GCRI · Oceans and Coasts
Ocean observation
The ocean is measured by a global system of profiling floats, moored buoys, tide gauges, research and commercial ships, gliders and satellites. These observations underpin forecasts, climate monitoring, fisheries and coastal planning, but coverage is uneven and depends on sustained funding and data sharing. This page sets out how ocean observation is organised, where gaps lie, and what evidence serves those who fund and use it.
Ocean observation on the record.
Ocean observation: how the risk develops.
Marine sensing and data limitations. The dossier below sets out how the risk develops, what is measured, where the data come from, how it is modelled and who decides.
Many platforms, one system
Floats profile temperature and salinity in the upper ocean, moorings watch fixed points, satellites map the surface, and ships measure what others cannot. Together they form the Global Ocean Observing System.
Coverage is uneven
The deep ocean, polar seas, coastal zones and waters of many developing countries are poorly observed. Biogeochemical and biological variables lag physical ones.
Continuity depends on funding
Much observation is funded through research grants. When funding ends, records break, and the value of long series is lost.
Data must flow openly
Observations are useful only when shared quickly in standard formats. Free and open data exchange underpins forecasting and climate assessment.
Ocean state in Pacific Island states.
Marine heat, chlorophyll and sea temperature over Pacific Island states, from NASA GIBS. Each layer carries its own date.
The interactive map needs JavaScript; the layer list and sources are below.
Layers 3
Ocean state, for this page
About this layer
- Evidence
- Observed
- Source
- GHRSST MUR25 (NASA JPL PO.DAAC)
- Provider
- NASA JPL PO.DAAC
- Licence
- NASA open data
- Vintage
- daily; Satellite analysis
- Newest at build
- 2026-10-12
- Resolution
- about 2 km grid
- Uncertainty
- Satellite analysis of how far sea temperature departs from its usual value for the date shown; a marine heat indicator, not a coral bleaching alert.
- Reached through
- gibs.earthdata.nasa.gov, only after you allow the live map
About this layer
- Evidence
- Observed (clouds and sun glint leave gaps)
- Source
- MODIS Aqua ocean colour (NASA OB.DAAC)
- Provider
- NASA OB.DAAC
- Licence
- NASA open data
- Vintage
- daily; Satellite retrieval; clouds and sun glint leave gaps
- Newest at build
- 2026-10-13
- Resolution
- about 1 km grid
- Uncertainty
- Satellite estimate of chlorophyll-a near the sea surface on the day shown, an indicator of plankton and ocean productivity; not a measure of fish stocks or harmful blooms.
- Reached through
- gibs.earthdata.nasa.gov, only after you allow the live map
About this layer
- Evidence
- Observed
- Source
- GHRSST MUR (NASA JPL PO.DAAC)
- Provider
- NASA JPL PO.DAAC
- Licence
- NASA open data
- Vintage
- daily; Satellite analysis
- Newest at build
- 2026-10-12
- Resolution
- about 1 km grid
- Uncertainty
- Gap-filled satellite analysis of sea surface temperature for the date shown; not a reef or species condition report.
- Reached through
- gibs.earthdata.nasa.gov, only after you allow the live map
About this layer
- Evidence
- Observed
- Source
- VIIRS NOAA-20 corrected reflectance (NASA LANCE)
- Provider
- NASA LANCE
- Licence
- NASA open data
- Vintage
- daily; Satellite image
- Newest at build
- 2026-10-14
- Resolution
- about 250 m grid
- Uncertainty
- Satellite image. Satellite or model raster as the provider publishes it. Clouds, swath gaps and retrieval error leave gaps and noise; values are indicators, not measurements at a place.
- Reached through
- gibs.earthdata.nasa.gov, only after you allow the live map
About this layer
- Evidence
- Modelled (latest year GIBS publishes)
- Source
- MODIS Terra and Aqua land cover (MCD12Q1) (NASA LP DAAC)
- Provider
- NASA LP DAAC
- Licence
- NASA open data
- Vintage
- yearly; Satellite classification; latest year GIBS publishes
- Newest at build
- 2024-01-01
- Resolution
- about 500 m grid
- Uncertainty
- Satellite land cover classes for the year shown, including croplands; a classification with known errors, not a farm register.
