How tiny aerosols in sea spray influence Earth's climate

When you feel that salty breeze caress your face at the beach, you may not think of how it’s traveling all the way from the ocean surface to high up in the atmosphere. Given a shove by breaking waves, particles known as sea spray aerosols are flung up into the air and can travel kilometers skywards.

Believe it or not, these tiny particles have a big job. They’re key players in Earth’s radiative balance – the delicate dance between the energy our planet absorbs, emits, and reflects.

The balance can impact our climate significantly. Mostly made up of salt, and sprinklings of other chemical compounds, these sea spray aerosols also carry along biologically produced proteins and sugars. Yes, these particles have had a slice of life.

Sea spray aerosols: Earth’s salt shakers

The story of how life from the ocean can alter these aerosols and by extension, our environment, is as intriguing as it gets. How? By tweaking their dimensions, concentration, chemistry, and their propensity to soak up water.

You would think with such a big role, we would know a lot about them. Turns out, our knowledge on the average levels of organic content in sea spray has been a bit foggy.

Michael J. Lawler and his team at the National Oceanic and Atmospheric Administration (NOAA) have now put some pieces of the puzzle together.

Pulling data from four deployments of the NOAA Particle Analysis by Laser Mass Spectrometry (PALMS) instrument, the researchers set sail on NASA’s Atmospheric Tomography (ATom) mission. The team conducted experiments in the Atlantic and Pacific Ocean between 2016 and 2018.

Organic components of aerosols

So, how does life influence the composition of these aerosols? PALMS provided the answer by measuring the mass of organic molecules in the sampled aerosols.

The researchers found that, most of the time, the organic mass fraction of sea spray aerosols is low, typically less than 10 percent. However, the smaller the particle, the higher the proportion of organics it harbors.

One might expect the organic mass fraction to change with the seasons, mirroring the fluctuating abundance of ocean life. Surprisingly, they found little seasonal variability, except for a couple of outliers in the Canadian Arctic and the southern middle to high latitudes.

The study also uncovered a much larger organic component residing higher in the troposphere, which they attribute to atmospheric chemical reactions rather than the original mix churned up by the ocean waves.

Role of sea spray aerosols in climate

Understanding the dynamics of sea spray aerosols is not merely an academic exercise; it holds profound implications for climate science. These tiny particles serve as nuclei around which cloud droplets can form, directly affecting cloud properties and behaviour.

As clouds reflect sunlight back into space, a crucial factor in regulating Earth’s temperature emerges, demonstrating the interconnectivity of oceanic and atmospheric systems. Furthermore, the biological material within these aerosols can influence cloud microphysics and precipitation patterns.

Thus, deciphering the complexities of sea spray aerosols contributes to our larger understanding of climate change and its myriad influences.

Next wave of research

Like a wave that leaves behind prints on the sand, this research opens up fresh avenues of inquiry. What role do organic molecules play in the creation of tiny sea spray aerosols smaller than 0.2 micrometers? How can we better harmonize observations and numerical models of organics in sea spray aerosols?

Lawler and his team’s work has provided a glimpse into the complex relationships between ocean, atmosphere, and life. But there’s still a whole ocean of knowledge waiting to be discovered.

So, the next time you’re at the beach, remember to give a nod to the unsung heroes of our climate – the humble sea spray aerosols.

As you feel the salty breeze on your face, think about how these tiny particles journey from the foaming waves to the distant corners of the atmosphere, carrying a little taste of ocean life with them.

And perhaps, say a little thank you. Because these tiny particles, with their big job, are working hard to maintain the delicate balance of our planet, one wave at a time.

The study is published in the journal AGU Advances.

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