fd526e1b-b581-40b4-b1a8-45278a9a4dd2 Copernicus Marine Service product specification CMEMS servicedesk.cmems@mercator-ocean.eu http://marine.copernicus.eu/ 2025-09-29T14:30:00.783308Z ISO 19139, MyOcean profile 0.2 2 false EPSG [ARCHIVE] Global Ocean, extreme and mean significant wave height trends from satellite observations - seasonal trends OMI_EXTREME_SEASTATE_GLOBAL_swh_mean_and_P95_obs 2024-11-26 3.4 2024-11-26 a78600a4-a280-47b5-8ddd-0dc8b5e9c9d9 '''This product has been archived''' '''DEFINITION''' Significant wave height (SWH), expressed in metres, is the average height of the highest one-third of waves. This OMI provides time series of seasonal mean and extreme SWH values in three oceanic regions as well as their trends from 2002 to 2020, computed from the reprocessed global L4 SWH product (WAVE_GLO_PHY_SWH_L4_MY_014_007). The extreme SWH is defined as the 95th percentile of the daily maximum of SWH over the chosen period and region. The 95th percentile represents the value below which 95% of the data points fall, indicating higher wave heights than usual. The mean and the 95th percentile of SWH are calculated for two seasons of the year to take into account the seasonal variability of waves (January, February, and March, and July, August, and September) and are in m while the trends are in cm/yr. '''CONTEXT''' Grasping the nature of global ocean surface waves, their variability, and their long-term interannual shifts is essential for climate research and diverse oceanic and coastal applications. The sixth IPCC Assessment Report underscores the significant role waves play in extreme sea level events (Mentaschi et al., 2017), flooding (Storlazzi et al., 2018), and coastal erosion (Barnard et al., 2017). Additionally, waves impact ocean circulation and mediate interactions between air and sea (Donelan et al., 1997) as well as sea-ice interactions (Thomas et al., 2019). Studying these long-term and interannual changes demands precise time series data spanning several decades. Until now, such records have been available only from global model reanalyses or localised in situ observations. While buoy data are valuable, they offer limited local insights and are especially scarce in the southern hemisphere. In contrast, altimeters deliver global, high-quality measurements of significant wave heights (SWH) (Gommenginger et al., 2002). The growing satellite record of SWH now facilitates more extensive global and long-term analyses. By using SWH data from a multi-mission altimetric product from 2002 to 2020, we can calculate global mean SWH and extreme SWH and evaluate their trends. '''KEY FINDINGS''' Over the period from 2002 to 2020, positive trends in both Significant Wave Height (SWH) and extreme SWH are mostly found in the southern hemisphere. The 95th percentile of wave heights (q95), increases more rapidly than the average values, indicating that extreme waves are growing faster than the average wave height. In the North Atlantic, SWH has increased in summertime (July August September) and decreased during the wintertime: the trend for the 95th percentile SWH is decreasing by 2.1 ± 3.3 cm/year, while the mean SWH shows a decreasing trend of 2.2 ± 1.76 cm/year. In the south of Australia, in boreal winter, the 95th percentile SWH is increasing at a rate of 2.6 ± 1.5 cm/year (a), with the mean SWH increasing by 0.7 ± 0.64 cm/year (b). Finally, in the Antarctic Circumpolar Current, also in boreal winter, the 95th percentile SWH trend is 3.2 ± 2.15 cm/year (a) and the mean SWH trend is 1.4 ± 0.82 cm/year (b). This variation highlights that waves evolve differently across different basins and seasons, illustrating the complex and region-specific nature of wave height trends. A full discussion regarding this OMI can be found in A. Laloue et al. (2024). '''DOI (product):''' https://doi.org/10.48670/mds-00352 E.U. Copernicus Marine Service Information WAVE-CLS-TOULOUSE-FR P0M0D0H/P0M0D0H N/A https://documentation.marine.copernicus.eu/IMG/OMI_EXTREME_SEASTATE_GLOBAL_swh_mean_and_P95_obs.