@SEA Data Coverage & Limitations
Overview
The @SEA report contains high-quality data from numerous acknowledged and credible sources worldwide. Where possible global data sources were selected to provide homogenous coverage for the whole globe or at least as much as feasible within different topics. Below are listed main geographical limitations on data availability.
Geo-Administrative Information
The geo-administrative information covers national borders on land and at sea, special maritime zones of national influence like the 12 and 24 nautical miles zones and the continental shelf if such is claimed by the country within which the location of interest is placed. The available data covers all continents at full latitude range (-90 to +90).
Major Seismic Faults
The major seismic faults data cover all continents at full latitude range (-90 to +90) as published in 2007 by the Geological Survey of Canada.
Satellite Time Series
Satellite images are supplied for on-shore locations or marine locations within 25km from the shore line. Data availability is further restricted to latitude range between -56° and 72°. For some locations within the latitude range between 72° and 84° data may be available. The satellite time series covers the last 12 months and is divided into 4 seasons (Jan-Feb, Apr-May, Jul-Aug, Oct-Nov) to visualize site changes due to changing seasons. The four most resent completed and processed seasons are used. The images were acquired by the Sentinel-2 satellites with 10m/pixel using a multispectral imaging camera. The different image bands are combined into true colour images presented in this report. Since clouds present an impenetrable obstruction, only images with low cloud cover (<5% of tile area contains clouds) are used. In rare circumstances when the whole season didn’t yield such image for a given location, such season will be missing from this report.
Elevation Model
Elevation models are called Digital Surface Models (DSM) if they represent elevation of earth’s surface above the sea level, whereas for depths below the sea level, elevation model is called Bathymetry. For the purpose of this report, both models are engineered together for coastal locations.
The bathometric data originates from the most recent release by GEBCO (General Bathymetric Charts of Oceans, 2022) offering water depth values on a grid with 15” (arc-second) resolution. Generally, the depth data is in meters [m] relative to the Geoid (mean sea level), however, it is noticed that some shallow coastal areas might be offset by a local datum.
The DSM data was collected by JAXA (Japan Aerospace Exploration Agency) using Advanced Land Observing Satellite (ALOS) equipped with optical Panchromatic Remote-sensing Instrument for Stereo Mapping (PRISM). The ALOS data was averaged within 1” grid pixels corresponding to a horizontal resolution of 30m.
Sub- and above-ice elevation is presented within latitude range -80 to +80 degrees.
Climate Characteristics
The combination of heterogeneous ground and satellite observation through numerical models have been shown to be on average in very good agreement with in-situ measurements. Nevertheless, the values remain time and space averages (hourly average over 0.25o x 0.25o area) and caution should be exercised when comparing with in-situ measurements for a specific location. The CDS datasets, used for @SEA reports are assessed by the Evaluation and Quality Control (EQC) function of C3S independently of the data supplier. EQC encompasses a framework of processes aimed to assure technical and scientific quality harmonized across all dataset types available through the CDS. During the EQC process, the documentation provided with the dataset is scrutinized and data are checked for usability and reliability. The model and observations are unbiased and their errors follow Gaussian distributions and as long as the observations are homogeneous in space and time, the analysis error is the smallest in the middle of the assimilation window.
The data covers the whole globe on land and at sea.
Sea and Ocean Characteristics
The data covers off-shore areas within the latitude band -80 to +80 degrees at resolution of 0.0833 degrees (approximately 9km). The extremely shallow near coast locations might be excluded due to the unreliability of the measurements in such areas. Also reports for some near-shore land locations may include this section if they fall within a grid including deeper waters too.
The report data is based on CMEMS system. A model component is the NEMO platform driven at surface by ECMWF ERA-Interim then ERA5 reanalysis for recent years. Observations are assimilated by means of a reduced-order Kalman filter.
Sea Ice properties
This section is only included for locations where sea ice is regularly detected.
Sea State (Waves)
The data covers off-shore areas within the latitude band -80 to +80 degrees . The extremely shallow near coast locations might be excluded due to the unreliability of the measurements in such areas. Also reports for some near-shore land locations may include this section if they fall within a grid including deeper waters too. To provide the best accuracy and spatial resolution, this report utilizes the Global Ocean Waves Reanalysis, Waverys product from CMEMS which provides 3 hourly data gridded with a spatial resolution of 0.2o x 0.2o . The Global Ocean Waves Reanalysis is based on MFWAM model coupled with GLORY12 physical ocean reanalysis which assimilates historic observational data.
Vessel Density
It is based on over one billion AIS messages from over 50,000 distinct vessels, covering the period from January 1, 2015, to April 18, 2020. The AIS traffic data is mainly from commercial vessels such as dry and wet bulk vessels, containers, oil and gas tankers, large fishing, and passenger boats. Small service boats such as tugboats and barges or small fishing vessels don’t usually carry IMO registration and are not part of this dataset. Vessel density coverage ranges between -72° and 83° latitudes and includes inland waterways.
Protected and Designated Areas
Protected areas data covers United States, Australia, Albania, Austria, Bosnia and Herzegovina, Belgium, Bulgaria, Switzerland, Cyprus, Czech Republic, Germany, Denmark, Estonia, Greece, Spain, Finland, France, Croatia, Hungary, Ireland, Iceland, Italy, Liechtenstein, Lithuania, Luxembourg, Latvia, Montenegro, North Macedonia, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Sweden, Slovenia, Slovakia, Kosovo
Critical Habitats
Habitat and species data covers United States, Australia, United Kingdom, Norway, Russian Federation, Ukraine, Belarus, Georgia, Armenia, Andorra, Albania, Bosnia and Herzegovina, Azerbaijan, Switzerland, Montenegro, Iceland, Moldova, North Macedonia, Serbia, Liechtenstein, Latvia, Austria, Germany, Lithuania, Poland, Hungary, Estonia, Slovakia, Portugal, Denmark, Slovenia, Romania, Sweden, Croatia, Cyprus, Finland, Bulgaria, Czech Republic, Spain, France, Greece, Italy, Luxembourg, Netherlands, Belgium, Ireland, Malta
