Effects of spectral resolution and signal-to-noise ratio of hyperspectral sensors on retrieving atmospheric parameters.

Space-borne Fourier Transform Infrared (FTIR) spectroscopy has been operationalized to obtain atmospheric parameters. The spectral resolution and signal-to-noise ratio (SNR) of FTIR spectroscopy are its two key parameters. Given fixed costs and technical limitations, one has to choose between less information (low spectral resolution) and low noise (high SNR), or high information and high noise. This study illustrates one important, although not well realized fact: Downgrading from a high to a low spectral resolution measurement cannot achieve the same SNR as the latter. By comparing the Infrared Atmospheric Sounding Interferometer (IASI) and the Cross-track Infrared Sounder (CrIS) data at operational mode (low spectral resolution) and at experimental high spectral resolution, it is found that full CrIS resolution is required to accurately detect trace gases in the atmosphere. This study investigated three approaches for spectral data reduction, and compared their effects on the retrieval of atmospheric parameters.