Level 0 to 1 processing of the imaging Fourier transform spectrometer GLORIA: generation of radiometrically and spectrally calibrated spectra

Abstract

Abstract. The Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA) is an imaging Fourier transform spectrometer that is capable of operating on various high-altitude research aircraft. It measures the atmospheric emission in the thermal infrared spectral region in limb and nadir geometry. GLORIA consists of a classical Michelson interferometer combined with an infrared camera. The infrared detector has a usable area of 128 × 128 pixels, measuring up to 16 384 interferograms simultaneously.Imaging Fourier transform spectrometers impose a number of challenges with respect to instrument calibration and algorithm development. The optical setup with extremely high optical throughput requires the development of new methods and algorithms for spectral and radiometric calibration. Due to the vast amount of data there is a high demand for scientifically intelligent optimisation of the data processing.This paper outlines the characterisation and processing steps required for the generation of radiometrically and spectrally calibrated spectra. Methods for performance optimisation of the processing algorithm are presented. The performance of the data processing and the quality of the calibrated spectra are demonstrated for measurements collected during the first deployments of GLORIA on aircraft.

Denitrification, dehydration and ozone loss during the 2015/2016 Arctic winter

“…The list of species with signatures in this spectral range includes temperature, H 2 O, HDO, O 3 , CH 4 , N 2 O, CFC-11, CFC-12, HCFC-12, SF 6 , HNO 3 , N 2 O 5 , ClONO 2 , HO 2 NO 2 , PAN, C 2 H 6 , H 2 CO and NH 3 . Details on the instrument design and calibration are given in Friedl-Vallon et al (2014) and Kleinert et al (2014). GLORIA is operated in a highspectral, medium-spatial sampling ("chemistry") mode and a medium-spectral, high-spatial sampling ("dynamics") mode.…”

Level 2 processing for the imaging Fourier transform spectrometer GLORIA: derivation and validation of temperature and trace gas volume mixing ratios from calibrated dynamics mode spectra

“…These processors transform the detector signals as a function of the interferometer sledge position to calibrated spectra (see Kleinert et al, 2014;Guggenmoser et al, 2014, for details). The level 2 processing by the Juelich Rapid Spectral Simulation Code V2 (JURASSIC2) and the JUelich Tomographic Inversion Library (JUTIL) software packages map the radiance values measured at different el- (Tikhonov and Arsenin, 1977).…”

Characterization of blackbody inhomogeneity and its effect on the retrieval results of the GLORIA instrument

“…Furthermore, GLORIA is able to pan the LOS from 45 to 135 • azimuth. This allows for tomographic retrievals in order to acquire 3-D images of atmospheric features Krisch et al, 2017). The ability to pan the LOS is also used to point the FTS towards the two calibration blackbodies.…”

“…4. More details on the calibration concept of GLO-RIA are given by Kleinert et al (2014) and Olschewski et al (2013).…”