Cane, Mark A.

Kamenkovich, Vladimir M.

English

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The University of Southern MississippiThe Aquila Digital CommunityFaculty Publications8-1-1999Comments on "On the Utility and Disutility ofJEBAR" - ReplyMark A. CaneLamont-Doherty Eart Observatory of Columbia UniversityVladimir M. KamenkovichUniversity of Southern Mississippi, vladimir.kamenkovich@usm.eduFollow this and additional works at: http://aquila.usm.edu/fac_pubsPart of the Marine Biology CommonsThis Article is brought to you for free and open access by The Aquila Digital Community. It has been accepted for inclusion in Faculty Publications byan authorized administrator of The Aquila Digital Community. For more information, please contact Joshua.Cromwell@usm.edu.Recommended CitationCane, M. A., Kamenkovich, V. M. (1999). Comments on "On the Utility and Disutility of JEBAR" - Reply. Journal of PhysicalOceanography, 29(8), 2119-2119.Available at: http://aquila.usm.edu/fac_pubs/4772AUGUST 1999 2119N O T E S A N D C O R R E S P O N D E N C Eq 1999 American Meteorological SocietyReplyMARK A. CANELamont-Doherty Earth Observatory of Columbia University, Palisades, New YorkVLADIMIR KAMENKOVICHInstitute of Marine Sciences, Department of Marine Sciences, University of Southern Mississippi, Stennis Space Center, Mississippi15 January 1999 and 24 February 1999We do not agree with Mellor’s (1999) interpretationof our results. We tried to make two points about JE-BAR: (i) it can be a misleading conceptual tool and (ii)calculations with the formulation (1) in Mellor’s com-ment on our note are likely to be error prone.On the first point, a two-layer wind-driven ocean wasoffered as the simplest illustrative example that we couldthink of. While not a comprehensive model for the oceancirculation, it is hardly ‘‘strange.’’ Our point was pre-cisely that while the bottom torque term (BT) is nilbecause bottom topography has no influence on the so-lution, JEBAR is not small. Indeed, in the simple ex-ample we gave of a seamount 0.5 km high and O(500km) wide JEBAR was many times larger than the windstress term. Thus JEBAR gives a wrong impression ofthe importance of bottom relief. This example is relevantto the study of Greatbatch et al. (1991) and Krupitskyand Cane (1997), among others.On the second point, we illustrated how inevitableerrors in data make calculation with (1) hazardous. Werecognize that the Sverdrup balance is an incompletedescription of the ocean circulation, especially, as inMellor’s example, in the vicinity of western boundarycurrents. We don’t say that calculation with (1) is primafacie wrong because it disagrees with Sverdrup balance.In our note we wrote: ‘‘The Eq. (1) with JEBAR iscorrect and can be used for the calculation. However,Corresponding author address: Dr. Mark A. Cane, Lamont-Doh-erty Earth Observatory, Columbia University, 61 Route 9W, P.O. Box1000, Palisades, NY 10964.E-mail: mcane@ldeo.columbia.eduthe results here suggest that doing so amounts to findingthe influence of topography on the vertically integratedtransport from the difference of two large terms.’’ Thisis a poor computational strategy since, if the two termsare not used consistently throughout the model calcu-lation, it is likely to lead to imperfect cancellation andspurious transport values. Sampling problems and otherdata errors make such mismatches inevitable, as ourpaper illustrates. The earliest recognition of this problemthat we are aware of is in Mellor et al (1982).At the end of our paper we suggest a better com-putational strategy might be to use the form (2) andminimize BT ‘‘consistent with reasonable estimates ofdata errors.’’ We didn’t actually carry through this strat-egy for a real world example, but referred the reader toGodfrey (1989) and Bogden et al (1993) for closelyrelated approaches.REFERENCESBogden, P. S., R. E. Davis, and R. Salmon, 1993: The North AtlanticCirculation: Combining simplified dynamics with hydrographicdata. J. Mar. Res., 51, 1–52.Godfrey, J. S., 1989: A Sverdrup model of the depth-integrated flowfor the world ocean allowing for island circulations. Geophys.Astrophys. Fluid Dyn., 45, 89–112.Greatbatch, R. J., A. F. Fanning, A. D. Goulding, and S. Levitus,1991: A diagnosis of interpentadal circulation changes in theNorth Atlantic. J. Geophys. Res., 96, 22 009–22 023.Krupitsky, A., and M. A. Cane, 1997: A two-layer wind-driven oceanmodel in a multiply connected domain with bottom topography.J. Phys. Oceanogr., 27, 2395–2404.Mellor, G., 1999: Comments on ‘‘On the utility and disutility ofJEBAR’’. J. Phys. Oceanogr., 29, 2117–2118., C. R. Mechoso, and E. Keto, 1982: A diagnostic calculationof the general circulation of the Atlantic Ocean. Deep-Sea Res.,29, 1171–1192.

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