Validation of first chemistry mode retrieval results from the new limb-imaging FTS GLORIA with correlative MIPAS-STR observations

Abstract

Abstract. We report first chemistry mode retrieval results from the new airborne limb-imaging infrared FTS (Fourier transform spectrometer) GLORIA (Gimballed Limb Observer for Radiance Imaging of the Atmosphere) and comparisons with observations by the conventional airborne limb-scanning infrared FTS MIPAS-STR (Michelson Interferometer for Passive Atmospheric SoundingSTRatospheric aircraft). For GLORIA, the flights aboard the high-altitude research aircraft M55 Geophysica during the ESSenCe campaign (ESa Sounder Campaign 2011) were the very first in field deployment after several years of development. The simultaneous observations of GLORIA and MIPAS-STR during the flight on 16 December 2011 inside the polar vortex and under conditions of optically partially transparent polar stratospheric clouds (PSCs) provided us the first opportunity to compare the observations by two different infrared FTS generations directly. We validate the GLO-RIA results with MIPAS-STR based on the lower vertical resolution of MIPAS-STR and compare the vertical resolutions of the instruments derived from their averaging kernels. The retrieval results of temperature, HNO 3 , O 3 , H 2 O, CFC-11 and CFC-12 show reasonable agreement of GLO-RIA with MIPAS-STR and collocated in situ observations. For the horizontally binned hyperspectral limb images, the GLORIA sampling outnumbered the horizontal cross-track sampling of MIPAS-STR by up to 1 order of magnitude. Depending on the target parameter, typical vertical resolutions of 0.5 to 2.0 km were obtained for GLORIA and are typically a factor of 2 to 4 better compared to MIPAS-STR. While the improvement of the performance, characterization and data processing of GLORIA are the subject of ongoing work, the presented first results already demonstrate the considerable gain in sampling and vertical resolution achieved with GLO-RIA.

MIPAS IMK/IAA CFC-11 (CCl3F) and CFC-12 (CCl2F2) measurements: accuracy, precision and long-term stability

“…Characteristics of MIPAS-STR, the data processing and uncertainties of the retrieval results are briefly summarized in the following. Further information on MIPAS-STR is found in Keim et al (2008), Woiwode et al (2015) and references therein. MIPAS-STR em-3360 E. Eckert et al: MIPAS IMK/IAA CFC-11 and CFC-12: accuracy, precision and long-term stability ploys four liquid He-cooled detectors/channels in the spectral range between 725 and 2100 cm −1 (13.8 and 4.8µm).…”

Airborne limb-imaging measurements of temperature, HNO<sub>3</sub>, O<sub>3</sub>, ClONO<sub>2</sub>, H<sub>2</sub>O and CFC-12 during the Arctic winter 2015/2016: characterization, in situ validation and comparison to Aura/MLS

“…During these campaigns, the instrument was constantly improved , the data processing was revised Guggenmoser et al, 2015), the level 2 products were validated Woiwode et al, 2015;Ungermann et al, 2015), and GLORIA data proved to be useful for model validation (Khosrawi et al, 2017) and case studies Krisch et al, 2017). Improvements to the instrument (reduced aero-acoustic noise in the spectra) compared to the results of Woiwode et al (2015) also increase the quality of the measured infrared spectra, resulting in different characteristics of the retrieved temperature and trace gas profiles.…”

“…Lower CI values indicate a larger influence of clouds on the spectrum. In previous studies using comparable airborne limb-emission observations, typically fixed cloud index thresholds between 2 and 4 were used Woiwode et al, 2012Woiwode et al, , 2015. In this work, a CI threshold of 3 is used for the lowest and 1.8 for the highest limb tangent altitude to account also for observations moderately affected by PSCs.…”

“…Ungermann et al (2015) discussed and validated GLORIA temperature, H 2 O, HNO 3 and O 3 retrievals from the GLORIA high-spatial-resolution mode. Woiwode et al (2015) described the first GLORIA high-spectral-resolution observations captured in 2011 during the ESA Sounder Campaign (ESSenCe). They compared temperature, HNO 3 , O 3 , H 2 O, CFC-11 and CFC-12 profiles with in situ profiles and MIPAS-STR co-located profiles, and they found that GLO-RIA, at this stage of development, showed an agreement with MIPAS-STR and in situ instruments, within the profile-toprofile variations of GLORIA.…”

“…The retrieval quantity is the LOS, temperature, vmr of HNO 3 , O 3 , ClONO 2 and CFC-12 or the logarithm of vmr of H 2 O. To consider atmospheric aerosols and transparent clouds, the logarithm of an artificial continuum is part of the retrieval vector as described in Woiwode et al (2015).…”