The calibration of instruments for atmospheric ozone measurement with a sealed ozone cell: The OSIRIN/ODIN spectrograph Original Research Article

A new technique for the calibration of satellite instruments for atmospheric ozone measurements with a sealed ozone cell is described. Spectral measurements of the ozone absorption from a sealed gas cell are measured with a FTIR to determine the amount of ozone in the cell. The satellite instrument then views the cell against a diffuse-reflecting screen illuminated by the appropriate visible or UV source. The calibration results from the OSIRIS/ODIN spectrograph are used to demonstrate that the method works successfully. Spectral measurements of the ozone absorption from a gas cell were measured with an FTIR spectrometer to determine the amount of ozone in the cell and then used to test the performance of the OSIRIS-DM spectrograph. The ozone spectra of the Huggins and Chappuis bands that were derived from the OSIRIS measurements were found to be in good agreement with the simulated spectra of known amounts of ozone from a radiative transfer model. The measurements reported here were taken for the purpose of characterising the performance of the OSIRIS instrument at Ottawa before flight. Final measurements were also taken at Toulouse before flight in August 2000 for the purpose of calibrating the OSIRIS FM instrument. It is recommended that all future satellite instruments for measuring ozone be calibrated pre-flight using this or a similar technique. It is also recommended that all ground based ozone-monitoring instruments such as Brewer or Dobson spectrophotometers to be used for validation of satellite instruments be calibrated using this portable and inexpensive technique.