Meltwater profiling can help predict Arctic sea ice changes

Due to global climate change, sea ice levels in the Arctic ocean are decreasing quickly. However, monitoring sea ice has been difficult due to environmental conditions such as high winds and shifting distribution. 

An international team of researchers led by Japanese scientists has compiled data collected during the MOSAiC observational expedition to analyze the ice-ocean boundary layer (IOBL) as it melted and refroze. With this data, they were able to calculate the rate of growth and decline of sea ice. 

“Owing to the complex patterns of heat and energy transfer, the physics of the cold oceans is complicated,” said study lead author Dr. Yusuke Kawaguchi of The Atmospheric and Ocean Research Institute at The University of Tokyo.

“Our objective was to quantify the thermodynamic growth and decay of the sea ice while incorporating effects of heat and salt exchange with near-surface water due to turbulent forces.”

By observing the sea from various angles and using data from the MOSAiC, they determined that more ice was melting in the summer. 

“Our first discovery was that in the summer, strong winds cause the mixing of water where the ice and ocean meet. We were able to show that enhanced heat transfer occurs right below the sea ice,” explained Dr. Kawaguchi.

The experts also found that due to more ice melting, there was a drop in oceanic salinity, which caused changes in the point when ice refroze.

“As melt water accumulates beneath the sea ice, salinity of sea water decreases and then the freezing temperature increases. This terminates the melting of sea ice at an earlier timing because water gets easier to freeze,” said Dr. Kawaguchi.

The team is looking forward to continuing their work with the hopes of creating an instrument that will simultaneously measure sea ice movement and salinity at the IOBL. With that simultaneous data, researchers will have a more accurate view of what the ice is doing. 

“The extent of the Arctic sea ice may affect the regional climate in distant places, like Japan, via atmospheric disturbances. We believe that studying the sea ice will allow us to better predict future changes in the Earth’s climate.”

This study is published in the Journal of Geophysical Research-Oceans.

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By Erin Moody , Earth.com Staff Writer