- Reached through
- gibs.earthdata.nasa.gov, only after you allow the live map
About this layer
- Evidence
- Observed
- Source
- VIIRS Black Marble (VNP46A2) (NASA LAADS DAAC)
- Provider
- NASA LAADS DAAC
- Licence
- NASA open data
- Vintage
- daily; Satellite radiance, corrected for moonlight and atmosphere
- Newest at build
- 2026-10-12
- Resolution
- about 500 m grid
- Uncertainty
- Satellite night-time radiance for the date shown; lights are a proxy for electricity use and outages, not a measurement of supply or access.
- Reached through
- gibs.earthdata.nasa.gov, only after you allow the live map
Keyboard, with the map focused
Hold Ctrl or ⌘ and scroll to zoom
Latest available
NASA GIBS / EOSDIS · ASTER GDEM (METI, NASA) · Blue Marble (NASA) · © OpenStreetMap contributors (ODbL) · Natural Earth
Loading the latest NASA imagery.
Drag to move. Ctrl or ⌘ and scroll, pinch or the buttons to zoom; hover for the values under the pointer; reset returns to the region.
Ocean state, framed on Pacific Island states.Satellite and model products as NASA publishes them, each with its own date. They are indicators, not assessments of any place.
Data: NASA GIBS · ASTER GDEM · Blue Marble · © OpenStreetMap contributors · Natural Earth · NASA EONET · NASA PACE OCI · NASA JPL OPERA DIST-ALERTSources and licences
- We acknowledge the use of imagery provided by services from NASA’s Global Imagery Browse Services (GIBS), part of NASA’s Earth Science Data and Information System (ESDIS). Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
- We acknowledge the use of imagery provided by services from NASA’s Global Imagery Browse Services (GIBS), part of NASA’s Earth Science Data and Information System (ESDIS). Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
- GHRSST Level 4 MUR analyses, NASA Jet Propulsion Laboratory; distributed by the NASA Physical Oceanography DAAC (PO.DAAC); imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
- MODIS Aqua ocean colour, NASA Ocean Biology Processing Group; distributed by the NASA Ocean Biology DAAC (OB.DAAC); imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
- VIIRS near-real-time products (flood, land surface temperature, snow cover, corrected reflectance), NASA LANCE; imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
- MODIS land products (vegetation indices, gross primary production, land cover), NASA LP DAAC and LANCE; imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
- VIIRS Black Marble night-time lights, NASA Goddard Space Flight Center; distributed by the NASA Level-1 and Atmosphere Archive and Distribution System (LAADS DAAC); imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
- ASTER GDEM is a product of METI and NASA (ASTER Global Digital Elevation Model V003, NASA LP DAAC); imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). Cite as: NASA/METI/AIST/Japan Spacesystems and U.S./Japan ASTER Science Team (2019). ASTER Global Digital Elevation Model V003. doi:10.5067/ASTER/ASTGTM.003. NASA open data
- Made with Natural Earth. Free vector and raster map data @ naturalearthdata.com. Public domain
- © OpenStreetMap contributors (ODbL), via NASA GIBS (coastlines, boundaries, roads and place names). Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). ODbL
- Blue Marble, NASA Earth Observatory; imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
- Context on the globe and flat map: coastlines, boundaries, roads and place names from NASA GIBS reference layers (OpenStreetMap data, ODbL, © OpenStreetMap contributors); Blue Marble imagery as an optional base; 3D terrain and the elevation read-out from the ASTER GDEM elevation colour index (5 m to 200 m classes, exaggerated for legibility). Boundaries are drawn as published and imply no position on any territory.
- Live events: NASA Earth Observatory Natural Event Tracker (EONET); events are indicative and keep their original source links.
