A new method for forming approximately neutral surfaces

[摘要] We introduce a simple algorithm to improve existing density surfaces toensure that the resulting surfaces are as close to neutral as possible. Thismeans the slopes at any point on the surfaces are close to neutral tangentplanes – the directions along which layered stirring and mixing occurs –minimizing the fictitious diapycnal diffusivity. Inverse techniques andlayered models have been used for decades to understand ocean circulation.The most-used density surfaces are potential density or neutral densitysurfaces. Both these density surfaces and all others produce a fictitiousdiapycnal diffusivity to some degree due to the helical nature of neutraltrajectories – with the magnitude of this artificial diffusivity in somecases being larger than the values measured in the ocean. Here we show howthis error can be reduced by up to four orders of magnitude and thereforebecomes insignificant compared to measured values, thus providing surfaceswhich would produce more accurate results when used for inverse techniques.

[学科分类] 海洋学与技术