Computation of a new mean dynamic topography for the Mediterranean Sea from model outputs, altimeter measurements and oceanographic in situ data

[摘要] The accurate knowledge of the ocean's mean dynamic topography (MDT) is acrucial issue for a number of oceanographic applications and, in some areas ofthe Mediterranean Sea, important limitations have been found pointing to theneed of an upgrade. We present a newMDTthat wascomputed for the Mediterranean Sea. It profits from improvements madepossible by the use of extended data sets and refined processing. The updateddata set spans the 1993–2012 period and consists ofdrifter velocities,altimetry data, hydrological profiles and model data. The methodology issimilar to the previous MDT by Rio et al. (2007). However, in Rio et al. (2007)no hydrological profiles had been taken into account. This required thedevelopment of dedicated processing. A number of sensitivity studies havebeen carried out to obtain the most accurate MDT as possible. The mainresults from these sensitivity studies are the following: moderate impact tothe choice of correlation scales but almost negligible sensitivity to thechoice of the first guess (model solution). A systematic external validationto independent data has been made to evaluate the performance of the new MDT.Compared to previous versions, SMDT-MED-2014 (Synthetic Mean Dynamic Topographyof the MEDiterranean sea) features shorter-scalestructures, which results in an altimeter velocity variance closer to theobserved velocity variance and, at the same time, gives better Taylor skills.

[学科分类] 海洋学与技术