The dataset made available here is the monthly climatology (i.e. 12 months) of ocean surface Mixed Layer Depth (MLD) over the global ocean, at 1 degree x 1 degree spatial resolution. The climatology is based on about 7.3 million casts/profiles of temperature and salinity measurements made at sea between January 1970 and December 2021. Those profiles data come from the ARGO program and from the NCEI-NOAA World Ocean Database (WOD, Boyer et al. 2018). The MLD is computed on each individual cast/profile using a threshold criterion. The depth of the mixed layer is defined as the shallowest depth where the surface potential density of the profile is superior to a reference value taken close to the surface added with the chosen threshold. Here we take a threshold value for the density of 0.03kg/m3, and a surface reference depth fixed at 10m (de Boyer Montégut et al., 2004). This mixed layer is by definition homogeneous in density (up to 0.03 kg/m3 variations) and can also be called an isopycnal layer. It is especially intended for validation of MLD fields of the Ocean General Circulation Models of the ocean sciences community (e.g. Tréguier et al., 2023, Iovino et al. 2023, using v2022 of this dataset). More information and some other related datasets can be found at : https://cerweb.ifremer.fr/mld (or https://www.umr-lops.fr/en/Data/MLD redirecting to previous page).

This dataset contains OAC-P results from application to Argo data in the World Ocean : - the 2000-2015 climatology of OAC-P results mapped onto a 0.5x0.5 grid with mapping error estimates; - the 2000-2015 probability density function of the permanent pycnocline potential density referenced to the sea surface vs Brunt-Väisälä frequency squared.OAC-P is an "Objective Algorithm for the Characterization of the permanent Pycnocline" developed to characterize subtropical gyre stratification features with both observed and modeled potential density profiles. OAC-P estimates the following properties: - for the permanent pycnocline: depth, upper and lower thicknesses, Brunt-Väisälä frequency squared, potential density, temperature and salinity; - for the surface mode water overlying the permanent pycnocline: depth, Brunt-Väisälä frequency squared, potential density, temperature and salinity. Argo data were download from Coriolis Argo GDAC on February, 8th 2016. Only Argo data with QC=1, 2, 5 or 8 were used.

The upper ocean pycnocline (UOP) monthly climatology is based on the ISAS20 ARGO dataset containing Argo and Deep-Argo temperature and salinity profiles on the period 2002-2020. Regardless of the season, the UOP is defined as the shallowest significant stratification peak captured by the method described in Sérazin et al. (2022), whose detection threshold is proportional to the standard deviation of the stratification profile. The three main characteristics of the UOP are provided -- intensity, depth and thickness -- along with hydrographic variables at the upper and lower edges of the pycnocline, the Turner angle and density ratio at the depth of the UOP. A stratification index (SI) that evaluates the amount of buoyancy required to destratify the upper ocean down to a certain depth, is also included. When evaluated at the bottom of the UOP, this gives the upper ocean stratification index (UOSI) as discussed in Sérazin et al. (2022). Three mixed layer depth variables are also included in this dataset, including the one using the classic density threshold of 0.03 kg.m-3, along with the minimum of these MLD variables. Several statistics of the UOP characteristics and the associated quantities are available in 2°×2° bins for each month of the year, whose results were smoothed using a diffusive gaussian filter with a 500 km scale. UOP characteristics are also available for each profile, with all the profiles sorted in one file per month.

The associated data highlights the spatial influence of the dataset of the type “Visual Observations from an Aerial Platform” from the PELAGIS Observatory. These ranges represent the different areas of study on which the PELAGIS observatory conducted campaigns of visual observations from aerial platforms. Each area of study is associated with at least one campaign, with observers and geographical sectors linked to that campaign. Each sector is associated with bathymetric strips and transects related to each of the strips, with a few exceptions for the Indian Ocean region. Description of fields and values of the attribute tables : (- field name, meaning : value, description of values) - region, area of study specific to the PELAGIS observatory PELAGIS : OI/FRM/ AGFR/SOP/SP, region_lbl - programme, associated programme of which the campaign is a part: REMMOA/PACOMM, REcensement de la Mégafaune Marine par Observation Aérienne/Programme d'Acquisition sur les Oiseaux et Mammifères Marins - idCampagne, abbreviated name of the data collection campaign: OI/SAMM/ ANT/SOP/PF/GUY, Campagne Océan Indien/Suivi Aérien de la Mégafaune Marine/Sud Ouest Pacifique/Polynésie Française/ Guyane française - progress, current state of the campaigns, from collection to scientific optimisation : Preparation/Acquisition/ Analysis/Enhancement, campaign being prepared/under acquisition/being analysed/data enhanced within the context of a scientific publication.

The associated data highlights the sampling programme for the data acquisition campaign of Observation on the Aerial Platform for the SAMM1campaign (Aerial Marine Megafauna Monitoring) conducted by the PELAGIS observatory.