Alternate title

PH_BAL_000l_AVG_HALOCLINE_PT

Date (Publication)

2022-09-15T12:00:00

Citation identifier

Probability that the seafloor is below the halocline in the Baltic - Original point dataset ÔÇô Version 2022

Presentation form

Digital map

Credit

EMODnet broad-scale seabed habitat map for Europe (2022), funded by the European Commission

Credit

DHI, DKBS2, Hydrodynamic Model Setup and Validation, Technical note, DHI, August 2018. Available upon request to the author (see section 'author' in the current metadata)

Status

Completed

Point of contact

Organisation name	Individual name	Electronic mail address	Role
DHI	Poul Hammer	ph@dhigroup.com	Author
Ifremer	Mickaël Vasquez	Mickael.Vasquez@ifremer.fr	Originator
GEUS	Zyad Al-Hamdani	azk@geus.dk	Originator
GEUS	Verner Brandbyge Ernstsen	vbe@geus.dk	Originator

GEMET - INSPIRE themes, version 1.0

• Oceanographic geographical features

Theme

• Halocline

• Picnoclyne

Place

• Baltic Sea

Access constraints

Other restrictions

Other constraints

no limitations to public access

Use constraints

Other restrictions

Other constraints

no conditions to access and use

Use limitation

Product under creative common license CC BY-NC-SA: https://creativecommons.org/licenses/by-nc-sa/4.0/

Use limitation

Citation in maps should be as follows: "Source : EMODnet Seabed Habitats (derived from DHI Hydrodynamic 3D Model DKBS2hd)"

Use limitation

Citation in bibliography should be as follows: "Vasquez, M., et al. EUSeaMap 2023. A European broad-scale seabed habitat map. Technical Report"

Spatial representation type

Vector

Denominator

5

Language

English

Character set

UTF8

Topic category

• Oceans

Begin date

2001-01-01T12:00:00

End date

2020-01-31T12:00:00

Reference system identifier

EPSG / 32633

Topology level

Geometry only

Geometric object type

Point

Distribution format

Name	Version
ESRI Shapefile	1.0

OnLine resource

Protocol	Linkage	Name
WWW:LINK-1.0-http--link	https://files.emodnet-seabedhabitats.eu/data/prob_deep_halocline_nodes.zip	EMODnet Seabed Habitats download

Hierarchy level

Dataset

Statement

The model was run by DHI in August 2022. Based on the model results, the final dataset was produced using the following procedure:

Firstly the Brunt-Vaisala frequency squared (N2 = -g/¤ü┬Àd¤ü/dz, where g is the acceleration due to gravity, ¤ü is local water density as calculated by the hydrodynamic model and z is the vertical distance) was calculated in every model grid point horizontally and vertically for every time step. The Brunt-Vaisala frequency squared represents the strength of the stratification of the water column at a certain location.

Secondly for every time step and for every horizontal grid point, the depth of the vertical maximum Brunt-Vaisala frequency squared was determined ÔÇô this depth is assumed to represent the location of the deep halocline. In order to exclude any transient haloclines in the upper water column, a limit on the halocline depth of 25m was introduced such that only the water column below 25m was considered. Another limitation introduced in the analysis is that N^2 has to be above 0.0005s^-2 before it is accepted. This means that if N^2 at a certain time in a certain horizontal location is below this limit in the whole water column, then no halocline is identified. This lower limit on N^2 was introduced after some trial-and-error, in order to avoid identifying ÔÇÿfalseÔÇÖ haloclines. Notice that this limit is influenced by both physical and model resolution considerations.

Thirdly the annual probability of a certain seabed location being located under the deep halocline was calculated as the amount of time steps where a deep halocline was identified divided by the total number of time steps.

The above procedure has been performed for the years delivered from 2001 to 2020 (incl.).

Metadata

File identifier

9e4edb30-aefb-4551-9c6f-7cf324b4edb3 XML

Metadata language

English

Character set

UTF8

Hierarchy level

Dataset

Date stamp

2022-09-12T14:56:09.194Z

Metadata standard name

ISO 19115:2003/19139

Metadata standard version

1.0

Metadata author

Organisation name	Individual name	Electronic mail address	Role
JNCC	Joint Nature Conservation Committee	emodnetseabedhabitats@jncc.gov.uk	Point of contact