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 sea_surface_wave_significant_height_seasonal_mean sea_surface_wave_significant_height_seasonal_95percentile sea_surface_wave_significant_height_mean_trend sea_surface_wave_significant_height_95percentile_trend sea_surface_significant_height_seasonal_number_of_observations sea_surface_significant_height sea_surface_significant_height_trend_uncertainty_95percentile sea_surface_significant_height_trend_uncertainty_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 weather-climate-and-seasonal-forecasting marine-safety marine-resources coastal-marine-environment Area of benefit 2025-07-29 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 N/A 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 Barnard, P. L., Hoover, D., Hubbard, D. M., Snyder, A., Ludka, B. C., Allan, J., Kaminsky, G. M., Ruggiero, P., Gallien, T. W., Gabel, L., McCandless, D., Weiner, H. M., Cohn, N., Anderson, D. L., and Serafin, K. A.: Extreme oceanographic forcing and coastal response due to the 2015–2016 El Niño, Nature Communications, 8, https://doi.org/10.1038/ncomms14365, 2017. 2019-05-08 Donelan, M. A., Drennan, W. M., and Katsaros, K. B.: The air–sea momentum flux in conditions of wind sea and swell, Journal of Physical Oceanography, 27, 2087–2099, https://doi.org/10.1175/1520-0485(1997)0272.0.co;2, 1997. 2019-05-08 Mentaschi, L., Vousdoukas, M. I., Voukouvalas, E., Dosio, A., and Feyen, L.: Global changes of extreme coastal wave energy fluxes triggered by intensified teleconnection patterns, Geophysical Research Letters, 44, 2416–2426, https://doi.org/10.1002/2016gl072488, 2017 2019-05-08 Thomas, S., Babanin, A. V., Walsh, K. J. E., Stoney, L., and Heil, P.: Effect of wave-induced mixing on Antarctic sea ice in a high-resolution ocean model, Ocean Dynamics, 69, 737–746, https://doi.org/10.1007/s10236-019-01268-0, 2019. 2019-05-08 Gommenginger, C. P., Srokosz, M. A., Challenor, P. G., and Cotton, P. D.: Development and validation of altimeter wind speed algorithms using an extended collocated Buoy/Topex dataset, IEEE Transactions on Geoscience and Remote Sensing, 40, 251–260, https://doi.org/10.1109/36.992782, 2002. 2019-05-08 Storlazzi, C. D., Gingerich, S. B., van Dongeren, A., Cheriton, O. M., Swarzenski, P. W., Quataert, E., Voss, C. I., Field, D. W., Annamalai, H., Piniak, G. A., and McCall, R.: Most atolls will be uninhabitable by the mid-21st century because of sea level rise exacerbating wave-driven flooding, Science Advances, 4, https://doi.org/10.1126/sciadv.aap9741, 2018. 2019-05-08 Husson, R., Charles, E.: EU Copernicus Marine Service Product User Manual for the Global Ocean L 4 Significant Wave Height From Reprocessed Satellite Measurements Product, WAVE_GLO_PHY_SWH_L4_MY_014_007, Issue 2.0, Mercator Ocean International, https://documentation.marine.copernicus.eu/PUM/CMEMS-WAV-PUM-014-005-006-007.pdf, last access: 21 July 2023, 2021 Laloue, A., Ghantous, M., Faugère, Y., Dalphinet. A., Aouf, L.: Statistical analysis of global ocean significant wave heights from satellite altimetry over the past two decades. OSR-8 (under review) 2019-05-08 3880057d-d1ad-4fd9-b93a-e0cf3fbb7084 31a1122d-e74c-420a-a586-ff33cd1115ee 94dfa859-f336-463d-a175-1679b80961c0 eng oceans bounding box -52.00 155.00 -66.00 43.00 seasonal-means 2001-11-15 display priority: 53800 observation vertical level number: 1 false timeseries NetCDF-4 http://stac.marine.copernicus.eu/metadata/OMI_EXTREME_SEASTATE_GLOBAL_swh_mean_and_P95_obs/omi_extreme_seastate_global_swh_mean_and_p95_obs_202411/dataset.stac.json WWW:STAC omi_extreme_seastate_global_swh_mean_and_p95_obs 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']")