South Pacific Gyre Area Chlorophyll-a time series and trend from Observations Reprocessing
'''DEFINITION'''
Oligotrophic subtropical gyres are regions of the ocean with low levels of nutrients required for phytoplankton growth and low levels of surface chlorophyll-a whose concentration can be quantified through satellite observations. The gyre boundary has been defined using a threshold value of 0.15 mg m-3 chlorophyll for the Atlantic gyres (Aiken et al. 2016), and 0.07 mg m-3 for the Pacific gyres (Polovina et al. 2008). The area inside the gyres for each month is computed using monthly chlorophyll data from which the monthly climatology is subtracted to compute anomalies. A gap filling algorithm has been utilized to account for missing data. Trends in the area anomaly are then calculated for the entire study period (September 1997 to December 2021).
'''CONTEXT'''
Oligotrophic gyres of the oceans have been referred to as ocean deserts (Polovina et al. 2008). They are vast, covering approximately 50% of the Earth’s surface (Aiken et al. 2016). Despite low productivity, these regions contribute significantly to global productivity due to their immense size (McClain et al. 2004). Even modest changes in their size can have large impacts on a variety of global biogeochemical cycles and on trends in chlorophyll (Signorini et al 2015). Based on satellite data, Polovina et al. (2008) showed that the areas of subtropical gyres were expanding. The Ocean State Report (Sathyendranath et al. 2018) showed that the trends had reversed in the Pacific for the time segment from January 2007 to December 2016.
'''CMEMS KEY FINDINGS'''
The trend in the South Pacific gyre area for the 1997 Sept – 2021 December period was positive, with a 0.04% increase in area relative to 2000-01-01 values. Note that this trend is lower than the 0.16% change for the 1997-2020 period, with the sign of the trend remaining unchanged and is not statistically significant (p<0.05). An underlying low frequency signal is observed with a period of approximately a decade.
During the 1997 Sept – 2021 December period, the trend in chlorophyll concentration was positive (0.66% year-1) in the South Pacific gyre relative to 2000-01-01 values. This rate has increased compared to the rate of 0.45% year-1 for the 1997-2020 period and remains statistically significant (p<0.05). In the last two years of the timeseries, an increase in the variation from the mean is observed.
For 2016, the Ocean State Report (Sathyendranath et al. 2018) reported a large increase in gyre area in the Pacific Ocean (both North and South Pacific gyres), probably linked with the 2016 ENSO event which saw large decreases in chlorophyll in the Pacific Ocean.
'''DOI (product):'''
Simple
- Alternate title
-
OMI_HEALTH_CHL_GLOBAL_OCEANCOLOUR_oligo_spg_area_mean
- Date (Creation)
- 2019-11-28
- Edition
-
3.4
- Edition date
- 2023-03-30
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- a78600a4-a280-47b5-8ddd-0dc8b5e9c9d9
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E.U. Copernicus Marine Service Information
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- Annually
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P0M0D0H/P0M0D0H
- Maintenance note
-
N/A
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GEMET - INSPIRE themes, version 1.0
- 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
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No limitations on public access
- Date (Creation)
- 2019-05-08
- Association Type
- Cross reference
- Initiative Type
- reference
- Date (Creation)
- 2019-05-08
- Association Type
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- Initiative Type
- reference
- Date (Creation)
- 2019-05-08
- Association Type
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- Initiative Type
- reference
- Date (Creation)
- 2019-05-08
- Association Type
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- Date (Creation)
- 2019-05-08
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- document
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- document
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- 9554633e-1238-4d31-b719-75dfbd142a6d
- Association Type
- Cross reference
- Initiative Type
- document
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eng
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- Oceans
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bounding box
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- 1997-09-04
Vertical extent
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display priority: 53800
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NetCDF-4
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Classic model
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NetCDF-4
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Classic model
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Distributor
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omi_health_chl_global_oceancolour_oligo_spg_area_mean
(
WWW:STAC
)
For accessing native data and Analysis-ready Cloud-optimized data services, consult this STAC metadata endpoint
- 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']")
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Copernicus Marine Service product specification
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ISO 19139, MyOcean profile
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0.2