Here, you will find some cases studies assessed in collaboration with various institutes.
Underwater glider observations and modeling of an abrupt mixing event in the upper ocean
Simón Ruiz(1), Lionel Renault(2) , Bartolomé Garau(2), Joaquín Tintoré(1,2)
1 IMEDEA (CSIC-UIB), Miquel Marqués 21, 07190, Esporles, Balearic Islands, Spain
2 ICTS SOCIB, Balearic Islands Coastal Observing and Forecasting System Parc Bit, Naorte, Bloc A P3, 07121, Palma de Mallorca, Balearic Islands, Spain
Abstract: An abrupt mixing event in the upper ocean is investigated in the Northwestern Mediterranean Sea using gliders, a new ocean monitoring technology, combined with regional atmospheric model outputs and mooring data. Intense winds (up to 20 m s−1) and buoyancy forcing during December 2009 induced strong vertical mixing of the upper ocean layer in the Balearic Sea. High-resolution data from a coastal glider reveal a surface cooling of near 2 °C and the deepening of the Mixed Layer Depth (MLD) by more than 40 meters in the center of the basin. Comparisons between glider and ship-emulated sections of hydrographic profiles show that the glider data make visible the small-scale spatial variability of the MLD. The heat content released to the atmosphere by the upper ocean during this mixing event exceeds 1000 W m−2. A simulation from the Weather Research and Forecasting model reports values consistent with these observations. Additionally the atmospheric numerical simulation shows the development and evolution of a cyclone located south of the Balearic Islands. This cyclone is likely to be responsible for the wind intensification and the consequent air-sea energy exchanges that occurred in the study area during this period.
Citation: Ruiz, S., L. Renault, B. Garau, and J. Tintoré (2012), Underwater glider observations and modeling of an abrupt mixing event in the upper ocean, Geophys. Res. Lett., 39, L01603, doi:10.1029/2011GL050078.
Assessment of wind models around the Balearic Islands for operational wave forecastSurface Gravity Waves
S. Ponce de León(1), A. Orfila(1), L. Gómez-Pujol(2), L. Renault(2), G. Vizoso(1), J. Tintoré(1,2)
(2) ICTS SOCIB, Balearic Islands Coastal Observing and Forecasting System Parc Bit, Naorte, Bloc A P3, 07121, Palma de Mallorca, Balearic Islands, Spain
A wave hindcast in the Western Mediterranean Sea is carried out in order to assess the performance of three atmospheric models in providing the forcing for a third generation wave model. The wind models have been used as forcing fields for the generation of waves and the resulting significant wave height time history compared with four buoys around the Balearic Islands. Two different wave-model grid resolutions are used to get the wave field in the entire Mediterranean and around the Balearic Islands. The present application was performed for three months: November 2008 and for July and August 2009. Results indicate that all data sources provide good forcing for operational wave forecast at large scales (wind forecast with grid resolution of 30 and 25 km). Near the coast or at the lee of islands, resolving small scale topographical features result in a better forecast of wave fields. However, for the area studied,the atmospheric model that better represents summer and winter conditions is hourly WRF at 1.5 km resolution.
Citation: S. Ponce de León, A. Orfila, L. Gómez-Pujol, L. Renault, G. Vizoso, J. Tintoré, Assessment of wind models around the Balearic Islands for operational wave forecast, Applied Ocean Research, Volume 34, January 2012, Pages 1-9, ISSN 0141-1187, 10.1016/j.apor.2011.09.001.
