TORONTO – Could wave height in freezing water have something to do with ice formation in clouds? According to a new analysis of the trip of a research vessel in the Chukchi Sea, there may be a connection, which could help make climate models more accurate.
As global warming melts more sea ice in the Arctic region, it allows stronger winds to lift higher waves, sending spray high into the air. The new study, published last month in the journal Geophysical Research Letters, examines how particles thrown by waves could promote the development of ice-forming clouds.
Cloud formation, and how exactly it occurs, is an important part of weather systems and helps us understand how to track what’s called the surface heat balance: how much heat is needed to raise the temperature of a respective body of water from its minimum winter to its summer maximum. This surface heat balance then informs the climate models that researchers use to track climate change.
“The knowledge gained from this study is very important if we are to accurately predict the effects of global warming on the Arctic,” a press release said.
This new study examines data collected in November 2018, by a research vessel during an arctic cruise in the Chukchi Sea, north of the Bering Strait. The ship was making meteorological observations and analyzing the different types of organic particles that the spray throws into the air from the peak of the waves.
In order to take these measurements, the ship’s researchers launched particle sensors into the clouds using balloons. They also took measurements at different depths of the ocean itself to understand how the roughness of the ocean on any given day relates to weather conditions and ocean particles interacting with clouds.
The particles they were most interested in are called ice nucleated particles (INP). These are particles that essentially act like “seeds” in the sky, promoting the growth of ice in clouds by freezing the droplets.
During the voyage of the research vessel, there were different meteorological phases. During the first phase, the winds picked up, but the air temperature was also “reasonably high”. The air temperature decreased over a period of three days. During a two-day period later in the research, the wind speed peaked, but the air temperature and water temperature sometimes differed by up to 10 degrees.
“The sea surface temperature during this month was a record high, which contributed to the delay in the advance of sea ice in this area,” said the study.
The study found that during these high wave conditions, there was a higher concentration of INP, which “corresponded to greater amounts of ice crystals in lower level clouds.” Under these conditions, the concentration of INP was multiplied by 10 compared to previous periods.
When the researchers analyzed the aerosols themselves, they found “a large amount of [organic carbon] associated with a high sea salt content ”, suggesting that a major source of NPIs found in clouds is the spray itself.
The Chukchi Sea itself is also a “marine biological hot spot,” the study pointed out. It is relatively shallow and has well-mixed ocean layers, in which particles closer to the bottom can be attracted to the surface under harsh conditions.
The statement said the discovery brings researchers closer to understanding what promotes the formation of ice clouds, which are an important part of understanding arctic weather.
“Ice clouds reflect much less shortwave solar radiation than water clouds, and therefore cloud phase greatly affects the surface heat balance of polar regions.” , indicates the press release. “They can also increase the amount of snow, which in turn positively affects the formation of sea ice.”
More studies are needed to take a more in-depth look at how the cycle works and how climate change interacts with it, but researchers say it brings us one step closer.
“Understanding the relationship between cloud formation and the new sea state resulting from the recent decline of sea ice in the Arctic is essential for skillful weather and sea ice forecasting, as well as for climate projections. futures ”, Jun Inoue, with the National Institute of Polar Research. in Japan, the statement said.