A collection of original data animations exploring the ocean through satellite and reanalysis data, mostly rendered on the Spilhaus projection. Free to use for teaching and outreach (CC-BY 4.0, please credit Oceanofísica/ULPGC).
Ocean color
Sea surface color (1997-2025)
This is ocean surface chlorophyll from September 1997 to December 2025, seen from space. Chlorophyll is the pigment of phytoplankton: microscopic algae responsible for roughly half of the photosynthesis on the planet and the base of almost all marine life.
The colour scale is logarithmic: each step means ten times more chlorophyll. Between the centre of a gyre and a coastal upwelling there is more than a thousandfold difference.
The map uses the Spilhaus projection, which shows the world ocean as a single continuous body of water, with Antarctica at the centre.
Data: ESA Climate Change Initiative, Ocean Colour v6.0
Mean sea surface color (1997-2025, 3D globe)
This globe shows the mean surface chlorophyll-a from 1997 to 2025, measured by satellites. Chlorophyll tracks phytoplankton, the microscopic algae that carry out roughly half of the photosynthesis on Earth.
The surface is deformed to make the pattern easier to read: waters richer than the global average rise outward, poorer waters sink inward. It is a visual device, not real topography.
Colours are on a logarithmic scale, from 0.01 to 10 mg per cubic metre: each step is ten times more chlorophyll.
This is the companion of our monthly Spilhaus animation of chlorophyll: that one shows how the ocean breathes season by season, this one shows its long-term average.
Data: ESA Climate Change Initiative, Ocean Colour v6.0
Sea Level
Sea level anomaly (1993-2025)
Since 1993, satellite altimetry has measured the height of the ocean surface with millimeter precision. This animation shows the monthly sea level anomaly (Copernicus/CMEMS, vDT2024) from 1993 to 2025, projected onto the Spilhaus projection, which shows the world ocean as a single connected body of water instead of cutting it into pieces at the map edges.
Three things to look for. First, the long-term shift: blues dominate in the early 1990s and gradually give way to reds by the 2020s, the visible signature of global sea level rise. Second, the swirls: those aren't noise, they're mesoscale eddies, rotating bodies of water tens to hundreds of km across that show up as local sea level bumps and dips. Most drift westward, following the same physics that steers hurricanes, except in the Antarctic Circumpolar Current, the one place on Earth where the dominant flow overwhelms that tendency and eddies get swept eastward instead. Third, the polar regions flicker: that's not missing data by accident, altimeters can't see the sea surface through sea ice, so those patches blink in and out with the seasonal advance and retreat of Arctic and Antarctic ice each year.
Data: Copernicus Marine Service (CMEMS), satellite altimetry, DUACS vDT2024
Sea level trend (1993-2025, 3D globe)
The pattern is far from uniform. While the global average sits around 3-4 mm/year, some regions, especially the western Pacific, are rising two to three times faster, driven by ocean dynamics and heat redistribution, not just total volume added. A few pockets show little change or even a slight decline over the same 33 years. Global averages hide this kind of regional inequality, and for coastal communities, the regional number is the one that actually matters.
Data: Copernicus Marine Service (CMEMS), satellite altimetry, DUACS vDT2024
Sea Surface Salinity
Monthly sea surface salinity (1993-2025)
Since 1993, oceanographers have tracked sea surface salinity from space and ships alike. This animation shows the monthly global distribution (CMEMS multi-observation product) on the Spilhaus projection, in PSU (practical salinity units), the actual field, not an anomaly, because the structure itself is the story here.
The pattern follows the water cycle almost like a diagram. Salinity peaks in the subtropical gyres of the Atlantic and South Pacific, belts where evaporation far outpaces rainfall, concentrating salt at the surface. It drops toward the poles, diluted by ice melt, river runoff, and net precipitation. And it spikes hardest of all in semi-enclosed seas with limited freshwater input and heavy evaporation, the Mediterranean, the Red Sea, and the Persian Gulf stand out as the saltiest patches on the entire map.
Data: CMEMS multi-observation sea surface salinity
Mean sea surface salinity (3D globe)
This globe shows the mean surface chlorophyll-a from 1997 to 2025, measured by satellites. Chlorophyll tracks phytoplankton, the microscopic algae that carry out roughly half of the photosynthesis on Earth.
