Improving the thermocline calculation over the global ocean

Type Article
Acceptance Date 2022-08-29 IN PRESS
Language English
Author(s) Romero EmmanuelORCID1, Tenorio-Fernandez Leonardo2, Portela EstherORCID3, 4, Montes-Aréchiga Jorge5, Sánchez-Velasco LauraORCID1
Affiliation(s) 1 : Instituto Politécnico Nacional–Centro Interdisciplinario de Ciencias Marinas (IPN-CICIMAR), Departamento de Oceanología, Av. IPN s/n, La Paz, B.C.S., 23096, México
2 : CONACyT-Instituto Politécnico Nacional-Centro Interdisciplinario de Ciencias Marinas (IPN-CICIMAR), Av. IPN s/n, La Paz, B.C.S, 23096, México
3 : Institute for Marine and Antarctic Studies, University of Tasmania, Hobart 7001, Australia
4 : Univ. Brest, Laboratoire d’Océanographie Physique et Spatiale, CNRS, IRD, Ifremer, Plouzané, France
5 : Universidad de Guadalajara, Departamento de Física, Gral. Marcelino García Barragán 1421, Olímpica, 44430 Guadalajara, Jal, México
Source EGUsphere (Copernicus GmbH) In Press
DOI 10.5194/egusphere-2022-788

According to the typical thermal structure of the ocean, the water column can be divided into three layers: the mixing layer, the thermocline and the deep layer. In this study, we provide a new methodology, based on a function adjustment on the temperature profile, to locate the minimum and maximum depths of the thermocline, and therefore its thickness, to separate the water column into layers. We first validated our methodology by comparing the mixed layer depth obtained with the method proposed here with that of two previous studies. Since we found a very good agreement between the three methods we used the function adjustment to compute the monthly climatologies of the mixed layer depth, the maximum depth of the thermocline and the thermocline thickness, throughout the ocean. We also provide an assessment of the regions of the ocean where our adjustment is valid, and consequently the regions where the thermal structure of the ocean follows the three-layer structure. However, there are ocean regions where the water column cannot be separated into three layers due to the dynamic processes that alter it and the major contribution of salinity to stratification. This assessment highlights the limitations of the existing methods to accurately determine the mixed layer depth and the thermocline in oceanic regions that are particularly turbulent as the Southern Ocean and the northern North Atlantic, among others. The method proposed here has shown to be robust and easy to apply, and it can be used in both local and global studies.

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