A static Fourier transform spectrometer for atmospheric sounding: concept and experimental implementation

Area of Science:

• Earth and Space Science
• Atmospheric Science
• Spectroscopy

Background:

• Spaceborne remote sensing is crucial for monitoring atmospheric composition.
• Accurate measurement of atmospheric carbon dioxide (CO2) is vital for estimating surface fluxes.
• Absorption spectroscopy at 1.6 and 2.0 microns is a promising technique for CO2 detection.

Purpose of the Study:

• To introduce a novel, compact spectrometer concept for microsatellite platforms.
• To enable high-resolution spaceborne monitoring of carbon dioxide absorption lines.
• To improve the accuracy and information content of atmospheric CO2 measurements.

Main Methods:

• Development of a Fourier Transform Spectrometer (FTS) concept using stepped mirrors instead of a classical moving mirror.
• Imaging the interferogram onto a CCD matrix for data acquisition.
• Incorporation of a modulating plate to control path difference and enhance measurements.

Main Results:

• Achieved a high resolving power of approximately 65,000 in laboratory models.
• Demonstrated a signal-to-noise ratio of around 300 for the spectral data.
• Validated the instrument's suitability for observing specific CO2 absorption lines within narrow spectral bands.

Conclusions:

• The developed compact FTS concept is well-suited for spaceborne atmospheric CO2 monitoring.
• This technology offers a significant advancement for estimating surface CO2 fluxes.
• The instrument provides high-resolution spectral data with excellent signal-to-noise, improving measurement information content.