Going with the floe: Sea ice movements trace dynamics transforming the new Arctic

November 14, 2019

Climate change is accomplishing what centuries of exploration could not: opening the fabled Northwest Passage, a maritime shortcut from Europe to Asia via the Arctic Ocean.

Research led by the University of California, Riverside, could help ships navigating these freshly thawed routes avoid the Titanic's fate with a new way to forecast the motion of floating ice.

A group led by Monica Martinez Wilhelmus, an assistant professor of mechanical engineering in the Marlan and Rosemary Bourns College of Engineering, is the first to use moderate resolution imaging spectroradiometer, or MODIS, satellite imagery to understand long-term ocean movements from sea ice dynamics.

MODIS sensors aboard NASA satellites have been collecting daily images of arctic ice floes -- large, flat sheets of floating ice -- for over 20 years, but using them to study how they move with ocean currents has been a laborious task. Clouds often obstruct the view and floes must be identified and marked by hand.

The engineers used image-processing algorithms to remove clouds, sharpen details, and separate individual floes. They then used image analysis algorithms to map the movement of floes over a period of days. The resulting ocean current maps were about as accurate as maps made using more labor-intensive traditional methods. Tracking sea ice will help scientists better understand the sources driving sea ice transport.

"No one had bothered before to use MODIS because the satellite is sensitive to clouds and it's hard to identify ice," Martinez said. "Our algorithm automatically filters clouds and uses other image processing algorithms that give the velocity and trajectory of the ice floes."

The analysis will help researchers quantify how the interactions between ocean currents, climate, and sea ice have changed in the last two decades. This will ultimately improve ocean models, which for the most part, do not resolve at the scales necessary to study these interactions.

"MODIS data is one of the longest records of earth ever compiled," said first author Rosalinda Lopez, a graduate student in Martinez's lab. "This means that we are able to expand our analysis to almost two decades to observe the variability of sea ice as dramatic changes transform the region."

The rate at which ice spreads apart affects how fast it melts. Ice that rapidly spreads away from other ice melts more quickly than ice that stays close together, similar to how a handful of ice cubes in a glass of water will melt more slowly than a handful of ice cubes in a bathtub.

This affects how fast and how much fresh water from the ice blends into the salty sea water, which in turn affects how the ocean current moves.

"Adding fresh water to the sea water affects its energetics, which affects the current," Martinez said. "We need to understand how ice interacts with the ocean."

With the Arctic melting faster than ever, it's important to learn how ocean currents are changing. Ocean currents are intimately associated with the climate, and a better understanding of long-term currents will help improve models of climate change.

"This is a new field," Martinez said. "No one knows how the ice is going to behave."

The altered currents will also affect Arctic communities that depend on hunting and fishing. As their economies falter, ships will need to find safe ways to deliver supplies to help them survive. Proposed oil drilling in the Arctic could also mean oil spills, and the UC Riverside technique could help predict how oil slicks would behave.
The paper, "Ice Floe Tracker: An algorithm to automatically retrieve Lagrangian trajectories via feature matching from moderate-resolution visual imagery," is published in the journal Remote Sensing of Environment. In addition to Martinez and Lopez, the paper was co-authored by Michael Schodlok, a scientist at NASA's Jet Propulsion Laboratory.

University of California - Riverside

Related Climate Change Articles from Brightsurf:

Are climate scientists being too cautious when linking extreme weather to climate change?
Climate science has focused on avoiding false alarms when linking extreme events to climate change.

Mysterious climate change
New research findings underline the crucial role that sea ice throughout the Southern Ocean played for atmospheric CO2 in times of rapid climate change in the past.

Mapping the path of climate change
Predicting a major transition, such as climate change, is extremely difficult, but the probabilistic framework developed by the authors is the first step in identifying the path between a shift in two environmental states.

Small change for climate change: Time to increase research funding to save the world
A new study shows that there is a huge disproportion in the level of funding for social science research into the greatest challenge in combating global warming -- how to get individuals and societies to overcome ingrained human habits to make the changes necessary to mitigate climate change.

Sub-national 'climate clubs' could offer key to combating climate change
'Climate clubs' offering membership for sub-national states, in addition to just countries, could speed up progress towards a globally harmonized climate change policy, which in turn offers a way to achieve stronger climate policies in all countries.

Review of Chinese atmospheric science research over the past 70 years: Climate and climate change
Over the past 70 years since the foundation of the People's Republic of China, Chinese scientists have made great contributions to various fields in the research of atmospheric sciences, which attracted worldwide attention.

A CERN for climate change
In a Perspective article appearing in this week's Proceedings of the National Academy of Sciences, Tim Palmer (Oxford University), and Bjorn Stevens (Max Planck Society), critically reflect on the present state of Earth system modelling.

Fairy-wrens change breeding habits to cope with climate change
Warmer temperatures linked to climate change are having a big impact on the breeding habits of one of Australia's most recognisable bird species, according to researchers at The Australian National University (ANU).

Believing in climate change doesn't mean you are preparing for climate change, study finds
Notre Dame researchers found that although coastal homeowners may perceive a worsening of climate change-related hazards, these attitudes are largely unrelated to a homeowner's expectations of actual home damage.

Older forests resist change -- climate change, that is
Older forests in eastern North America are less vulnerable to climate change than younger forests, particularly for carbon storage, timber production, and biodiversity, new research finds.

Read More: Climate Change News and Climate Change Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.