Title

Baltic Sea Subsurface Temperature trend from Reanalysis

Alternate title

BALTIC_OMI_TEMPSAL_Ttz_trend

Date (Creation)

2019-11-28

Edition

3.4

Edition date

2024-11-26

Citation identifier

a78600a4-a280-47b5-8ddd-0dc8b5e9c9d9

Abstract

'''DEFINITION'''

The subsurface temperature trends have been derived from regional reanalysis results for the Baltic Sea (product references BALTICSEA_MULTIYEAR_PHY_003_011). Horizontal averaging has been done over the Baltic Sea domain (13 °E - 31 °E and 53 °N - 66 °N; excluding the Skagerrak strait). The temperature trend has been obtained through a linear fit for each time series of horizontally averaged annual temperature and at each depth level.

'''CONTEXT'''

The Baltic Sea is a semi-enclosed sea in North-Eastern Europe. The temperature of the upper mixed layer of the Baltic Sea is characterised by a strong seasonal cycle driven by the annual course of solar radiation (Leppäranta and Myrberg, 2008). The maximum water temperatures in the upper layer are reached in July and August and the minimum during February, when the Baltic Sea becomes partially frozen (CMEMS OMI Baltic Sea Sea Ice Extent, CMEMS OMI Baltic Sea Sea Ice Volume). Seasonal thermocline, developing in the depth range of 10-30 m in spring, reaches its maximum strength in summer and is eroded in autumn. During autumn and winter the Baltic Sea is thermally mixed down to the permanent halocline in the depth range of 60-80 metres (Matthäus, 1984). The 20–50 m thick cold intermediate layer forms below the upper mixed layer in March and is observed until October within the 15-65 m depth range (Chubarenko and Stepanova, 2018; Liblik and Lips, 2011). The deep layers of the Baltic Sea are disconnected from the ventilated upper ocean layers, and temperature variations are predominantly driven by mixing processes and horizontal advection. A warming trend of the sea surface waters is positively correlated with the increasing trend of diffuse attenuation of light (Kd490) and satellite-detected chlorophyll concentration (Kahru et al., 2016). Temperature increase in the water column could accelerate oxygen consumption during organic matter oxidation (Savchuk, 2018).

'''KEY FINDINGS'''

Analysis of subsurface temperatures from 1993 to 2023 indicates that the Baltic Sea is experiencing warming across all depth intervals. The temperature trend in the upper mixed layer (0-25 m) is approximately 0.055 °C/year, decreasing to 0.045 °C/year within the seasonal thermocline layer. A peak temperature trend of 0.065 °C/year is observed at a depth of 70 m, aligning with the base of the cold intermediate layer. Beyond this depth, the trend stabilizes, closely matching the 0.065 °C/year value. At a 95% confidence level, it can be stated that the Baltic Sea's warming is consistent with depth, averaging around 0.06 °C/year. Notably, recent trends show a significant increase; for instance, Savchuk's 2018 measurements indicate an average temperature trend of 0.04 °C/year in the Baltic Proper's deep layers (>60m) from 1979 to 2016.

'''DOI (product):'''

https://doi.org/10.48670/moi-00208

Credit

E.U. Copernicus Marine Service Information

Point of contact

Organisation name	Individual name	Electronic mail address	Role
BAL-SMHI-NORRKOPING-SE			Production Unit

Maintenance and update frequency

Annually

Other

P0M0D0H/P0M0D0H

Maintenance note

N/A

GEMET - INSPIRE themes, version 1.0

• Oceanographic geographical features

Discipline

• numerical-model

Climate and Forecast Standard Names

• sea_water_temperature_trend
• confidence interval

Temporal scale

• multi-year

Area of benefit

• coastal-marine-environment
• marine-safety
• marine-resources
• weather-climate-and-seasonal-forecasting

Reference Geographical Areas

• baltic-sea

Processing level

• N/A

Model assimilation

• Not Applicable

Use limitation

See Copernicus Marine Environment Monitoring Service Data commitments and licence at: http://marine.copernicus.eu/web/27-service-commitments-and-licence.php

