Towards closure of regional heat budgets in the North Atlantic using Argo floats and surface flux datasets

[摘要] The upper ocean heat budget (0–300 m) of the North Atlantic from20°–60° N is investigated using data from Argo profiling floats for1999–2005 and the NCEP/NCAR and NOC surface flux datasets. Estimates of thedifferent terms in the budget (heat storage, advection, diffusion andsurface exchange) are obtained using the methodology developed by Hadfieldet al. (2007a, b). The method includes optimal interpolation of theindividual profiles to produce gridded fields with error estimates at a10°×10° grid box resolution. Closure of the heat budget isobtained within the error estimates for some regions – particularly theeastern subtropical Atlantic – but not for those boxes that include the GulfStream. Over the whole range considered, closure is obtained for 13 (9) outof 20 boxes with the NOC (NCEP/NCAR) surface fluxes. The seasonal heatbudget at 20–30° N, 35–25° W is considered in detail. Here, the NCEPbased budget has an annual mean residual of −55±35 Wm⁻²compared with a NOC based value of −4±35 Wm⁻². For this box,the net heat divergence of 36 Wm⁻² (Ekman=−4 Wm⁻²,geostrophic=11 Wm⁻², diffusion=29 Wm⁻²) offsets the net heatingof 32 Wm⁻² from the NOC surface heat fluxes. The results in this boxare consistent with an earlier evaluation of the fluxes using measurementsfrom research buoys in the subduction array which revealed biases in NCEPbut good agreement of the buoy values with the NOC fields.

[学科分类] 海洋学与技术