Profiling coastal waters
Lead: HCMR (Monty Priede)
Task 3.3 is distributed into three subtasks dealing with innovative improvement of existing profiling approaches.
SubTask: 3.3.1 Bottom mounted profiling systems (led by IMR): Bottom mounted profiling system offer fully complementary observation systems to JELAB float system, providing long term, repeated profiles at a fixed location, hence capturing key physical or biogeochemical processes at strategic locations.
Subtask a) MASTODON2D. Internal waves are ubiquitous waves (few km wave length, with amplitudes of few to tens meters of isotherms at frequency from few minutes to the tidal frequency (12h)) propagating over hundreds of km in coastal summer stratified seas, hence modifying vertical mixing conditions. Except a few radar images catching the surface signature, internal waves observations require in situ measurements, which are expensive and risky over the shelf and therefore sparse. Mastodon2D is an extension of the Mastodon project which provides time series of bottom temperature with low cost mooring. It will consist in adding a vertical line from the bottom to the near surface, equipped at multiple depths with temperature sensors and will benefit the development of Mastodon for the deployment and recovery phases. The innovation does not lie on the measured parameter (thermistor chains exist for decades) but in the opportunity to multiply moorings due to their low cost (<1000euros, at least 10 time less than conventional thermistor systems) and provide data at high spatial resolution. Developed moorings will be deployed in the JRAP-4 of the WP4.
Subtask b) YOYO trawl-secured profiling system. While MASTODON2D will investigate rapid (down to minutes) processes at given depths, the YOYO project aims at developing an automated system that conducts daily full profiles measuring T, S, Chl fluorescence and oxygen, including quasi real time automatic data transmission for dissemination. However in coastal waters, many areas are in fishing zones where permanent instrumented buoys at the surface can be potentially damaged or removed by fishing boats. Therefore a bottom-mounted vertical profiling system was developed and tested in 50 m water depth without the automated data transfer. This task aims at making the system reliably working in areas with water depths up to 300 meters, where current speed is significantly high (up to 1.2 m/s) and likely impact the profiler motion. The behavior of the floating platform equipped with all environmental sensors and the resistance of the system to drag and drift are the main issues investigated. A YOYO prototype will be tested in the LoVe cable based observatory area (see WP 2) along the Norwegian coast for several months in self-recording mode.
SubTask: 3.3.2 JELAB: Jerico Extended Lagrangian Bio-Geo-profilers (led by HCMR): Argo float technology is well established as a means of recording physical parameters in three dimensions in the open ocean and has been extended to coastal waters and biogeochemical sensors. The objective of JELAB is to expand the capacities of advanced Argo-type floats (e.g.ProvBio, BioArgo and Arvor-Cm) particularly for coastal applications by extending available payload. JELAB will be aimed to increase the instrumentation payload first with a camera system capable of imaging in the water column and on the sea floor. Sea-floor imaging and sensing during benthic parking will add a powerful new dimension to integration of surface to bottom biogeochemical measurements. Owing to a need to operate throughout the Cretan Sea a greater depth rating (2000 m) will be necessary. This extra payload development will be transferred in the near future to other applications such as water sampling. The JELAB floats will be based on commercially available software and hardware. HCMR and Ifremer will jointly contribute to these new developments. Operational performance of JELAB floats will be tested and validated in large-scale basin facilities and at sea.
Deliverable 3.5: Report after development dedicated to profile coastal waters (M38). This report will include the details of MASTODON2D: material, performances, accuracy, test at sea and final cost for possible industrial transfer, including plan designs, and the behavior and robustness of the YOYO system in deep energetic
Deliverable 3.6: Report on the JELAB instrument performance and trials at sea (M40)