Subsurface small scale eddy dynamics from multi-sensor observations and modelling
Bouffard, J; Renault, L; Ruiz, S; Pascual, A; Dufau, C; Tintoré, J;
The study of mesoscale and submesoscale [hereafter (sub)mesoscale] hydrodynamic features is essential for understanding thermal and biogeochemical exchanges between coastal areas and the open ocean. In this context, a glider mission was conducted in August 2008, closely co-located and almost simultaneously launched with a JASON 2 altimetric pass, to fully characterize the currents associated with regional (sub)mesoscale processes regularly observed to the north of Mallorca (Mediterranean Sea). A synoptic view from satellite remote-sensing fields, before and during the glider mission, provided a descriptive picture of the main surface dynamics at the Balearic Basin scale. To quantify the absolute surface geostrophic currents, the coastal altimetry-derived current computation was improved and cross-compared with its equivalent derived from glider measurements. Model simulations were then validated both qualitatively and statistically with the multi-sensor observations. The combined use of modeling and multi-sensor observational data reveals the baroclinic structure of the Balearic Current and the Northern Current and a small-scale anticyclonic eddy observed northeast of the Mallorca coast (current ∼ 15 cm/s, <30 km in extent and >180 m deep). This mesoscale structure, partially intercepted by the glider and along-track altimetric measurements, is marked by relatively strong salinity gradients and not, as is more typical, temperature gradients. Finally, the use of the validated model simulation also shows that the geostrophic component of this small-scale eddy is controlled by sub-surface salinity gradients. We hypothesize that this structure contains recently modified Atlantic water arriving from the strait of Ibiza due to a northerly wind, which strengthens the northward geostrophic circulation.
Citation: J. Bouffard, L. Renault, S. Ruiz, A. Pascual, C. Dufau, J. Tintoré (2012), Sub-surface small-scale eddy dynamics from multi-sensor observations and modeling, Progress in Oceanography, Available online 20 July 2012, ISSN 0079-6611, 10.1016/j.pocean.2012.06.007.
Autonomous underwater gliders monitoring variability at "choke points" in our ocean system: A case study in the Western Mediterranean Sea.
Heslop, E. E., S. Ruiz, J. T. Allen, J. L. Lopez-Jurado, L. Renault, and J. Tintore
Recent data from an autonomous ocean glider in the Ibiza Channel (Western Mediterranean Sea) describe variations in the transport volumes of water over timescales of days-weeks, as large as those previously only identifiable as seasonal or eddy driven. High frequency variation in transports of water masses has critical implications for ocean forecasting. Three potential modes of transport are proposed, which have the potential to simplify the previously observed complex pattern of flows. Restricted 'choke points' between ocean basins are critical locations to monitor water transport variability; the Ibiza Channel is one such 'choke point', where variation in the transports of water masses are known to affect the spawning grounds of commercially important fish stocks.
Citation: (2012), Autonomous underwater gliders monitoring variability at "choke points" in our ocean system: A case study in the Western Mediterranean Sea., Geophys. Res. Lett., doi:10.1029/2012GL053717, in press.
Operational evaluation of the Mediterranean Monitoring and Forecasting Centre products: implementation and results
A web-based validation platform has been developed at the Istituto Nazionale di Geofisica e Vulcanologia (INGV) for the Near Real Time validation of the MyOcean-Mediterranean Monitoring and Forecasting Centre products (Med-MFC).
A network for the collection of the in-situ observations, the nested sub-basin forecasting systems model data (provided by the partners of the Mediterranean Operational Oceanography Network, MOON) and the Sea Surface Temperature (SST) satellite data has been developed and is updated every day with the new available data. The network collects temperature, salinity, currents and sea level data. The validation of the biogeochemical forecast products is done by use of ocean colour satellite data produced for the Mediterranean Sea.
All the data are organized in an ad hoc database interfaced with a dedicated software which allows interactive visualizations and statistics (CalVal SW). This tool allows to evaluate NRT products by comparison with independent observations for the first time.
The heterogeneous distribution and the scarcity of moored observations reflect with large areas uncovered with measurements. Nevertheless, the evaluation of the forecast at the locations of observations could be very useful to discover sub-regions where the model performances can be improved, thus yielding an important complement to the basin-mean statistics regularly calculated for the Mediterranean MFC products using semi-independent observations.