Shom is the national referent for the level of the sea in situ on all areas under French jurisdiction. In this capacity, he assures under the acronym REFMAR different coordination functions in the collection and dissemination of public data related to water level observations, in order to promote their use in multiple applications within the framework of international recommendations.

Shom manages a network of permanent digital coastal tide-gauges on French coasts: the RONIM Sea Level Observation Network. Most tide-gauge observatories are partnered with one or more local partners.<br /><br /> Four main types of data are available for download:<br /> - “Raw high frequency" data: raw observations neither validated nor evaluated, obtained directly from the sensor. 1-minute measurement; integration time 15 seconds (on the minute); sampling period: 1 second.<br /><br /> - "Raw non-real time" data: raw observations neither validated nor evaluated, obtained directly from the sensor. 10-minute measurement; integration time 121 seconds (around every 10 minutes); sampling period: 1 second.<br /><br /> - "Validated non-real time" data: observations checked and validated by Shom from the "Raw non-real time" data. 10-minute measurement; integration time 121 seconds (around every 10 minutes); sampling period: 1 second.<br /><br /> - "Validated hourly" data: observations checked and validated by Shom, generated from "Validated non-real time" data. Hourly measurement obtained from the Vondrak filter with triangular weighting. The hourly height cannot be calculated in the event of an observation gap greater than 1.5 hours.

Grid processed for the purpose of the HR DTMs layer of EMODnet Bathymetry HRSM, October 2018

Conversion into the EMODnet format of the published grid for the Capbreton Canyon in 2007: http://dx.doi.org/10.12770/72e2f750-c255-11df-a9b6-005056987263

Satellite altimetry missions provide a quasi-global synoptic view of sea level over more than 25 years. The satellite altimetry constellation is used to build sea level maps and regional sea level indicators such as trends and accelerations. Estimating realistic uncertainties on these quantities is crucial to address some current climate science questions such as climate change detection and attribution or regional sea level budget closure for example. Previous studies have estimated the uncertainty for the global mean sea level (GMSL), but no uncertainty information is available at regional scales. In this study we estimate a regional satellite altimetry error budget and use it to derive maps of confidence intervals for local sea rise rates and accelerations. We analyze 27 years of satellite altimetry maps and derive the satellite altimetry error variance-covariance matrix at each grid point, prior to the estimation of confidence intervals on local trends and accelerations at the 90% confidence level using extended least squares estimators. Over 1993–2019, we find that the average local sea level trend uncertainty is 0.83 mm.yr-1 with local values ranging from 0.78 to 1.22 mm.yr-1. For accelerations, uncertainties range from 0.057 to 0.12 mm.yr-2, with a mean value of 0.063 mm.yr-2.   Change history: - 2020/07/08: initial dataset submission over 1993-2018 - 2020/10/21: 1993-2019 update and addition of error levels

Shom uses HYCOM 3D (Hybrid Coordinate Ocean Model) digital models to model changes to the ocean environment (currents, temperature, salinity, water depth). These HYCOM 3D models include a scalable (space and time) vertical grid, which is particularly suitable for the coastal regions and physical phenomena modelled (particularly the transition from a deep sea zone to the continental shelf, and the presence of frontal zones). These models were adapted to coastal models at Shom, particularly by integrating tides and the effects of rivers. These models focus on changes and variability in the different physical processes affecting coastal areas (continental shelves and slopes), such as tidal fronts, river plumes, tides and internal waves, upwelling and the dynamics of the mixed layer at an hourly frequency and with high spatial resolution (1/60 deg for the Biscay Channel model).

The DTM is produced with Kongsberg multibeam echosounder survey, acquired in March 2020 by Marine Research Ltd. The resolution is 1/256 arc-minutes (~7.2m). It is located at Tuzla, Romania, on the coastal region of the Black Sea. Depths are referenced to the Local Sea Level - Marea Neagra 1975 and the coordinates are expressed into the WGS84 reference frame.

The DTM is produced with Kongsberg multibeam echosounder survey, acquired in March 2020 by Marine Research Ltd. The resolution is 1/256 arc-minutes (~7.2m). It is located at Mangalia Harbour, Romania, on the coastal region of the Black Sea. Depths are referenced to the Local Sea Level - Marea Neagra 1975 and the coordinates are expressed into the WGS84 reference frame.

The DTM is produced with Kongsberg multibeam echosounder survey, acquired in March 2020 by Marine Research Ltd. The resolution is 1/256 arc-minutes (~7.2m). It is located at 23 August, Romania, on the coastal region of the Black Sea. Depths are referenced to the Local Sea Level - Marea Neagra 1975 and the coordinates are expressed into the WGS84 reference frame.