In the Arctic, much depends on ice. Pack ice. Drift ice. Old ice. New ice. For some wildlife, ice provides safe haven from predators and for others, it offers access to prey. For humans, many of whom are living in isolated coastal communities with no roads in or out, ice is everything.
Sailors and explorers have kept sporadic records about ice conditions dating back thousands of years, but only since 1979, with the launch of Earth observing satellites, have streams of near-constant information about Arctic sea ice been available. Using images and observations captured daily, scientists are able to measure ice thickness, area of coverage, and seasonal fluctuations in the advance and retreat of ice coverage.
Real-time sea ice images and data are vital for the safety of researchers like George Divoky and for people in Arctic communities who depend on ice for subsistence hunting and fishing. Anthony Fischbach is a wildlife biologist for the United States Geological Survey (USGS) in the Alaska Science Center Walrus Research Program, where he has worked since 1994. Fishbach delivers a daily “Ice Mail” to just over 100 people interested in up-to-date information on Arctic sea ice. Subscribers include Divoky, scientists in Russia, and remote Inuit communities who may not have easy access to internet connections capable of retrieving large amounts of data.
“The main niche I’m trying to fill is a way to get meaningful sea ice imagery and charts in the palm of your hand or on the deck of a ship where you’ve got really minimal bandwidth,” said Fischbach. “If you’re in a remote community that has 2G cell phone connection or if you’re on an Iridium-linked vessel, the existing ways of accessing the data just don’t meet the need.”
He described his own experiences of working in Arctic coastal communities or being on board a retrofitted crabber, “We just struggled to get the data through the existing methods and we couldn’t get all the data we wanted.”
Today, Fischbach relies heavily on two satellites we’ll be following closely this summer — Aqua and Terra. Both are part of NASA’s Afternoon Constellation or A-Train, which is a convoy of satellites operated by NASA and international partners. The satellites travel together, completing a polar orbit twice a day; because of the Earth’s rotation, a polar orbit means that the satellites will observe the entirety of the planet’s surface every one to two days.
The A-Train crosses the equator at about 1:30 a.m and 1:30 p.m.; the Terra satellite passes the equator in the early morning, Aqua in the afternoon. This timing and repetition allows scientists to generate cloud-free images and to study how temperatures over land and water change from day to day.
By flying satellites loaded with a host of Earth-observing instruments in a formation, scientists are able to gather a great deal of meaningful data. According to NASA, flying in concert “allows for synergy between the missions—synergy means that more information about the condition of the Earth is obtained from the combined observations than would be possible from the sum of the observations taken independently.”
While each satellite is tasked with different mission objectives, the data from individual instruments can be combined to paint a more vivid and informative picture of the Earth’s climate and atmospheric systems.
This visualization shows the orbits of NASA-related near-Earth science missions that are considered operational as of March 2017. Video Credit: Greg Shirah for NASA Visualization Studio
A key instrument on board Aqua and Terra is a moderate resolution imaging spectroradiometer, or MODIS for short, which is capable of of observing across 36 spectral bands or wavelengths at different resolutions (250, 500, and 1000 meters). (A complete technical profile of this instrument and the data it provides can be found here.)
MODIS is an integral instrument for studying the ocean, because it aids in the creation of ocean color maps. Ocean color reveals much about phytoplankton productivity, which, according to NASA, forms the basis of the ocean’s food chain and plays a big part in carbon storage and movement. MODIS also allows for detailed maps of sea surface temperatures, which are known to influence weather patterns. Since MODIS is able to study water in liquid, solid or gas form, the instrument aids measurement of snow and sea ice and how much solar energy is being absorbed or reflected back to space.
Fischbach explains that the images in his daily emails (seen above) are processed with false color so you can distinguish the white of the clouds with the white of the sea ice; sea ice is aqua-colored and the clouds appear white. The images show detail down to 250 meter resolution, meaning you can clearly see objects that are 250 meters or 820 feet wide.
To people living and working in the the Arctic, these sea ice data could be comparable to monitoring hazards on roadways in the lower 48, because the ice and water provide access for both transportation and food.
The ice is moving constantly, which creates precarious decision-making choices in remote regions without the right information. With several days of ice data in hand, people in the field like Fishbach and Divoky can make better choices.
“I’d really like to know as much as I can about how the ice is moving. Is there more ice coming this way? Is it going to be congesting? Is it going to be opening up?” he asks. “You know, do I launch boat out in to the ice — the shifting seascape — where I could get pinned in and trapped and not make it home?”
This story is part of an ongoing series titled Arctic Change centered around George Divoky’s 44th field season studying Black Guillemots, sea ice, and climate change on a remote Arctic island off the coast of Alaska. To donate and support Divoky’s work on Cooper Island, visit the Friends of Cooper Island.
Arctic Sea Ice By NASA Earth Observatory
50 Years of Earth Observation by European Space Agency
Monitoring Sea Ice by NASA Earth Observatory