- Live: NASA EONET Events are indicative, not authority warnings.
- Observed (EO): NASA PACE OCI. We acknowledge the use of imagery provided by services from NASA’s Global Imagery Browse Services (GIBS), part of NASA’s Earth Science Data and Information System (ESDIS).
- Observed (EO): NASA JPL OPERA DIST-ALERT (contains modified Copernicus Sentinel data 2026). We acknowledge the use of imagery provided by services from NASA’s Global Imagery Browse Services (GIBS), part of NASA’s Earth Science Data and Information System (ESDIS).
- NASA GIBS: We acknowledge the use of imagery provided by services from NASA’s Global Imagery Browse Services (GIBS), part of NASA’s Earth Science Data and Information System (ESDIS).
- Weather data by Open-Meteo.com (https://open-meteo.com/), licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/).
- Optional layers (10 sources in the layer list: live, forecast, observed and context) print their provider credit on the map and here when switched on; forecasts are model output and derived indices are estimates.
Layers and dates
- Sea surface temperature anomaly: GHRSST MUR25, NASA JPL PO.DAAC · 12 Oct 2026
- Ocean chlorophyll-a concentration: MODIS Aqua ocean colour, NASA OB.DAAC · 12 Oct 2026
- Sea surface temperature: GHRSST MUR, NASA JPL PO.DAAC · 12 Oct 2026
- True colour: VIIRS NOAA-20 corrected reflectance, NASA LANCE · 13 Oct 2026
- Land cover type (IGBP), yearly: MODIS Terra and Aqua land cover (MCD12Q1), NASA LP DAAC · 2024
- Night-time lights, daily: VIIRS Black Marble (VNP46A2), NASA LAADS DAAC · 12 Oct 2026
Ocean observations feed forecasts used in every domain.
- WaterCouplingOcean temperatures drive monsoons and droughts on land.What to watchSea surface temperature anomalies
- FoodCouplingSeasonal forecasts rely on ocean state.What to watchForecast skill linked to ocean data
- BiodiversityCouplingMarine heatwaves are detected from observations.What to watchHeatwave detection
Observation evidence is designed for the Observatory Signal series. GOOS defines the Essential Ocean Variables, Argo floats profile the upper ocean, and GEBCO compiles bathymetry; datasets would carry NS-3b metadata under the proposed Nexus Standards.
- Coastal observations from local networks.
- Data rescue of historical records.
Fisheries and marine watch.
The screen a team would use to follow this subject: its measures, states and decisions. Names are examples and values are illustrative.
Fisheries and marine watch
Ocean observation · Fishing grounds 3 · Season 1
- Biomass vs reference point0.8ratioWatch
- Marine heatwave days14this yearAlert
- Fleet effort95index
Sea surface temperature anomaly
Stock status
| Small pelagic | 0.7 | 1.5 | Sustainable |
| Reef fish | 0.9 | 1.3 | Overfished |
| Tuna-like | 1.0 | 0.9 | Sustainable |
What is measured, and how well.
Each indicator carries its unit, its cadence, the kind of source behind it and the evidence label a value would carry. No values are shown: a programme supplies them under its own authority.
| Indicator | Unit | Cadence | Source type | Label |
|---|---|---|---|---|
| Operational Argo floats | count | monthly | Argo programme status | OBSERVED |
| Essential ocean variables with sustained observation | count by variable readiness level | per assessment | GOOS assessments | Published statistics |
| Tide gauges reporting in near real time | count | annual | GLOSS and national networks | OBSERVED |
| Coastal waters observed by in situ systems | percent of national coastline with monitoring | per assessment | National observing system records | REPORTED |
| Data latency | hours from measurement to availability | per platform | Data system records | OBSERVED |
| Ocean science capacity | researchers and research vessels per country | per assessment | IOC Global Ocean Science Report | REPORTED |
Model ocean observation as a system. Run the cascade.
