[INTERPOSING VOICES]

TRISH QUINN: So to your point, yeah, [INAUDIBLE] aerosol measurements all over the world for 30 years, and we have the largest global database of measurements of aerosol properties, which are used as [INAUDIBLE] by aerosols. 

So I'm going to talk about work that we've done over the past five years, looking also, [INAUDIBLE] was talking about, looking at impact of marine ecosystems on the atmosphere. 

So why focus on marine ecosystems and their impacts? Clouds and aerosols continue to contribute the largest uncertainty to estimates of the Earth's changing energy budget. And in particular, the uncertainties in emissions of natural aerosols, including sea spray and biogenic sulfate, account for half of the variance of aerosol forcing since 1750. So reducing uncertainties in climate forcing estimates requires a better understanding of the role of natural aerosols. 

Since we're all on the same page about aerosol particles, clouds don't form without aerosol particles. Aerosol particles that take up water and nucleate to form cloud droplets are called cloud condensation nuclei, or CCN. And these CCN can impact cloud albedo, lifetime, and extent. And this is a satellite image, not of natural aerosol but of ship tracks. 

So emissions from the ships are getting mixed up at cloud height. Those particulates are taking up water, and needing to [? dry ?] in areas of the cloud. So there's basically two different ways you can have a connection between the marine ecosystem and cloud condensation nuclei or CCN. One is through dimethyl sulphide, which is a byproduct of phytoplankton [INAUDIBLE] ocean. But dimethyl sulphide or DMS is emitted to the atmosphere, where it's oxidized to form sulfate particles. So it's a biogenic origin of sulfate [INAUDIBLE]. Sulfate is a very good on CCN. 

The other method is through wind-driven production of aerosol in the sea surface, which dissolves in sea spray aerosol [INAUDIBLE] inorganic sea salt and organics. 

So what we have been trying to do is, determine the contribution of biogenic sulfate versus sea spray to the marine boundary layer of CCN population. 

And we're doing this as part of the North Atlantic Aerosol Marine Ecosystem Study, which is a five-year NASA Earth Adventure product. And we receive funding from NSF and NASA for it. And it's focused on the North Atlantic because it's the largest plankton bloom in the ocean. There's large spatial and seasonal variability. And when you have a very [INAUDIBLE] view of continental sources of aerosol, and it's very clean marine conditions, you can find an opportunity to detect impacts of the bloom on aerosol properties. 

So these are the five different cruises we did in this region. They were timed to target different phases of the plankton bloom. And there was quite a bit of variability in plankton community composition and concentration, the degree of physiological stress, as well as chlorophyll concentration. 

I'm just going to show, basically, one result slide. So this is looking at these three different chemical composition of aerosols, that you can get from the ocean. One is biogenic sulfate, organics and inorganic sea salt, which is the concentration of those three different components versus the CCN concentration. If you look over all seasons at the different [INAUDIBLE] the different experiments and the different seasons, you really only find correlation between biogenic sulfate and CCN. We don't find anything with organics. And if you look at the whole year, all the year, you don't see much of the inorganic sea salt. 

But if you look at just the names, one which is November Cruise, and blow that up, you can see that you do see a correlation between sea spray aerosol and CCN. So sea salt is only important in November, when the wind speeds were high and there was very few phytoplankton biomass. 

This is just another way of looking at the same result. This is another fraction of CCN in the four different seasons. Sulfates in red and sea sprays in blue. 

So only in November, again, do you see a significant contribution of sea spray. The rest of the year is due to biogenic sulfate. 

And this result is not just for the North Atlantic. Like I said, we've been making measurements all over the world's oceans. So these are the cruises where we had pretty remote, clean conditions. And we see the same result, that sea spray makes up a small fraction of the CCN's population globally. 

So just to sum up, it's biogenic sulfate that's providing the link between marine ecosystems and aerosol and cloud properties. So reducing uncertainties in aerosol climate forcing, requires improved understanding of the factors that control the emission of DMS, and then the formation and loss of biogenic sulfate. Thank you.

[APPLAUSE]