- 3220 - EARTH - rising sea levels? The ocean absorbs more than 90% of the heat trapped by the planet due to the increasing concentrations of greenhouse gases in the atmosphere. As the water heats up, its volume expands, causing sea-level rise. As the planet warms, the melting ice sheets add further height.
------------------ 3220 - EARTH - rising sea levels
- The new ocean-monitoring satellite “Sentinel 6 Michael Freilich” has started delivering ultra-precise measurements of rising sea levels on Earth.
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- As the globe's climate changes, Earth's oceans are warming, expanding and rising. To keep a watch on the waters, scientists have been relying for three decades on satellites that closely track how sea levels are behaving around the world. And the latest such satellite, Sentinel 6 in 2021 has just begun to send back data.
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- The spacecraft, named after the late NASA climate scientist Michael Freilich, lifted off from Vandenberg Air Force Base in California last November. Sentinel 6 will be able to give scientists more precise data about ocean surfaces than its predecessors, accurate to only a few centimeters. As a result, it'll allow meteorologists to better track weather patterns, such as hurricanes and accurately monitor temperatures and rising sea levels.
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- Sentinel-6 is the latest launch in a proud lineage of ocean-watching satellites that began in 1992 with “TOPEX/Poseidon“. This satellite first enabled scientists to observe processes in the oceans on a global scale with a regular frequency.
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- The “Jason series’ soon followed: three satellites that launched in 2001, 2008, and 2016, respectively. Jason 3, the last of these, is still hard at work measuring sea levels and helping weather forecasters.
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- Sentinel-6 now trails Jason-3 by 30 seconds in their orbits together at an altitude of 830 miles . The two satellites scan 90% of the world's oceans at regular intervals. Scientists then compare data from the two satellites to ensure that Sentinel-6 is up to the task before it takes over from Jason-3 as the main sea level monitoring craft.
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- Sentinel-6’s main improvement over its predecessor is its advanced altimeter, called Poseidon-4. Based on synthetic aperture radar (SAR) technology, Poseidon-4 takes more precise measurements than conventional radar altimeters thanks to its ability to analyze the Doppler effect of the radar signal as it bounces off the sea surface and returns to the spacecraft.
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- Doppler effect is the shift in the frequency of the signal emitted by a moving source as it moves toward and away from the recipient.
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- To manage the transition from Jason-3's lower resolution measurements to Sentinel-6's high-resolution measurements with confidence, the Poseidon-4 altimeter acquires both conventional low-resolution measurements simultaneously with high-resolution synthetic aperture radar measurements.
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- Two streams of data from Sentinel 6 are now available to the global weather forecasting community, providing information about the sea surface height with accuracies of 2.3 inches and 1.4 inches respectively.
- Later this year, 2021, even more precise data sets, accurate to 1.2 inches, will be released to climate researchers.
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- Sentinel-6 won't be the last of its kind. A twin satellite, Sentinel-6B, is scheduled to launch in 2025. The two Sentinel-6 satellites will ensure that scientists will keep receiving the most accurate data about sea levels in the fourth decade of satellite measurements.
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- The ocean absorbs more than 90% of the heat trapped by the planet due to the increasing concentrations of greenhouse gases in the atmosphere. As the water heats up, its volume expands, causing sea-level rise. As the planet warms, the melting ice sheets add further height.
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- As a result, many low lying coastal areas all over the world already face frequent flooding with some potentially becoming uninhabitable in the future. The Sentinel-6 duo will help scientists better predict what awaits communities in the at-risk regions in the future.
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- These initial data show that Sentinel-6 Michael Freilich is an amazing new tool that will help to improve marine and weather forecasts. It s a good investment don’t you think? But, we are just getting our feet wet.
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- July 14, 2021 EARTH - rising sea levels 3220
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