Start
March 17, 2021 - 2:00 pm
End
March 17, 2021 - 3:00 pm
Categories
Weather and Climate SystemsWeather and Climate Systems Seminar
Extending 4STAR Measurements and Retrievals
from the 2016 ORACLES Campaign
Logan Mitchell
Wednesday, March 17th
2:00 pm
Join Google Meet:
https://meet.google.com/jdv-kpfr-gnu
Aerosols play a complex role in Earth systems, cooling in certain contexts and warming in others, such that their radiative forcing remains a persistent climate modeling uncertainty. These uncertainties continue due to the disparity between readily observed aerosol properties and the components of climate models. For example, although accurate Aerosol Optical Depth (AOD) measurements are broadly available, the observed AOD is typically the sum of several contributing factors and thus it is difficult for the models to gauge their accuracy against this value alone.
Fortunately, the complicated nature of aerosols may also provide a means for studying its speciation. Aerosols are capable of both scattering and absorbing light. Absorbing aerosols are of three main types: Black Carbon (BC), Brown Carbon (BrC), and mineral dust. The absorption of each of these aerosol types exhibits distinct spectral characteristics.
AERONET, a global network of ground-based sun/sky photometers, retrieves aerosol properties from measurements of direct sun and cloud-free sky, typically at four wavelengths. The NASA 4STAR spectrophotometer operates like an airborne AERONET system with advanced hyperspectral capabilities providing hundreds of channels extending into the UV range. Published comparisons from the NASA ORACLES 2016 campaign demonstrate robust AERONET-like retrievals from 4STAR airborne measurements, but some limitations remain. This includes a limitation on arbitrary wavelength selection, an instrument artifact near 425nm, AOD fitting routine limitations, and stray light scattering in the shorter wavelengths. We are optimistic that these limitations can be addressed and overcome, allowing for an optimal wavelength selection and accurate retrieval processing.