Peggy Hannon
Advisors: Beate Liepert, Steve Chillrud

Aerosols are small particles in the atmosphere, which come from a variety of natural and anthropogenic sources. They affect the climate by scattering and absorbing sunlight, affecting the energy balance at the surface of the earth and by serving as a surface for water droplets to form on, creating clouds. An abundance of aerosols in the air causes clouds to stay in the atmosphere longer, as many smaller droplets form instead of large droplets that rain out. Aerosol Optical Thickness (AOT) refers to the transparency of the atmosphere and how much light from the sun is absorbed or reflected by particles on the light’s path to the earth.
We took preliminary measurements of the AOT at LDEO (forested) and from Piermont Pier (near river water) during the months of May-July which show that there is little patterned variability, despite landscape differences (that would produce different particles). Instead, wind carries particles from a variety of sources from various distances to surrounding areas. For this reason, we conduct a feasibility study where we travel with the air mass in a hot air balloon, to see how far up aerosols exist and to determine how far they can spread. We use MetOne particle counters to determine the amount of particles in different size ranges and a Microtops Sunphotometer to measure the AOT.
We find that on a hazy day, the AOT and particle counts are much higher, as expected. On a clear day (shown below), satellite data is accurate for the AOT, as the majority of the aerosols in the air contributing to the AOT are further away, and there is little variability in the vertical direction. The particles drop off to zero around 1400 meters. However, on a hazy day, the local particles affected the AOT much more. Traveling up a well-mixed layer, the AOT dropped, as the amount of particles in the path between us and the sun lessened.