LanderPick, a remote operated trawled vehicle to cost-effectively deploy and recover lightweight oceanographic landers

LanderPick project consists of the design of a cost-efective system for deploying and picking-up lightweight oceanographic landers, not provided with recovery elements, but having a structure that facilitates their hitching (a capture mesh). The LanderPick vehicle prototype is a Remote Operated Trawled Vehicle (ROTV) specifcally designed to operate a mechanical release that allows the placement at the sea bottom of landers carried as a payload, as well as their recovery by means of a triple hook. The vehicle mostly depends on the ship positioning system but has small propellers to aid in the fnal precision approach manoeuvres. First sea trials of the system in April 2021 are described.Peer Reviewe

Strong-mixing induced deep ocean heat uptake events in the North Atlantic.

The deceleration of the upper ocean heat storage during the last decade has resulted in an active search for the ’missing heat’ in the deep ocean. Modeling work has provided new insights into the role of the central Pacific Ocean on the present hiatus in global warming and the efficient transfer of heat to the deep ocean, but recent studies have highlighted also the large contribution of the North Atlantic basin to these processes, mainly based on ocean observations. The deep ocean heat uptake (below 300 m) in the North Atlantic is not confined to the subpolar gyre region but extends to mid-latitudes of the Eastern North Atlantic (ENA), requiring an additional process for its explanation other than deep convection considered until now. Here, using oceanographic in-situ data, we describe a mechanism of heat and salt injection to the deep ocean after years of warming and saltening at the surface occurred both in regions of mode (43º-48ºN) and deep water (74º-76ºN) formation in the ENA. The mechanism, although punctual meditated by strong winter mixing events, is between 2 and 6 times higher than the 2000-2010 ocean heat uptake at depths of mode (300-700m) and deep water (>2000m) formation, contributing significantly to the observed deep ocean heat uptake in the North Atlantic. Nutrient, hydrographic and reanalysis data indicate that the strong mixing-induced deep ocean heat uptake events at areas of mode and deep water formation in the North Atlantic are connected through the northward propagation of salty ENA mode waters triggered by the contraction of the subpolar gyre reinforced by the occurrences of blocking anomalies in the ENA. Such connection is not unique of the last decade but observed also during the 1960s. Natural climate variability seems the ultimate driver of the strong mixing-induced deep ocean heat uptake events, although the anthropogenic global warming and its forcing on the Arctic sea-ice retreat and frequency of extreme weather events could modify their effects.0,000

Observation of an abrupt disruption of the long-term warming trend at the Balearic Sea, Western Mediterranean Sea, in summer 2005

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Thermohaline evolution of the Western Mediterranean Deep Waters since 2005: diffusive stages and interannual renewal injections

A large production of anomalous dense water in the northwestern Mediterranean Sea during winter 2005 led to a widespread abrupt shift in Western Mediterranean deep waters characteristics. This new configuration, the so-called Western Mediterranean Transition (WMT), involved a complex thermohaline structure that was tracked over time through a deep hydrographic station located NE of Minorca Island, sampled 37 times between 2004 and 2017. In this study, the thermohaline evolution of the WMT signal is analyzed in detail. Using a 1-D diffusion model sensitive to double-diffusive mixing phenomena, the contribution to the heat and salt budgets of the deep Western Mediterranean in terms of ventilation and diffusive transference from the intermediate layers above is disentangled. Results show distinct stages in the evolution of the deep waters, driven by background diffusion and intermittent injections of new waters. The progression of a multilayered structure in the deep ocean is well represented through existing parameterizations of salt fingering and diffusive layering processes and makes it possible to infer an independent estimate of regional background diffusivity consistent with current knowledge. Overall, the deep layers of the Western Mediterranean underwent substantial warming (0.059 °C) and salt increase (0.021) between 2004 and 2017, mostly dominated by injections of dense waters in the 2005–2006 and 2011–2013 periods. Thus, within the WMT period, heat uptake rate in the deep Western Mediterranean was substantially higher than that of the intermediate levels in the global ocean.CTM2014‐54374‐R / BES‐2015‐074316Versión del editor3,17

Morphological features and associated bottom-current dynamics in the Le Danois Bank region (southern Bay of Biscay, NE Atlantic):A model in a topographically constrained small basin

17 pages, 11 figures, 1 appendixThe present-day morphology of the Le Danois Bank region has been investigated based on bathymetric and high to ultra-high resolution seismic reflection data. The involved bottom-current processes are associated with the Eastern North Atlantic Central Water, the Atlantic Mediterranean Water and the Labrador Sea Water. Sediments originating from various canyon systems along the Cantabrian Margin and the Asturias continental shelf are transported by downslope and alongslope processes towards the Le Danois intraslope basin. The background flow velocities of bottom currents are all below the threshold (8–10 cm/s) of generating plastered and mounded geometries of contourite drifts. However, bottom currents are locally accelerated (up to 25 cm/s) due to the presence of the Le Danois Bank and the Vizco High, creating a furrow and three moats and generating six plastered drifts, three elongated mounded and separated drifts at different depth intervals. The extension and distribution of the drifts are controlled by slope morphology and/or bottom current velocities. Unlike contourite drifts along other continental slopes, a single contourite drift (the Gijón Drift) with a lateral variation in drift geometry and internal structure indicates the interaction of bottom currents with different flow dynamics. Additionally, scouring of active bottom currents and rapid sedimentation rate of contourite drifts may be at the origin of slope instability events. Besides contourite drifts, internal waves may have induced the formation of sediment waves. In the Le Danois intraslope basin, multiple sedimentary processes work together and shape the present-day seafloor. Bottom currents are focused due to deflection on complex topographical obstacles within a relatively small basin setting, and create a wide variety of sedimentary features, including contourite drifts. The resulting sedimentary features thus have more frequent lateral variations, a feature typical for topographically constrained small basinsThis study was carried out within the framework of a Chinese Scholarship Council “CSC Grant” (201506410062). The research was conducted in collaboration with “The Drifters Research Group” of the Royal Holloway University of London (UK) and it is related to the projects CTM 2012-39599-C03, CGL2016-80445-R, and CTM2016-75129-C3-1-R. [...] These research campaigns framed within the ECOMARG (REN2002-00916/MAR) and MARCONI (REN2001-1734 C03-01/M) projects. This study also builds upon achievements of project ESF Euromargins MOUNDFORCE, EC FP5 RTN EURODOM and EC FP6 HERMES (GOCE-CT-2005-511234-1)Peer Reviewe