f50a428b-ccb1-413d-9afd-43629d273b76 Copernicus Marine Service product specification CMEMS servicedesk.cmems@mercator-ocean.eu http://marine.copernicus.eu/ 2025-04-22T08:15:13.951612Z ISO 19139, MyOcean profile 0.2 2 4 4 false Equirectangular EPSG North Atlantic Gyre Area Chlorophyll-a time series and trend from Observations Reprocessing OMI_HEALTH_CHL_GLOBAL_OCEANCOLOUR_oligo_nag_area_mean 2019-11-28 3.4 2023-03-30 a78600a4-a280-47b5-8ddd-0dc8b5e9c9d9 '''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 North Atlantic gyre area for the 1997 Sept – 2021 December period was positive, with a 0.14% year-1 increase in area relative to 2000-01-01 values. This trend has decreased compared with the 1997-2019 trend of 0.39%, and is no longer statistically significant (p>0.05). During the 1997 Sept – 2021 December period, the trend in chlorophyll concentration was negative (-0.21% year-1) inside the North Atlantic gyre relative to 2000-01-01 values. This is a slightly lower rate of change compared with the -0.24% trend for the 1997-2020 period but is still statistically significant (p<0.05). '''DOI (product):''' https://doi.org/10.48670/moi-00226 E.U. Copernicus Marine Service Information OC-PML-PLYMOUTH-UK P0M0D0H/P0M0D0H N/A https://documentation.marine.copernicus.eu/IMG/OMI_HEALTH_CHL_GLOBAL_OCEANCOLOUR_oligo_nag_area_mean.png Oceanographic geographical features GEMET - INSPIRE themes, version 1.0 2009-09-22 satellite-observation Discipline 2017-04-25 geonetwork.thesaurus.local.discipline.myocean.discipline area_type_oligotropic_gyre mass_concentration_of_chlorophyll_in_seawater_for_averaged_mean Climate and Forecast Standard Names 2017-04-04 geonetwork.thesaurus.external.parameter.myocean.ocean-variables multi-year Temporal scale 2024-07-26 geonetwork.thesaurus.local.temporal-scale.myocean.temporal-scale marine-resources coastal-marine-environment weather-climate-and-seasonal-forecasting marine-safety Area of benefit 2024-07-26 geonetwork.thesaurus.local.area-of-benefit.myocean.area-of-benefit global-ocean Reference Geographical Areas 2024-07-26 geonetwork.thesaurus.local.reference-geographical-area.myocean.reference-geographical-area Level 4 Processing level 2024-07-26 geonetwork.thesaurus.local.processing-level.myocean.processing-level Not Applicable Model assimilation 2016-02-03 geonetwork.thesaurus.external.theme.myocean.model-assimilation See Copernicus Marine Environment Monitoring Service Data commitments and licence at: http://marine.copernicus.eu/web/27-service-commitments-and-licence.php No limitations on public access Aiken J, Brewin RJW, Dufois F, Polimene L, Hardman-Mountford NJ, Jackson T, Loveday B, Hoya SM, Dall’Olmo G, Stephens J, et al. 2016. A synthesis of the environmental response of the North and South Atlantic sub-tropical gyres during two decades of AMT. Prog Oceanogr. doi:10.1016/j.pocean.2016.08.004. 2019-05-08 McClain CR, Signorini SR, Christian JR 2004. Subtropical gyre variability observed by ocean-color satellites. Deep Sea Res Part II Top Stud Oceanogr. 51:281–301. doi:10.1016/j.dsr2.2003.08.002. 2019-05-08 Polovina JJ, Howell EA, Abecassis M 2008. Ocean’s least productive waters are expanding. Geophys Res Lett. 35:270. doi:10.1029/2007GL031745. 2019-05-08 Sathyendranath S, Pardo S, Brewin RJW. 2018. Oligotrophic gyres. In: Copernicus Marine Service Ocean State Report, Issue 2, Journal of Operational Oceanography, 11:sup1, s13–s16, DOI: 10.1080/1755876X.2018.1489208 2019-05-08 Signorini SR, Franz BA, McClain CR 2015. Chlorophyll variability in the oligotrophic gyres: mechanisms, seasonality and trends. Front Mar Sci. 2. doi:10.3389/fmars.2015.00001. 2019-05-08 696d3889-ac46-438f-a397-dd2227c6396b 3ef35088-7164-452b-a463-2194a17b68bd 06f3ffff-06e0-414b-bbbb-e2d3fbe43508 eng oceans bounding box -85.00 0.00 5.00 45.00 1997-09-04 0 0 display priority: 53800 observation vertical level number: 1 false Grid NetCDF-4 Classic model https://stac.marine.copernicus.eu/metadata/OMI_HEALTH_CHL_GLOBAL_OCEANCOLOUR_oligo_nag_area_mean/omi_health_chl_global_oceancolour_oligo_nag_area_mean_202211/dataset.stac.json WWW:STAC omi_health_chl_global_oceancolour_oligo_nag_area_mean For accessing native data and Analysis-ready Cloud-optimized data services, consult this STAC metadata endpoint COMMISSION REGULATION (EU) No 1089/2010 of 23 November 2010 implementing Directive 2007/2/EC of the European Parliament and of the Council as regards interoperability of spatial data sets and services 2010-12-08 See the referenced specification 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']")