Access constraints

Other restrictions

Use constraints

License

Other legal constraints

No limitations on public access

Aggregate Datasetindentifier

aebb5c37-8308-48ae-a126-2b234015e4c0

Association Type

Cross reference

Initiative Type

Document

Aggregate Datasetindentifier

b5d58b7c-5932-4d11-86d3-89f7c50fcad5

Association Type

Cross reference

Initiative Type

Document

Aggregate Datasetindentifier

441e5871-fcfc-4d40-8aaf-fdfcd58f3634

Association Type

Cross reference

Initiative Type

Document

Title

Chubarenko, I., Stepanova, N. 2018. Cold intermediate layer of the Baltic Sea: Hypothesis of the formation of its core. Progress in Oceanography, 167, 1-10, doi: 10.1016/j.pocean.2018.06.012

Date (Creation)

2019-05-08

Association Type

Cross reference

Initiative Type

Reference

Title

Kahru, M., Elmgren, R., and Savchuk, O. P. 2016. Changing seasonality of the Baltic Sea. Biogeosciences 13, 1009–1018. doi: 10.5194/bg-13-1009-2016

Date (Creation)

2019-05-08

Association Type

Cross reference

Initiative Type

Reference

Title

Leppäranta, M., Myrberg, K. 2008. Physical Oceanography of the Baltic Sea. Springer, Praxis Publishing, Chichester, UK, pp. 370

Date (Creation)

2019-05-08

Association Type

Cross reference

Initiative Type

Reference

Title

Liblik, T., Lips, U. 2011. Characteristics and variability of the vertical thermohaline structure in the Gulf of Finland in summer. Boreal Environment Research, 16, 73-83.

Date (Creation)

2019-05-08

Association Type

Cross reference

Initiative Type

Reference

Title

Matthäus W, 1984, Climatic and seasonal variability of oceanological parameters in the Baltic Sea, Beitr. Meereskund, 51, 29–49.

Date (Creation)

2019-05-08

Association Type

Cross reference

Initiative Type

Reference

Title

Savchuk, .P. 2018. Large-Scale Nutrient Dynamics in the Baltic Sea, 1970–2016. Frontiers in Marine Science, 5:95, doi: 10.3389/fmars.2018.00095

Date (Creation)

2019-05-08

Association Type

Cross reference

Initiative Type

Reference

Language

eng

Topic category

• Oceans

Description

bounding box

Begin date

1993-01-01

End date

2021-12-31

Supplemental Information

display priority: 53800

Codespace

EPSG

Number of dimensions

2

Dimension name

Row

Dimension name

Column

Cell geometry

Area

Transformation parameter availability

Distribution format

Name	Version
NetCDF-4

OnLine resource

Protocol	Linkage	Name
WWW:STAC	https://stac.marine.copernicus.eu/metadata/BALTIC_OMI_TEMPSAL_Ttz_trend/baltic_omi_tempsal_Ttz_area_averaged_trend_202311/dataset.stac.json	baltic_omi_tempsal_Ttz_area_averaged_trend
OGC:WMTS	https://wmts.marine.copernicus.eu/teroWmts/BALTIC_OMI_TEMPSAL_Ttz_trend/baltic_omi_tempsal_Ttz_area_averaged_trend_202311?service=WTMS&request=GetCapabilities	baltic_omi_tempsal_Ttz_area_averaged_trend

Hierarchy level

Series

Statement

The myOcean products depends on other products for production or validation. The detailed list of dependencies is given in ISO19115's aggregationInfo (ISO19139 Xpath = "gmd:MD_Metadata/gmd:identificationInfo/gmd:aggregationInfo[./gmd:MD_AggregateInformation/gmd:initiativeType/gmd:DS_InitiativeTypeCode/@codeListValue='upstream-validation' or 'upstream-production']")

Attribute description

observation

Content type

Physical measurement

Descriptor

vertical level number: 1

Descriptor

temporal resolution: daily mean

Included with dataset

Feature types

Profile

Metadata

File identifier

aca35159-2223-444f-b7e9-a8052687ee1f

Metadata language

English

Character set

UTF8

Hierarchy level

Series

Hierarchy level name

Copernicus Marine Service product specification

Date stamp

2025-04-11T12:52:46.907656Z

Metadata standard name

ISO 19139, MyOcean profile

Metadata standard version

0.2

Metadata author

Organisation name	Individual name	Electronic mail address	Role
CMEMS		servicedesk.cmems@mercator-ocean.eu	Local service desk