bjerknes J (1964) Atlantic air–sea interaction. In: Landsberg HE, Van Mieghem J (eds) Adv Geophys. Academic Press, New York, pp 1–82Google Scholar
- Fairall CW, Bradley EF, Hare JE, Grachev AA, Edson JB (2003) Bulk parameterization of air–sea fluxes: updates and verification for the COARE algorithm. J Clim, 571–591Google Scholar
- Gámiz-Fortis SR, Esteban-Parra MJ, Pozo-Vázquez D, Castro-Díez Y (2011) Variability of the monthly European temperature and its association with the Atlantic sea–surface temperature from interannual to multidecadal scales. Int J Climatol 31(14):2115–2140. doi: 10.1002/joc.2219 CrossRefGoogle Scholar
- Maury MF (1860) The physical geography of the sea, and its meteorology. Harper & Brothers, New YorkGoogle Scholar
- McCarthy G, Frajka-Williams E, Johns WE, Baringer MO, Meinen CS, Bryden HL, Rayner D, Duchez A, Roberts C, Cunningham SA (2012) Observed interannual variability of the Atlantic meridional overturning circulation at 26.5N. Geophys Res Lett 39(19). doi: 10.1029/2012GL052933
- Peixoto JP, Oort AH (1992) Physics of climate. American Institute of Physics, New YorkGoogle Scholar
- Rhines PB, Häkkinen S, Josey SA (2008) Is oceanic heat transport significant in the climate system? In: Dickson RR, Meincke J, Rhines PB (eds) Arctic–Subarctic ocean fluxes: defining the role of the Northern Seas in climate. Springer, New York chap 4Google Scholar
- Saha S, Moorthi S, Pan HL, Wu X, Wang JW, Nadiga S, Tripp P, Kistler R, Woollen J, Behringer D, Liu H, Stokes D, Grumbine R, Gayno G, Wang J, Hou YT, Chuang HY, Juang HMH, Sela J, Iredell M, Treadon R, Kleist D, Van Delst P, Keyser D, Derber J, Ek M, Meng J, Wei H, Yang R, Load S, Van Den Dool H, Kumar A, Wang W, Long C, Chelliah M, Xue Y, Huang B, Schemm JK, Ebisuzaki W, Lin R, Xie P, Chen M, Zhou S, Higgins W, Zou CZ, Liu Q, Chen Y, Han Y, Cucurull L, Reynolds RW, Rutledge G, Goldberg M (2010) The NCEP climate forecast system reanalysis. Bull Am Meteorol Soc 91:1015–1057. doi: 10.1175/2010Bams3001.1 CrossRefGoogle Scholar