The surface is deformed to make the pattern easier to read: waters richer than the global average rise outward, poorer waters sink inward. It is a visual device, not real topography.
Data: CMEMS multi-observation sea surface salinity
Ocean Dynamics
Ocean surface velocity (2025)
Every trace is a virtual particle carried by the mean surface current of 2025. The colour and the length of the trail both show speed: long and red means fast, short and blue means slow.
The equatorial current system runs as a set of narrow, almost perfectly straight ribbons. Nowhere else does water move so fast in such an orderly way.
Data: CMEMS MULTIOBS_GLO_PHY_MYNRT_015_003, total surface currents (geostrophic + Ekman)
Mean sea surface kinetic energy (3D globe)
This globe shows the mean kinetic energy of the ocean surface in 2025: how much energy the average current carries at each point. It is the same field as our particle animation, seen as a landscape instead of as flow. Where the water moves fast, the surface bulges outward; where it barely moves, it stays flat.
Data: CMEMS MULTIOBS_GLO_PHY_MYNRT_015_003, total surface currents (geostrophic + Ekman)
Long-lives eddies in the global ocean (2020-2023)
Every dot is a mesoscale eddy: a rotating body of water tens to hundreds of kilometres across, tracked by satellite altimetry from the dip or bulge it makes in the sea surface. Only eddies that survived at least 90 days are shown, and even so there are more than two thousand alive on any given day.
Orange eddies rotate anticyclonically, blue ones cyclonically. The distinction is not cosmetic. Anticyclones trap warm water and depress the thermocline; cyclones lift cold, nutrient-rich water towards the surface and can turn a patch of open ocean into a feeding ground.
Data: META 4.0 mesoscale eddy atlas (AVISO/CLS/CNES), DUACS altimetry
Eddy kinetic energy (1993-2023)
This globe maps the kinetic energy carried by ocean eddies: not the average current, but the swirls that form around it. Every mesoscale eddy detected by satellite altimetry between 1993 and 2023 contributes, and where that energy is high the surface bulges outward.
🔥 The western boundaries. The Gulf Stream, the Kuroshio, the Brazil-Malvinas confluence and above all the Agulhas, south of Africa, burn brightest. These currents are unstable: they meander, pinch off rings, and shed them into the open ocean. The Agulhas leaks rings into the Atlantic that survive for years and carry Indian Ocean water across an entire basin.
Data: META 4.0 mesoscale eddy atlas (AVISO/CLS/CNES), DUACS altimetry
Air-Sea Heat Flux
Monthly net heat flux (1979-2025)
Ocean and atmosphere trade heat constantly, and this animation shows just how much that exchange follows the sun. It's the monthly net heat flux at the ocean surface (ORAS5 reanalysis, 1979-2025), in W/m². Red means the ocean is gaining heat from the atmosphere; blue means it's giving heat back.
Watch the whole map breathe with the seasons. When it's winter in one hemisphere, that ocean is releasing heat (blue), while the other hemisphere, deep in its own summer, is absorbing it (red). Six months later, it flips entirely. A handful of regions never join that back-and-forth: the deep tropics and warm equatorial currents stay red almost year-round, they're net heat absorbers regardless of season, which is exactly why they're the reservoirs that fuel storms and drive circulation in the first place.
Data: ORAS5 (ECMWF ocean reanalysis)
Mean net heat flux (3D globe)
The ocean and atmosphere are constantly trading heat, and that exchange isn't random, it's structured by currents, wind patterns, and geography. This animation shows the 1979-2025 mean net heat flux at the ocean surface (ORAS5 reanalysis), in W/m². Red means the ocean is gaining heat from the atmosphere; blue means it's losing heat to it. Land is shown in flat gray.
For this globe, the deformation direction is reversed from the earlier ones in this series: the surface sinks where the ocean absorbs heat, and rises where it releases it, gaining pictured as an inward pull, releasing as an outward push. As always, this is a stylistic choice, not a physical measurement.
