Instrument: Composition and Photodissociative Flux Measurement (CPFM)

Principal Investigator: C. Thomas McElroy

Organization:
Atmospheric Environment Service, Environment Canada
4905 Dufferin Street
Downsview, Ontario
CANADA M4K lL9

Co-Investigators: John C. McConnell, Michael J. Prather

Principle of Operation:

The instrument used for the CPFM is a spectroradiometer based on a concave, holographic diffraction grating and a 1024-element diode array detector. It measures the intensities of the two linear polarization components of radiation propagating upward at the aircraft location from a range of elevation angles near the horizon. In addition, a measurement of the intensity of the direct solar beam is made by viewing a horizontal diffusing surface mounted under a quartz dome on board the aircraft. These measurements are used to verify atmospheric light-scattering calculations, which are essential for the accurate modeling of the chemistry of the stratosphere where POLARIS makes its measurements. Observations of the total column amount of ozone above flight level will also be made. 



Free Spectral Range: 300 to 400 nm and 400 to 800 nm
         Resolution: 1.2 nm
           Accuracy: 5% plus precision
          Precision: Up to 0.03% depending on light levels

Reference:

McElroy, C.T. , L. J. B. McArthur, J. B. Kerr, D. I. Wardle, D. Tarasick, and C. Midwinter, SPEAM-II Experiment for the measurement of stratospheric NO2 ozone and NO3, Proceedings of the Quadrennial Ozone Symposium, Charlottesville, Virginia, June, 1992, in press.