On July 7, 2021, NASA sent two robotic explorers to the Arctic to collect sea surface temperature data and improve estimates of ocean temperatures in that region. Pairing up with Saildrone, a designer and manufacturer of non-crewed surface vehicles or USVs, researchers hope to use the results to better understand the impacts of climate change in the Arctic.
"The Arctic is one of those regions that's being very rapidly impacted by climate change," said principal investigator Chelle Gentemann, a senior scientist at Farallon Institute in Petaluma, California. "We're all connected, so what happens in Siberia is going to affect what happens in California. And one of the keys to understanding and mitigating climate change is understanding what's going on in the Arctic, how fast it's changing, and how it's going to affect future weather."
Acting like Earth's refrigerator, Arctic climate and weather interact with the rest of the world. Over the past 30 years, the Arctic has warmed about twice as fast as the rest of the Earth. This type of warming can influence sea level rise, global ocean currents, and natural hazards like hurricanes. Researchers in the Arctic are investigating recent and past changes and how they influence other parts of the planet.
The Arctic is challenging to study because of its frigid tundra and sea ice dynamics. For years, climate researchers have relied on satellite remote sensing to measure key ocean properties, including ocean salinity, ocean temperature and air-sea interactions (for example, hurricanes). Satellite measurements are validated by collecting field data using buoys and research vessels. Yet in the Arctic, buoys are often destroyed by shifting ice and research vessels are expensive to operate.
"The problem is that almost all of our buoys are located along the coasts of the United States, Europe, near India and Asia and along the tropics. We aren't able to deploy and maintain buoys in the Arctic," Gentemann said. "We have to rely on satellite data to understand Arctic ocean temperatures and how they're changing with climate change."
Saildrone USVs, are autonomous sailboat-like vehicles powered by green technology; they are propelled by wind and use solar-powered sensors. These autonomous vehicles can be steered from computers hundreds of miles away, allowing them to access severe ocean environments, like the centers of hurricanes and shifting packs of sea ice in the Arctic. They provide a resilient and affordable means to validate satellite data and develop and improve algorithms that model changing temperatures.
The 2021 NASA Arctic Cruise is ongoing; the Saildrone USVs passed through the Bering Strait and are headed into the Chukchi Sea. In previous Saildrone missions, NASA researchers found close correlation between satellite remote sensing measurements of sea surface salinity and data collected by Saildrone.
"We have confidence in satellite information because we are also seeing similar things in the on-site measurements collected by Saildrone. This is encouraging. This tells you that we can use the satellite data to monitor what's happening over these long periods of time," said Jorge Vazquez, a scientist for NASA's Physical Oceanography Distributed Active Archive Center, or PO.DAAC. PO.DAAC is one of several NASA Distributed Active Archive Centers, which process, archive and distribute data collected from NASA projects.
The primary focus of the 2021 NASA Arctic Cruise is to validate sea surface temperature data from satellites, but scientists have also collected information on air-sea interactions, ocean stratification (different layers of water), ocean currents, sea surface salinity and the marginal ice zone (an area where ice forms seasonally and varies over an area) to answer other scientific questions.
The 2021 NASA Arctic Cruise is part the Multi-Sensor Improved Sea Surface Temperature project, or MISST. This is an international and inter agency collaboration aimed at improving weather and climate research and prediction by providing better-quality ocean temperature measurements from satellites. NASA satellites aid in this effort, and projects like the 2021 NASA Arctic Cruise validate NASA satellite measurements to further MISST's mission.
"What we're finding is that we live on a planet where you have to have a multidisciplinary and international approach to understand how this planet works. It's a team effort," Vazquez said.
NASA has an open data policy, and the 2021 NASA Arctic Cruise takes this one step further. The project has an open invitation for other researchers from around the world to be an observer on the mission, have access to near-real time data and participate in the conversation about the mission and science objectives. The Saildrone Arctic deployments are available through the PO.DAAC at http://podaac.jpl.nasa.gov.