The clearest features are the western boundary currents: the Gulf Stream and the Kuroshio stand out as sharp blue ridges, the ocean's biggest engines for dumping heat back into the atmosphere, warm water pulled from the tropics and cooled rapidly as it meets colder air at mid-latitudes. By contrast, most of the tropical ocean is a broad red band, patiently absorbing solar heat, which currents like these then export toward the poles.
Data: ORAS5 (ECMWF ocean reanalysis)
Sea Ice
Sea ice concentration trend (1979-2025)
Since 1979, ERA5 reanalysis has tracked sea ice cover across both poles, one of the most visible fingerprints of a changing climate. This animation shows the linear trend in annual mean sea ice concentration (%/decade). Land is grey; the vast majority of the ocean, which has never had sea ice and never will, is left pale and blank on purpose. That's not missing data, it's a genuine trend of zero.
Sea ice can only exist in a narrow band around each pole, so almost the entire signal here is compressed into a thin ring hugging the current ice edge, the marginal ice zone, where retreat (or, in a few places, expansion) is actively happening.
In the Arctic, the decline is close to uniform across basins, and the Barents Sea stands out as the single fastest ice-losing region on the planet, part of what's known as the "Atlantification" of that Arctic gateway. Antarctica tells a messier story: for decades, the Ross Sea saw ice slightly expand while the Bellingshausen and Amundsen Seas lost it, a striking regional dipole, before an abrupt, still not fully understood collapse hit nearly the whole continent after 2016. The Weddell Sea sits right at the boundary of these competing signals.
Data: ERA5 (Copernicus Climate Change Service)
Tidal dynamics
M2, the lunar semidiurnal constituent
At any one place the tide rises and falls twice a day. Seen globally, it does something else: it rotates.
This is M2, the lunar semidiurnal constituent, the largest contributor to the tide almost everywhere. One cycle takes 12 h 25 min, which is why high tide arrives about fifty minutes later each day. On a Spilhaus projection, where the ocean appears as the single connected body it is, the structure becomes readable.
⚪ The circles are amphidromic points. At each one the M2 range is essentially zero, and the wave turns around them like water around a drain. The entire global tide is organised around them.
Data: FES2022 (AVISO/CNES/LEGOS)
M2, the lunar semidiurnal constituent: its range (globe 3D)
This globe shows the tidal range of M2, the lunar semidiurnal constituent and the largest contributor to the tide almost everywhere. Not the tide at any particular moment, but how far the sea can move at each point: the difference between high and low water. Where the range is large the surface bulges outward; where the sea barely moves, it stays flat.
🕳 The holes. Scattered across every basin there are points where the range falls to almost nothing. These are amphidromic points, and they are the most counterintuitive feature of the global tide. At these points the M2 tide vanishes, while a few hundred kilometres away the same wave lifts the sea by a metre or more.
Data: FES2022 (AVISO/CNES/LEGOS)
Data Stories
150 years of ocean exploration (1870-2024)
Every station in the World Ocean Database that sampled to at least 100 m depth, flashing at its exact place and time. From HMS Challenger through isolated national expeditions, to the transoceanic collaboration of the postwar decades, to Argo's drifting floats.
It starts with HMS Challenger (1872-76), widely considered the voyage that founded oceanography as a scientific discipline. For decades after, exploration stayed fragmented: individual nations running their own campaigns, mapping the waters off their own coasts, largely working in isolation from one another.
Watch what happens from the 1940s onward. The pattern shifts from scattered dots to long, arrow-straight lines, the signature of transoceanic research cruises, genuine international collaboration replacing isolated national effort. It starts concentrated in the North Atlantic and North Pacific before gradually reaching the rest of the global ocean.
Data: World Ocean Database (NOAA NCEI)
Evolution of CO2 emissions by sector (1990-2023)
Since the 1980s, growing concern over greenhouse gases pushed scientists to start breaking down exactly which human activities were driving emissions, sector by sector: Energy, Agriculture, Industrial Processes, Waste, Land Use Change and Forestry, and international Bunker Fuels (aviation and shipping).
This animation traces how each sector has evolved from 1990 to 2023, the most recent year with available data. One striking result: emissions from the Energy sector alone in 2023 exceed the combined emissions of every sector put together in 1990.
Data: Climate Watch (World Resources Institute)