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

Abstract

Abstract. The Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA) is an airborne infrared limb imager combining a two-dimensional infrared detector with a Fourier transform spectrometer. It was operated aboard the new German Gulfstream G550 High Altitude LOng Range (HALO) research aircraft during the Transport And Composition in the upper Troposphere/lowermost Stratosphere (TACTS) and Earth System Model Validation (ESMVAL) campaigns in summer 2012. This paper describes the retrieval of temperature and trace gas (H 2 O, O 3 , HNO 3 ) volume mixing ratios from GLORIA dynamics mode spectra that are spectrally sampled every 0.625 cm −1 . A total of 26 integrated spectral windows are employed in a joint fit to retrieve seven targets using consecutively a fast and an accurate tabulated radiative transfer model. Typical diagnostic quantities are provided including effects of uncertainties in the calibration and horizontal resolution along the line of sight. Simultaneous in situ observations by the Basic Halo Measurement and Sensor System (BAHAMAS), the Fast In-situ Stratospheric Hygrometer (FISH), an ozone detector named Fairo, and the Atmospheric chemical Ionization Mass Spectrometer (AIMS) allow a validation of retrieved values for three flights in the upper troposphere/lowermost stratosphere region spanning polar and sub-tropical latitudes. A high correlation is achieved between the remote sensing and the in situ trace gas data, and discrepancies can to a large extent be attributed to differences in the probed air masses caused by different sampling characteristics of the instruments.This 1-D processing of GLORIA dynamics mode spectra provides the basis for future tomographic inversions from circular and linear flight paths to better understand selected dynamical processes of the upper troposphere and lowermost stratosphere.

Transport of Antarctic stratospheric strongly dehydrated air into the troposphere observed during the HALO-ESMVal campaign 2012

“…The water vapor precision and total error (accuracy + precision) amounts to about 0.2 and 1.0 ppmv in the stratosphere. Ungermann et al (2015) showed that GLO-RIA water vapor at flight level agrees fairly well with the in situ FISH measurements, within error bars. The deviations to FISH during the ESMVal/TACTS flights are mostly less than 0.4 ppmv.…”

“…Downward transport could be either very fast along tilted isentropes on timescales of 1-5 days (Škerlak et al, 2014) or slower by radiative cooling and reduction in potential temperature. In the latter case, air masses can potentially descend from the thermal tropopause to near-surface heights within 10 days (descent rate of 5 mm s −1 ) or longer as reported by van de Berg et al (2007). Rossby wave-induced stratospheric intrusions, such as tropopause folds, occur more often further north and in the midlatitudes than directly above the Antarctic continent (Sprenger et al, 2003;Škerlak et al, 2014).…”

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

“…Due to the higher spatial sampling along the flight track, a larger set of profiles is measured. 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).…”

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

“…Typical noise values of the GLORIA instrument are added to these spectra. These synthetic measurements are transferred back into the geophysical quantities of temperature and trace gas volume mixing ratios according to the retrieval setup described in Ungermann et al (2015) for the GLORIA dynamics mode. A gain matrix G is calculated in this retrieval process, which correlates measurement deviations ( L) with retrieval result uncertainties ( x).…”

“…This flight took place on 26 February 2016. The retrieval setup used is described by Ungermann et al (2015). We focus here solely on the climate-relevant variables of temperature, water vapor, and ozone.…”