Assembled from the Nexus Standards area profile Oceans and coasts risk standards: the hazards it names, the systems and sectors that carry the loss, the controls that dampen it and the data that observe it. Choose the components, pick an initiating hazard and step through the cascade. The Map view places the run on an example geography with open data. Every coupling weight is a stated assumption you can change. A teaching model, not a forecast, an assessment or a certification. To model a place of your own choosing, open the full System Builder.
Hazards
- Sea-level rise
- Storm surge
- Coastal erosion
- Heatwave
- Ocean acidification
- Harmful algal bloom
- Extreme fire weather (set off downstream)
- Wildfire (set off downstream)
- Heat-driven grid stress (set off downstream)
- Agricultural drought (set off downstream)
- Flash drought (set off downstream)
- Snow drought (set off downstream)
- Ground-level ozone episode (set off downstream)
- Meteorological drought (set off downstream)
- River flood (set off downstream)
- Coastal flood (set off downstream)
- Estuary flood (set off downstream)
- Mass displacement (set off downstream)
Systems and couplings
- Oceans and coasts risk standards
- Supply chain and trade risk Cascade
- Food and agriculture risk standards Cascade
- Climate risk standards Common driver and feedback
- Cities and urban systems risk standards Exposure
Controls
NS-0Constitution and principlesNS-1The UNI and the artefact catalogue (grammar v0.2: domain, sector, region and environment segments)NS-3Risk record UNIs (grammar, legacy crosswalk, allocation authority)NS-3bDataset and product metadata profile (STAC, DCAT, PROV-O)NS-5Figure, map and visualisation standard (with the UI/UX kit)NS-9Contextual UNIs (deployments, instances, programme instances)NS-11Verification and monitoring (evidence, attestations, zero-trust conformance observation)NRS-X3Oceans and coasts riskNRS-H11Hazard family: Coastal and sea-level hazards (NHS-1 water.coastal)NRS-H79Hazard family: Mental health crises (NHS-1 health.mental)NRS-H12Hazard family: Ocean-state extremes (NHS-1 water.ocean-state)NRS-H67Hazard family: Ocean circulation and marine tipping (NHS-1 planet.ocean-tipping)NRS-K18Domain pack profile: Oceans coastal (DOMAIN-018)
Observation
- Copernicus Marine Service ocean products (listed for reference)
- Coral Reef Watch daily 5 km heat stress products (listed for reference)
- PSMSL tide gauge mean sea level records (listed for reference)
- GEBCO global bathymetric grid (listed for reference)
- Argo float profiles (listed for reference)
- Average marine acidity (pH) measured at agreed suite of representative sampling stations
- Index of coastal eutrophication and floating plastic debris density
- Direct economic loss attributed to disasters in relation to GDP, including damage to critical infrastructure
Example geography
- Pacific Island states: 150 hexagonal cells
- Night lights tonight, outages (VIIRS Day/Night Band), NASA GIBS
- Surface water through cloud, 30 m (OPERA DSWx-S1 radar), NASA GIBS
- Rain rate, last half hour (IMERG), NASA GIBS
- Surface air temperature, daytime (AIRS), NASA GIBS
Where the evidence comes from.
Named public datasets and institutional records, each with its licence class. Sources by agreement are used only under their terms and never republished.
| Source | What it gives | Licence class |
|---|---|---|
| Argo programme data | Global temperature, salinity and biogeochemical profiles | Free and open, Argo data policy |
| OceanOPS (WMO and IOC) | Status of ocean observing platforms worldwide | Public, OceanOPS terms |
| IOC Global Ocean Science Report | National ocean science capacity and investment | Public, UNESCO terms (CC BY-SA 3.0 IGO for many) |
| GLOSS tide gauge network | Core network of tide gauges for sea level | Free, terms per data centre |
| World Ocean Database (NOAA NCEI) | Quality-controlled archive of ocean profile data | Public domain, US government data |
How ocean observation is modelled, measured and tested.
