Understanding Aerosols and Climate Impact

Aerosol particles can differ by their size and by their chemical composition and by

their shape. And all these inequalities can be mixed

together,

and that's what makes aerosols so difficult to study.

At any given location, particles of different types

and of different

origins can coexist. If a particle is, for example,

generated some way in China, it can be transported to the United States

of America.

So this transport from different places makes the aerosol population at

any given location extremely complex.

They have several roles in affecting climate.

For one, they simply reflect sunlight back to

space, and

this effect amounts to cooling of the atmosphere and of the surface.

But the same particles can also absorb light, and by absorbing light, they

become warmer, and they warm the surrounding air.

So this effect is to warm the atmosphere.

And how much light is reflected and how much is absorbed depends

on the chemical composition of the particles or their size,

even on their shape.

There's another effect that aerosols exert on climate,

because they

affect the properties of clouds,

and clouds are a major modulator of, of the amount of energy that

reaches the, the surface and warms it.

And so by changing the properties of clouds it, and precipitation,

the aerosols can

also affect climate.

The most important knowledge that we have is that aerosol particles

are extremely

complex,

so we need to study the distribution of particles globally, and the only

way to do that is from satellites.

The knowledge about aerosols that we have tells us

that the instrumentation on the

satellite must also be very complicated.

And with this instrumentation, we must be able to infer many

properties of the aerosol particles from space.

And that's the purpose of the aerosol polarimetry sensor,

which will fly as part of

the Glory mission.

We are not interested so much in their total number as how they are

distributed, because their distribution affects local

climate, and that's

why we need to know this distribution with very high accuracy.