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Balancing the SOC climatology using inverse analysis with spatially fixed parameter adjustments. COAPEC Project - Balancing the Atlantic Heat and Freshwater Budgets, Report No. 1

Grist, J.P.; Josey, S.A.. 2002 Balancing the SOC climatology using inverse analysis with spatially fixed parameter adjustments. COAPEC Project - Balancing the Atlantic Heat and Freshwater Budgets, Report No. 1. Southampton, UK, Southampton Oceanography Centre, 109pp. (UNSPECIFIED)

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Abstract/Summary

Early results from a project which has the aim of obtaining a balanced version of the SOC climatology using linear inverse analysis techniques are discussed. In particular, we investigate whether a set of balanced fields can be obtained using spatially fixed analysis parameter adjustments which satisfies the requirements of a.) global heat budget closure; b.) consistency with hydrographic estimates of regionally averaged surface heat fluxes, and c.) agreement with independent research buoy measurements. Results of analyses obtained using two formulations of the inverse method with up to ten ocean heat transport constraints distributed throughout the Atlantic and North Pacific oceans are presented. The first formulation is an established technique which utilises the heat transport estimates directly as constraints. The second is a novel application in which pairs of heat transport estimates are used to derive area averaged heat fluxes which are then employed as constraints. The solutions obtained in each case are found to be sensitive to the choice of location of the heat transport estimates when only a small number (less than 5) of constraints are applied. Consequently, we have focused on solutions obtained with the full set of ten hydrographic constraints both with and without the additional requirement that the globally averaged het flux should equal zero. Without this requirement solutions are obtained which have a net heat loss to the atmosphere of between 5 and 7 Wm-2. In order to close the global heat budget exactly it is necessary to specify it as an additional constraint. However, in this case the solution obtained with the heat transport method is not acceptable according to the criterion of Isemer et al. (1989) which requires the magnitude of the parameter adjustments to be smaller than the assumed error range for each. This criterion is satisfied if the requirement of exact closure is relaxed such that the global net heat flux is constrained to be 0±2 Wm-2. In the latter case, the inverse analysis adjustments to the different components of the heat flux are increases of 19% to the latent heat flux, 7% to the sensible heat flux, 9% to the longwave flux and a reduction of 6% to the shortwave flux. Comparison of the adjusted fluxes with measurements made by various WHOI research buoys confirm the suggestion of Josey et al. (1999) that spatially fixed parameter adjustments lead to poorer agreement with the buoys than was found to be the case with the original SOC fluxes. This result indicates that spatially dependent adjustments of the free parameters in the inverse analysis are necessary in order to obtain a solution which is satisfactory in the sense that it meets the three requirements listed above.

Item Type: Publication - Report (Technical Report)
Programmes: NOC Programmes
Date made live: 31 Jul 2013 13:56 +0 (UTC)
URI: http://nora.nerc.ac.uk/id/eprint/502826

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