Massive Flying Laboratory Uncovers Secrets of How Marine Life Influences Cloud Formation

View From DC-8 Research Aircraft

The view from the DC-8 research aircraft as flies through the marine boundary layer, the portion of the atmosphere close to the ocean’s surface where the ocean affects processes like cloud formation. Credit: Sam Hall

Ocean Life Helps Produce Clouds, but Existing Clouds Keep New Ones at Bay

Stand on the ocean’s shore and take a big whiff of the salt spray and you’ll smell the unmistakably pungent scent of the sea. That ripe, almost rotting smell? That’s sulfur.

Marine plankton breathe more than 20 million tons of sulfur into the air every year, mostly in the form of dimethyl sulfide (DMS). In the air, this chemical can transform into sulfuric

Gordon Novak

First author of the study Gordon Novak pictured with the National Oceanic and Atmospheric Administration chemical-sensing equipment used in the study. Credit: Courtesy of Gordon Novak

By reflecting sunlight back into space and controlling rainfall, clouds play significant roles in the global climate. Accurately predicting them is essential to understanding the effects of climate change.

“It turns out that this story of cloud formation was really incomplete,” says Tim Bertram, a UW–Madison professor of chemistry and senior author of the new report. “Over the last three or four years, we’ve been questioning parts of that story, both through laboratory experiments and with large-scale field experiments. Now we can better connect the dots between what’s emitted from the ocean and how you form these particulates that encourage cloud formation.”

With collaborators from 13 other institutions, Gordon Novak, a graduate student at UW­–Madison, constructed the analysis that was published October 11, 2021, in the Proceedings of the National Academy of Sciences.

A few years ago, this group of collaborators, led by Patrick Veres at NOAA, discovered that on its way to becoming sulfuric acid, DMS first turns into a molecule known as HPMTF, which had never been identified before. For the new study, the team used DOI: 10.1073/pnas.2110472118

This work was supported in part by the National Science Foundation (grants GEO AGS 1822420 and CHE 1801971), NASA (grants 80NSSC19K1368 and NNX16AI57G) and the U.S. Department of Agriculture (grant CA-D-LAW-2481-H).