Spectral interpolation for satellite high-resolution spectral measurements
Abstract
Nowadays, the satellite-based high resolution spectral measurement has become an indispensable tool to probe the Earth atmosphere including its gas composition. As a few examples we can point out on the ill-fortune OCO, highly successful GOSAT, or SCIAMACHY satellite missions. Despite quite an impressive spectral resolution of their spectrometers (0.2-0.4 cm-1) only a few points per a spectral line are measured and the position of this points are not constant because of the satellite and Sun movement with respect of an observational point which makes it even more difficult to employ any method requiring to perform interpolation to a predetermined grid since application of standard interpolation techniques frequently results in unacceptably large errors (Roscoe el al, Appl.Opt 35, 427). In addition to the spectral shift due to the Doppler effect undersampling in high resolution spectral measurements has been recently recognized and attempt based on using a convolved reference solar spectrum has been made (Chance el al, Appl.Opt 44, 1296). This technique being useful at instrument resolution of 6 cm-1 seems hardly to result in success at 20 times higher resolution typical for the GOSAT or OCO missions since variation in measured spectrum is mostly determined by the gas absorption. Quite often the processing of the remote sensing assumes that the probed atmosphere has a optically thin scattering component (aerosols or clouds). This allows us to use a simplified description of photon propagation in the atmosphere to generate more physical approach for interpolation based on the known atmospheric gas spectroscopy allowing us to generate a non orthogonal set of functions to perform interpolation. This method allows achieving an accurate interpolation with error level below the noise level when the standard techniques fail (see the figure).
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFM.A33C0211P
- Keywords:
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- 0360 ATMOSPHERIC COMPOSITION AND STRUCTURE / Radiation: transmission and scattering;
- 0394 ATMOSPHERIC COMPOSITION AND STRUCTURE / Instruments and techniques