The model, its assumptions, its data and its uncertainty, in the form a scientist or engineer would check. Structures follow published methods. The values drawn are illustrative, not findings.
Earth observation chain
How a satellite or sensor record becomes evidence on ocean observation, and where each step adds uncertainty.
- 01 · Acquireorbit, sensor and revisitUncertainty: gaps from cloud and orbit
- 02 · Calibrateradiometric and geometricUncertainty: sensor drift
- 03 · Correctatmosphere and terrainUncertainty: aerosol and slope assumptions
- 04 · Retrieve or classifythe variable or the classUncertainty: model and training error
- 05 · Validateagainst ground truthUncertainty: sample design and size
- 06 · Publishwith error bars and lineageUncertainty: stated, never hidden
Who decides, and what the evidence serves.
Oceans and Coasts prepares evidence. The decisions below are taken by the authorities named, under their own rules, and never by the platform.
| Who decides | The question | Evidence this page serves |
|---|---|---|
| National oceanographic and meteorological agencies | Which observations to sustain or add | Gap maps; readiness reviews |
| Research funders | How to fund long-term observation beyond project cycles | Continuity and gap evidence |
| Regional organisations | How to share observing capacity across countries | Capacity and data flow evidence |
Outputs this topic produces
- Observation gap maps for national waters and regions
- Readiness reviews of essential ocean variables
- Data flow reviews from platform to user
- Evidence notes for ocean observing investment
The questions experts ask.
- What is measured, where, how often and with what accuracy?
- Where are the gaps, by region, depth and variable, and how do they bias analysis?
- How are records from different instruments joined into consistent long series?
- Who owns and maintains observing systems, and how secure is their funding?
- How quickly does data reach those who need it during an event?
The observing system and its gaps.
The global ocean observing system combines satellite missions for sea-surface height, temperature, colour, winds and sea ice with in-situ networks: autonomous profiling floats, moored buoys, drifters, tide gauges, research and volunteer ships, and gliders. Coastal observing adds high-frequency radar, nearshore buoys and water-quality sensors. Together they feed forecasts, climate records and hazard warnings.
Coverage is uneven. The deep ocean, polar seas, coastal zones of many lower-income countries and biological and biogeochemical variables are under-observed. Satellites see the surface, not the interior, and struggle close to the coast. Long records exist at few locations, which limits trend and extreme-value analysis. Many networks depend on research funding renewed over short cycles, so continuity is itself a risk.
Observation also has a human dimension. Fishers, coastal communities and citizen scientists record changes in species, water quality and shoreline position that formal networks miss, and such records, gathered with consent and quality control, can fill gaps at the scales where decisions are made.
Methods and their limits.
Remote sensing
Altimetry, radiometry and ocean colour give global coverage of the surface, with reduced accuracy near coasts and under cloud.
Floats, buoys and gauges
Direct measurements of temperature, salinity, currents and sea level at points and profiles.
Reanalysis and assimilation
Models combine observations into gridded fields; where data are sparse, results lean on the model.
Limits: changes of instrument and method can create artificial shifts in records, and gridded products may look complete where few observations exist. Analysis should state which observations underlie a result.
How it is studied, and what the methods cannot say.
- 01Ocean and coastal scienceRegional sea-level budgets · Marine heatwave analysis · Wave climate assessmentApplied here
- 02Earth observation and remote sensingOcean colour and blooms · Shoreline change mapping · Coastal habitat mappingApplied here
- 03Geospatial information systemsCoastal exposure mapping · Marine spatial planning layers · Fishing effort mappingApplied here
- 04Water and environmental engineeringCoastal defence options · Coastal wastewater planning · Adaptation pathwaysApplied here
Where this page’s references lead.
The bodies and documents this page is read against. Status and editions change; each link goes to the issuing body.
Questions and answers.
What is Argo?
What are essential ocean variables?
Why does open ocean data matter?
Does the platform operate sensors?
Why are coastal zones poorly observed by satellites?
How are gaps represented in results?
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