Global mean sea water pH

'''DEFINITION'''Ocean acidification is quantified by decreases in pH, which is a measure of acidity: a decrease in pH value means an increase in acidity, that is, acidification. The observed decrease in ocean pH resulting from increasing concentrations of CO2 is an important indicator of global change. The estimate of global mean pH builds on a reconstruction methodology,

• Obtain values for alkalinity based on the so called “locally interpolated alkalinity regression (LIAR)” method after Carter et al., 2016; 2018.

• Build on surface ocean partial pressure of carbon dioxide (CMEMS product: MULTIOBS_GLO_BIO_CARBON_SURFACE_REP_015_008) obtained from an ensemble of Feed-Forward Neural Networks (Chau et al. 2021) which exploit sampling data gathered in the Surface Ocean CO2 Atlas (SOCAT) (https://www.socat.info/)

• Derive a gridded field of ocean surface pH based on the van Heuven et al., (2011) CO2 system calculations using reconstructed pCO2 (MULTIOBS_GLO_BIO_CARBON_SURFACE_REP_015_008) and alkalinity.

The global mean average of pH at yearly time steps is then calculated from the gridded ocean surface pH field. It is expressed in pH unit on total hydrogen ion scale. In the figure, the amplitude of the uncertainty(1σ) of yearly mean surface sea water pH varies at a range of [0.0021, 0.0024] pH unit (see Quality Information Document for more details). The variation on the trend estimation amounts to 0.0006 pH unit per year.

The indicator is derived from in situ observations of CO2 fugacity (SOCAT data base, www.socat.info, Bakker et al., 2016). These observations are still sparse in space and time. Monitoring pH at higher space and time resolutions, as well as in coastal regions will require a denser network of observations and preferably direct pH measurements.

A scientific publication is in preparation for this indicator.

'''CONTEXT'''

The decrease in surface ocean pH is a direct consequence of the uptake by the ocean of carbon dioxide. It is referred to as ocean acidification. The International Panel on Climate Change (IPCC) Workshop on Impacts of Ocean Acidification on Marine Biology and Ecosystems (2011) defined Ocean Acidification as “a reduction in the pH of the ocean over an extended period, typically decades or longer, which is caused primarily by uptake of carbon dioxide from the atmosphere, but can also be caused by other chemical additions or subtractions from the ocean”. The pH of contemporary surface ocean waters is already 0.1 lower than at pre-industrial times and an additional decrease by 0.33 pH units is projected over the 21st century in response to the high concentration pathway RCP8.5 (Bopp et al., 2013). Ocean acidification will put marine ecosystems at risk (e.g. Orr et al., 2005; Gehlen et al., 2011; Kroeker et al., 2013). The monitoring of surface ocean pH has become a focus of many international scientific initiatives (http://goa-on.org/) and contributes to SDG14 (https://sustainabledevelopment.un.org/sdg14).

'''CMEMS KEY FINDINGS '''

Since the year 1985, global ocean surface pH is decreasing at a rate of -0.00160.0006 per year.

'''DOI (product):'''

https://doi.org/10.48670/moi-00224

 
Citation proposal
Sandrine Mulet (MULTIOBS-CLS-TOULOUSE-FR). Global mean sea water pH. https://services.mspdata.eu:/geonetwork/srv/api/records/1c5fe986-1cd7-4c56-aeff-7bba0b4ff554

Simple

Alternate title
GLOBAL_OMI_HEALTH_carbon_ph_area_averaged
Date ( Creation )
2018-02-12
Edition
3.4
Edition date
2018-02-12
Identifier
1c5fe986-1cd7-4c56-aeff-7bba0b4ff554
Credit
E.U. Copernicus Marine Service Information

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  Originator

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  Resource provider

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Maintenance and update frequency
Annually
Other
P0M0D0H/P0M0D0H
Maintenance note
N/A
GEMET - INSPIRE themes, version 1.0 ( Theme )
  • Oceanographic geographical features
Discipline ( Discipline )
  • in-situ-observation
Climate and Forecast Standard Names ( parameter )
  • sea_water_ph_reported_on_total_scale
Temporal scale ( temporal-scale )
  • multi-year
Area of benefit ( area-of-benefit )
  • marine-safety , weather-climate-and-seasonal-forecasting , marine-resources , coastal-marine-environment
Reference Geographical Areas ( reference-geographical-area )
  • global-ocean
Processing level ( processing-level )
  • N/A
Model assimilation ( Theme )
  • 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 constraints
No limitations on public access
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Date ( Creation )
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Association Type
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Association Type
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Date ( Creation )
2019-05-08
Association Type
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Initiative Type
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Metadata language
eng
Topic category
  • Oceans
Description
bounding box
N
S
E
W


Vertical extent

Minimum value
0
Maximum value
0.0
Vertical CRS
Supplemental Information
display priority: 99999
Unique resource identifier
Codespace
EPSG
Number of dimensions
2
Dimension name
Row
Dimension name
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Cell geometry
Area
Transformation parameter availability
false
Distribution format
  • NetCDF-4 ( )

OnLine resource
global_omi_health_carbon_ph_area_averaged  
Hierarchy level
Series

Conformance result

Date ( Publication )
2010-12-08
Explanation
See the referenced specification
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']")

Metadata

File identifier
1c5fe986-1cd7-4c56-aeff-7bba0b4ff554   XML
Metadata language
English
Character set
UTF8
Hierarchy level
Series
Hierarchy level name
Copernicus Marine Service product specification
Date stamp
2021-12-13T12:54:04
Metadata standard name
ISO 19139, MyOcean profile
Metadata standard version
0.2

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http://marine.copernicus.eu/  
 
 

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