Interannual variation of Gulf Stream heat transport in a high-resolution model forced by reanalysis data

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Article  

  Climate Dynamics
Publisher: Springer-Verlag Heidelberg
ISSN: 0930-7575 (Paper) 1432-0894 (Online)
DOI: 10.1007/s00382-004-0449-2
Issue: Volume 23, Numbers 3-4

Date:  September 2004
Pages: 341 - 351  
Interannual variation of Gulf Stream heat transport in a high-resolution model forced by reanalysis data
N. M. J. Hall1 , B. Barnier1, T. Penduff1 and J. M. Molines1

(1)  LEGI, BP53, 38041 Grenoble Cédex 9, France

Received: 14 November 2003  Accepted: 6 April 2004  Published online: 14 August 2004

Abstract    The variability present in a 1/6th degree Atlantic ocean simulation forced by analysed wind stress and heat flux over a 20-year period is investigated by means of heat transport diagnostics. A section is defined which follows the Gulf Stream and its seaward extension, and transport of heat across this section is analysed to reveal the physical mechanisms responsible for intergyre heat exchanges on a variety of time scales. Heat transport across another section that crosses the Gulf Stream is also diagnosed to reveal the temporal behaviour of the gyre circulation. The Ekman response to wind stress variations accounts for the annual cycle and much of the interannual variability in both measures. For the intergyre heat transports, cancellation by transient-mean flow terms leads to a very weak annual cycle. Transient eddies account for approximately half the total intergyre transport of 0.7 Petawatts. They also account for a significant fraction of the interannual variability, but separate experiments with repeated-annual-cycle forcing indicate that the transient eddy component of the heat transport variability is internally generated. Links between the intergyre transport, the wind-driven gyre circulation, the surface heat budget and the atmospheric North Atlantic Oscillation are discussed.