AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
A Broadband Cavity-Enhanced Spectrometer for UV-Vis Extinction
MICHAEL POGASH, Al Fischer, Geoffrey Smith, The University of Georgia
Abstract Number: 623 Working Group: Instrumentation and Methods
Abstract Aerosols predominately scatter light, offsetting the warming effects caused by greenhouse gases. They have a direct radiative forcing that may be second to only CO2, but the magnitude is not well known. Uncertainties in aerosol radiative forcing propagate into climate models and prevent precise predictions. Broadband cavity-enhanced spectroscopy (BBCES) is a technique that can provide extinction measurements with high sensitivity and large wavelength coverage. With mirrors near 99.99 % reflective, cavity-enhancement allows path lengths on the order of kilometers to be achieved in a portable instrument. There have been a few, recent measurements of aerosols using BBCES, but they only cover discrete regions of the solar spectrum. We have constructed a three-channel broadband cavity-enhanced spectrometer that measures from 385 - 435, 512 - 552, and 640 - 680 nm. With a limit of detection near 1 Mm-1, extinction by ambient aerosols can be measured in their natural, suspended state and with great temporal resolution. The instrument design and recent measurements will be presented.