One of the harshest and most dynamic regions on Earth is marginal ice area – The place where ocean waves meet sea ice, which is formed by freezing of the ocean surface.
Published today, a topical issue of the magazine Philosophical Transactions of the Royal Society A It reviews the rapid progress that researchers have made over the past decade in understanding and modeling this challenging environment.
This research is vital for us to better understand the complex interactions of Earth’s climate systems. That’s because the marginal glacial area plays a role in the seasonal freezing and thawing of the oceans.
Hard place to study
In the Arctic and Antarctica, ocean surface temperatures are constantly dropping -2℃ Cold enough to freeze, forming a layer of sea ice.
At higher latitudes near the poles, sea ice forms a solid cover several meters thick on the ocean that reflects sunlight, cooling the area and pushing cold water around the oceans. This makes sea ice a major component of the climate system.
But at lower latitudes, when the ice-covered ocean moves into the open ocean, sea ice forms into smaller, more mobile bits called “rafts” separated by water or a mass of ice crystals.
This marginal ice area interacts with the atmosphere above and the ocean below it in a very different way than the ice sheet closer to the poles.
It’s a challenging environment for scientists to work in, with a trip to the marginal ice region around Antarctica in 2017. Winds over 90 km/h And the Waves over 6.5 meters high. It’s also difficult to monitor from afar because the pontoons are smaller than most satellites can see.
Crushed by the waves
The marginal ice area also interacts with the open ocean via surface waves, which travel from open water into the area, affecting the ice. The waves can have a devastating effect on the ice sheet, by breaking up large buoys and leaving them more likely to melt during the summer.
By contrast, during the winter, waves can promote the formation of “pancake” rafts, so called because they are thin discs of sea ice (you can see them in the photo above).
But the energy of the waves themselves is lost during interactions with the buoys, so that the waves become progressively weaker as they travel deeper into the marginal ice zone. This results in wave and ice feedback mechanisms driving the evolution of sea ice in a changing climate.
For example, a trend to warmer temperatures will weaken the ice sheet, allowing waves to travel to the depths of the ice-covered oceans and cause further splitting, weakening the ice sheet – and so on.
Scientists who study marginal ice zone dynamics aim to improve our understanding of the region’s role in the dramatic and often confusing changes that the world’s sea ice is undergoing in response to climate change.
For example, in the Arctic Ocean, sea ice cover contains “It’s almost halved since the 1980sIn Antarctica, the sea ice sheet recently had one of them Larger And the smaller Recorded ranges, with the marginal ice area being one source of variability from year to year.
Our progress in better understanding these extreme regions has centered around large international research programs, run by the United States Office of Naval Research and others. These programs include earth scientists, geophysicists, oceanographers, engineers, and even applied mathematicians (like us).
Recent efforts have produced innovative observing techniques, such as a three-dimensional image wave method, buoyancy dynamics in the marginal ice area from aboard an icebreaker, and capturing waves in the ice from satellite images.
It also resulted in new models capable of simulating the interaction of waves and ice from a level Single rafts for the general behavior of full oceans. Australian developments prompted a multi-month, Australian-led experiment in the marginal ice region of Antarctica, on the new $500 million icebreaker. RSV NoinaWhich is expected next year.
The marginal ice area will be an increasingly important component of the world’s sea ice cover in the future, as temperatures rise and The waves get more extreme.
Despite rapid progress, there is still some way to go before understanding feedback processes in the marginal ice zone is translated into improved climate predictions used by, for example, IPCC assessment reports.
The inclusion of the marginal ice area in climate models has been described as the “holy grail” of the field by one of its leading figures, and the issue of the topic points to closer links with the broader climate community as the field’s next major trend.