Nav: Home

NASA study improves forecasts of summer Arctic sea ice

March 02, 2017

The Arctic has been losing sea ice over the past several decades as Earth warms. However, each year, as the sea ice starts to melt in the spring following its maximum wintertime extent, scientists still struggle to estimate exactly how much ice they expect will disappear through the melt season. Now, a new NASA forecasting model based on satellite measurements is allowing researchers to make better estimates.

Forecasts of how much Arctic sea ice will shrink from spring into fall is valuable information for such communities as shipping companies and native people that depend on sea ice for hunting. Many animal and plant species are impacted directly by changes in the coverage of sea ice across the Arctic. Uncertain weather conditions through spring and summer make the forecasting of Arctic sea ice for a given year extremely challenging.

With data from satellites, which have been measuring sea ice in the Arctic since 1979, scientists can easily calculate the downward trend in Arctic sea ice. To make forecasts of how the Arctic sea ice cover might behave in the upcoming year, researchers have several options. The simplest approach is to assume a continuation of the long-term trend into the current year. The problem with this approach is that it will miss outliers -- years when the sea ice cover will be a lot higher or lower than expected. Another option is to analyze the physical characteristics of the sea ice cover as the melt season develops, to try to more precisely estimate if the amount of sea ice come September will be more or less than expected from the long-term trend.

"What we have shown is that we can use information collected in the spring and onwards to determine if we should see more or less ice come the end of summer than expected from the long-term decline," said Alek Petty, lead author of the new paper, which was published on February 27 in the journal Earth's Future, and a sea ice researcher at NASA Goddard Space Flight Center in Greenbelt, Maryland.

The study used satellite measurements of sea ice coverage and melt onset. Petty's team found that the forecasts based on melt onset -- the time at which sea ice starts to melt and open water appears in the Arctic Ocean -- were most reliable in early spring, while sea ice coverage-based predictions were more reliable from June onwards. The forecasts focus specifically on regions that historically corresponded with how much sea ice remains come the September minimum extent. The predictions become more accurate with each passing month, as the model integrates more near-real-time information about sea ice melt and the distribution of open water areas across the Arctic Ocean and surrounding seas

To test whether their model produced reliable forecasts, Petty's team went back in time and made predictions for each year of the satellite record, using historical data of the Arctic sea ice conditions. They then evaluated the results against both the actual minimum extent for that year and what the long-term trend would have predicted.

"We found that our forecast model does much better than the linear trend at capturing what actually happened to the sea ice in any specific year," Petty said. "Our model is very good at catching the highs and the lows. The absolute values? Not exactly, but it tends to do very well at seeing when the sea ice extent is going to go up and when it's going to go down compared to what we might be expecting for that year."

Petty's research also showed that models can produce reliable forecasts of sea ice not only for the whole Arctic, but for concrete regions; specifically, the Beaufort and Chukchi seas north of Alaska.

"The state of sea ice has a large impact on the Alaskan hunting communities," Petty said. "If they know ahead of time what the sea ice cover is going to be like that year, they might be able to infer the availability of the species they hunt."

Future research will explore synthesizing different sea ice measurements into the same model to improve the reliability of the forecasts, Petty said.
-end-
For more information, visit:

http://www.nasa.gov/content/water-and-ice

NASA/Goddard Space Flight Center

Related Sea Ice Articles:

Melting sea ice may lead to more life in the sea
Every year an increasing amount of sea ice is melting in the Arctic.
Sea ice extent sinks to record lows at both poles
The Arctic sea ice maximum extent and Antarctic minimum extent are both record lows this year.
When the sea ice melts, juvenile polar cod may go hungry
Polar cod fulfill a key role in the Arctic food web, as they are a major source of food for seals, whales and seabirds alike.
NASA study improves forecasts of summer Arctic sea ice
The Arctic has been losing sea ice over the past several decades as Earth warms.
Melting sea ice may be speeding nature's clock in the Arctic
Spring is coming sooner to some plant species in the low Arctic of Greenland, while other species are delaying their emergence amid warming winters.
Sea ice hit record lows in November
Unusually high air temperatures and a warm ocean have led to a record low Arctic sea ice extent for November, according to scientists at the National Snow and Ice Data Center (NSIDC) at the University of Colorado Boulder.
My contribution to Arctic sea ice melt
Measurements reveal the relationship between individual CO2 emissions and the Arctic's shrinking summer sea ice.
See how Arctic sea ice is losing its bulwark against warming summers
Arctic sea ice, the vast sheath of frozen seawater floating on the Arctic Ocean and its neighboring seas, has been hit with a double whammy over the past decades: as its extent shrunk, the oldest and thickest ice has either thinned or melted away, leaving the sea ice cap more vulnerable to the warming ocean and atmosphere.
Tracking the amount of sea ice from the Greenland ice sheet
The Greenland ice sheet records information about Arctic climate going back more than 120.000 years.
Technique could assess historic changes to Antarctic sea ice and glaciers
Historic changes to Antarctic sea ice could be unravelled using a new technique pioneered by scientists at Plymouth University.

Related Sea Ice Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Digital Manipulation
Technology has reshaped our lives in amazing ways. But at what cost? This hour, TED speakers reveal how what we see, read, believe — even how we vote — can be manipulated by the technology we use. Guests include journalist Carole Cadwalladr, consumer advocate Finn Myrstad, writer and marketing professor Scott Galloway, behavioral designer Nir Eyal, and computer graphics researcher Doug Roble.
Now Playing: Science for the People

#529 Do You Really Want to Find Out Who's Your Daddy?
At least some of you by now have probably spit into a tube and mailed it off to find out who your closest relatives are, where you might be from, and what terrible diseases might await you. But what exactly did you find out? And what did you give away? In this live panel at Awesome Con we bring in science writer Tina Saey to talk about all her DNA testing, and bioethicist Debra Mathews, to determine whether Tina should have done it at all. Related links: What FamilyTreeDNA sharing genetic data with police means for you Crime solvers embraced...