Articles | Volume 8, issue 8
Research article
07 Aug 2015
Research article |  | 07 Aug 2015

New calibration noise suppression techniques for the GLORIA limb imager

T. Guggenmoser, J. Blank, A. Kleinert, T. Latzko, J. Ungermann, F. Friedl-Vallon, M. Höpfner, M. Kaufmann, E. Kretschmer, G. Maucher, T. Neubert, H. Oelhaf, P. Preusse, M. Riese, H. Rongen, M. K. Sha, O. Sumińska-Ebersoldt, and V. Tan

Abstract. The Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA) presents new opportunities for the retrieval of trace gases in the upper troposphere and lower stratosphere. The radiometric calibration of the measured signal is achieved using in-flight measurements of reference blackbody and upward-pointing "deep space" scenes. In this paper, we present techniques developed specifically to calibrate GLORIA data exploiting the instrument's imaging capability. The algorithms discussed here make use of the spatial correlation of parameters across GLORIA's detector pixels in order to mitigate the noise levels and artefacts in the calibration measurements. This is achieved by combining a priori and empirical knowledge about the instrument background radiation with noise-mitigating compression methods, specifically low-pass filtering and principal component analysis (PCA). In addition, a new software package for the processing of GLORIA data is introduced which allows us to generate calibrated spectra from raw measurements in a semi-automated data processing chain.

Short summary
The plane-carried Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA) measures the thermal radiation emitted by gases and particles in the atmosphere, in a height range of about 5-20 km. In between these measurements, GLORIA is pointed at known radiation sources for calibration. Noise in these calibration measurements can lead to artefacts in the final products. In this paper, we present new techniques which exploit GLORIA's imaging capabilities to reduce these noise effects.