Staying Afloat: Using Jason-3 to Measure Sea-level Rise

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The joint U.S. and European Jason-3 mission may help coastal regions in countries like Vietnam prepare for sea level rise associated with climate change.

NOAA aviators used remote-sensing cameras to provide before and after images to aid in damage assessment in Louisiana floods in August 2016. This image is from Port Vincent. Image Credit: NOAA Ocean Service

NOAA aviators used remote-sensing cameras to provide before and after images to aid in damage assessment in Louisiana floods in August 2016. This image is from Port Vincent. Image Credit: NOAA Ocean Service

Before and after images tell a story of a once-thriving community, now underwater. Homes where memories were made are being washed away. Will it happen again?

The deadly flooding in Louisiana during August 2016 is one tragic example of what many regions are experiencing ‰ÛÒ some for the first time. Scientists believe climate change will deliver more flooding and increasingly severe storms around the world.

Is everyone on Earth experiencing climate change at the same rate? If you ask NASA Jet Propulsion Laboratory (JPL) oceanographers Joshua Willis and Bill Patzert, they would simply say ‰ÛÏno.‰Û Willis is project scientist for Jason-3, a U.S. and European satellite mission that measures the height of the ocean’s surface. Patzert is a climatologist involved with altimetry missions that began with TOPEX/Poseidon in 1992, followed by Jason-1, Jason-2 and, recently, Jason-3.

‰ÛÏSome regions are warming more rapidly than others,‰Û said Patzert. And, this warming impacts the behavior of our oceans. ‰ÛÏThe unequivocal proof of global warming is sea level rise,‰Û Patzert adds. ‰ÛÏSea levels are rising. Beaches are shrinking. Coastlines all around the planet will have to be remapped.‰Û

Jason-3 is an oceanographic satellite, which uses a radar altimeter to accurately measure the height of the ocean over the Earth — or in other words, the sea level.

The other primary instruments on board include the Advanced Microwave Radiometer (AMR), DORIS, GPS Receiver, and Laser Retroreflector Array (LRA). These instruments allow the satellite to measure variables such as sea level, wave height, and ocean surface wind speed.

Scientists are using Jason-3 to gain a better understanding of the oceanographic dynamics between sea level rise and human activity. Willis says this will give the ‰ÛÏnext five years of data rather than the past five years of data.‰Û This allows scientists to measure the differences between today‰Ûªs climate and yesterday‰Ûªs, and monitor the human impact on sea level rise due to climate change.

Patzert retells the story of sea level rise simply: the agricultural and industrial revolution led to a dramatic increase in greenhouse gas levels in the atmosphere. These gases trap heat on the Earth‰Ûªs surface, which causes the Earth to absorb more heat on its surface than what is radiating back into space.

‰ÛÏThe atmosphere and the land have very little heat capacity,‰Û said Patzert. ‰ÛÏ95 percent of the heat, due to excess warming from greenhouse gases, is going into the oceans. The oceans are the great flywheel of the climate system.‰Û When oceans absorb this heat, it causes the oceans to expand. This is one factor contributing to sea level rise.

Anthropogenic activitiesåÊcontributingåÊto climate change and sea level rise, are especially concerning for coastal communities.

Vietnam, home to more than 90 million people on the Indochina Peninsula, could be impacted by sea level rise more than any country in East Asia, as stated in a recent study by Pham Thi Thuy Hanh and Masahide Furukawa from the Bulletin-College of the University of the Ryukyus.

Hanh and Furukawa suggest in the study that sea level rise in Vietnam could flood ‰ÛÏwetlands and lowlands, erode shorelines, exacerbate coastal flooding, increase the salinity of estuaries and aquifers and otherwise impair water quality and impact coastal ecosystems.‰Û

According to Issac Boateng, senior lecturer of coastal engineering at the University of Portsmouth in England, ‰ÛÏ(Vietnam‰Ûªs) coastal ecosystems are highly vulnerable due to ‰Û_ climate change and associated sea level rise. Irregular exploitation and human activities such as environmental pollution, mangrove logging for shrimp farming and fuel-wood intensify these natural impacts.‰Û

Flooding in Hong Ngu township, Dong Thap province of Vietnam. Image Credit: Evangelos Petratos EU/ECHO

Flooding in Hong Ngu township, Dong Thap province of Vietnam. Image Credit: Evangelos Petratos EU/ECHO

Willis and Patzert argue that sea level rise poses a serious threat to millions of people. Even people who do not live near coastlines are at risk, because of the ‰ÛÏdependency of the world economy on all the great ports where commerce is conducted across the planet.‰Û

To Willis, another danger of sea level is that ‰ÛÏit creeps up on you. The slow rise of the water itself is not what usually causes people to retreat from the coast.‰Û This change is often subtle until it becomes a nuisance to everyday life. ‰ÛÏWhat happens is that the storm surge that was too small to reach your home, now reaches your home. The high tide that didn‰Ûªt flood this street, now floods this street,‰Û said Willis. Places like Vietnam, Florida, Louisiana, and other coastal areas around the world are beginning to face this reality.

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Jason-3 satellite orbiting the Earth. Image Credit: Courtesy NASA/JPL-Caltech

 

This is why the Jason-3 mission is important to the global community at large. Willis explains, ‰ÛÏHundreds of millions of people live in areas that will be affected by sea level rise and those places have a big impact on our economy.‰Û Patzert adds that about 50 percent of the planet lives within 50 miles of a coastline, further emphasizing the severity of the problem.

According to Willis, one function of Jason-3 is to measure the height of the ocean. By doing this, scientists and the public can see how much humans are changing the climate. ‰ÛÏThe oceans play a huge role in our climate, (and the satellite) gives a bird‰Ûªs eye view of how the oceans are changing all around the planet every 10 days. It shows the long-term rise of the oceans as the planet warms up,‰Û said Willis.

By extending the current record on sea level rise, scientists are able to monitor how the oceans are behaving. As Willis points out, this is important to the Earth observing community because it shows ‰ÛÏthe height of the ocean today versus 20 years ago.‰Û These measurements will give people living in vulnerable locations insight about current sea level trends, and how to approach the future in a continuously warming world.

Timmera Whaley participated in Earthzine‰Ûªs 2016 summer Writing Club and is a graduate student in the environmental science program at Tuskegee University in Tuskegee, Alabama.