Stray light corrections to actinic flux measurements during CONTRAST

Abstract:

Due to their configuration using a single monochromator, CCD-based actinic flux detectors have issues with stray light affecting the calibration of UV-B spectra. This in turn affects the calculation of ozone photolysis frequencies. In the summer of 2014, we flew a Scanning Actinic Flux Spectrometer (SAFS) with high stray light rejection alongside a CCD-based Actinic Flux Spectrometer (CAFS) on the NCAR C-130 for the Front Range Air Pollution and Photochemistry Experiment (FRAPPE) mission. The data from the comparison will be used to evaluate the current stray light correction techniques in our calibrations and the effects on calculated ozone photolysis. These results will be used to improve calculated photolysis frequencies during the CONvective TRansport of Active Species in the Tropics (CONTRAST) mission. We will present flux and j-value comparisons with the NCAR TUV model during high altitude, clear sky flight legs over the Pacific to demonstrate the impact of stray light corrections.