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NASA Made Its Sea Level Changes Data Publicly Available

Catwell

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NASA’s reference grid of sea surface height anomalies. (Image Credit: NASA)

For over three decades, NASA has been using Sea Surface Height (SSH) products derived from satellite altimetry (TOPEX/Poseidon, Jason series, and Sentintel-6) to track weekly sea level changes. Recently, the space agency made that data publicly available. It reveals abrupt, short-term rises and drops in water levels that intensify coastal flooding before annual trends reflect any significant shift. The team at NASA’s JPL calibrated and cross-checked satellites, ensuring consistent weekly measurements. Making the data publicly accessible eliminates lag between research labs and public users who rely on timely data to monitor quickly evolving coastal risks.

These satellites orbit at an altitude of 830 miles, beaming microwave pulses that deflect off the ocean surface. The return time (multiplied by light speed) provides the range to the sea, precise to 3-5 cm after corrections for atmosphere and tides. High-accuracy orbital solutions from GPS, DORIS, and satellite laser ranging track each satellite position to ~1 cm. This allows scientists to calculate sea surface height relative to Earth’s center. Each one-second snapshot covers a 3–6-mile patch, smoothing waves and preserving large-scale patterns.

Afterward, scientists use computers to turn the satellite tracks into NASA-SSH grids on a fixed layout. They merge 10-day observations per map to capture a full repeat cycle. Data is then placed on a 0.5-degree grid and smoothed across nearby points spanning 62 miles to reduce noise. Weekly grids aggregate those spot measurements, which cover 90% of oceans every ten days, into global and regional grids through the NASA Sea Level Change Portal.

However, weekly sea level maps are limited as space-based sensors can’t track all the coastlines in fine detail. Gaps still remain near the poles. And gridded maps capture features at approximately 200-mile resolution. Processing has a two-week delay, and weekly files overlap with the next. This means users monitoring storms must remember that the maps show general trends rather than exact water levels.  

To prevent waters from overlapping each other, the ocean is separated into basins, and each grid point is flagged by region. If water truly connects, the neighboring basins share data. Meanwhile, land barriers block mixing. Using this method preserves coastal details.

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Graph showing sea level rises since 1993. (Image Credit: NASA/JPL-Caltech)

Maps show sea surface height anomalies capturing currents, heat expansion, and events like El Niño. Satellites monitor those changes within days, providing scientists and agencies with insight into regional surges.  

Due to thermal expansion, the global sea level rose 0.23 inches in 2024. This occurred as warmer water expanded after winds mixed heat deeper than usual. According to scientists’ estimates, two-thirds of the rise came from warming oceans rather than melting ice.  

Sea level rise is also accelerating, based on the long record that includes Sentinel-6 data. It shows the sea level rising from 0.08 inches/year in 1993 to 0.18 inches/year in 2023. Greenhouse gas-driven warming and ice melt are to blame as they have added water. This created a faster baseline for weekly changes.

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  • Your conclusion is wrong.

    The CO2 rise is due to the melting ice. The global warming is a natural event based upon the planet coming out of the last ice age.

    There is no verifiable data that supports human CO2 generation as causing the current levels of global warming.

    The rise in sea levels is only temporary.

    As the atmosphere warms it will absorb most of the added water and raise humidity levels worldwide.

    You will also get a more consistent rain fall rate worldwide, which will increase the amount of arable land.

  • in reply to DAB

     Having lived through what was supposed to be the second coming of the Ice Age (late 1970's) and global warming... I subscribe to the belief that weather/warming/cooling/etc is cyclic.  The fact that archeologists are investigating settlements revealed by the retreating ice tells me that we have been "here" before.
    Alas, we can't stop people from wanting their 15 minutes of fame.
    (That's not a ding on  .  He just shares the news.  He doesn't create it.)

  • in reply to kmikemoo

    When I did my research into "global warming", I found that the earth is currently in a roughly 100,000 year cycle that looks to have started just after the last big eruption at Yellowstone, though I am not sure if that was the cause.

    The ice core data confirms this cycle, so the current temperature levels on the planet are following the cycle very closely, which is why I dismiss the "humans" are at fault. The deviation is well within measurement tolerances.

    There is clearly no reason to panic, the process is relatively slow, we will not reach warm earth conditions for another 35,000 years or so before the cycle reverses and we go back to cold earth.

    I found a great paper by a Polish Geologist who actually studied how CO2 is captured by the building of glacier ice. His explanation was proven about 10 years ago when NASA put up a satellite to map CO2 concentrations around the world. The EcoNAZI's expected the data to show the cities that were contributing to global warming by generating CO2. What the data showed was that the highest concentrations of CO2 were at the poles where the melting ice was finally releasing Millenia old CO2 just as the geologist had predicted. NASA quietly downplayed the data because it did not fit the political agenda for which it was launched.

    I appreciate Cabe putting these stories out so I can keep reminding people about the truth.

Comment
  • in reply to kmikemoo

    When I did my research into "global warming", I found that the earth is currently in a roughly 100,000 year cycle that looks to have started just after the last big eruption at Yellowstone, though I am not sure if that was the cause.

    The ice core data confirms this cycle, so the current temperature levels on the planet are following the cycle very closely, which is why I dismiss the "humans" are at fault. The deviation is well within measurement tolerances.

    There is clearly no reason to panic, the process is relatively slow, we will not reach warm earth conditions for another 35,000 years or so before the cycle reverses and we go back to cold earth.

    I found a great paper by a Polish Geologist who actually studied how CO2 is captured by the building of glacier ice. His explanation was proven about 10 years ago when NASA put up a satellite to map CO2 concentrations around the world. The EcoNAZI's expected the data to show the cities that were contributing to global warming by generating CO2. What the data showed was that the highest concentrations of CO2 were at the poles where the melting ice was finally releasing Millenia old CO2 just as the geologist had predicted. NASA quietly downplayed the data because it did not fit the political agenda for which it was launched.

    I appreciate Cabe putting these stories out so I can keep reminding people about the truth.

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