Method and results for optimizing the MOPITT methane bandpass

The Measurements of Pollution in the Troposphere (MOPITT) instrument will measure carbon monoxide and total column methane in the Earth's atmosphere by means of gas-filter correlation radiometry. The center, width, and shape of the bandpass filters used to isolate the spectral channels must maximize the signal level and sensitivity to the gas of interest and minimize the interference from other absorbing gases (notably water vapor). I calculated the sensitivity to methane and the interference from other gases as a function of filter center and width. A slight shift in the filter parameters from the MOPITT baseline values increases the methane sensitivity by 20% and decreases the water vapor interference to 6% of its baseline value.