Retrieval of stratospheric O₃, HNO₃ and ClONO₂ profiles from 1992 MIPAS‐B limb emission spectra: Method, results, and error analysis

Abstract

Within the framework of the European Arctic Stratospheric Ozone Experiment, two flights of the balloon-borne MIPAS-B limb emission spectrometer were performed in the Arctic stratosphere from Kiruna, northern Sweden. During the early hours of January 13 and the night from March 14 to March 15, 1992, several limb sequences of infrared spectra were recorded which have permitted the retrieval of vertical profiles of many trace gases relevant for ozone chemistry. In the present work, the retrieval strategy, error estimation strategy, and resulting profiles of 03, HNO3, and C1ONO2 are reported. The data analysis procedure, consisting of data preprocessing including calibration, analysis of auxiliary data including temperature profiles and line of sight determination, and retrieval of trace gas profiles, is described in detail. The last is carried out by means of multiparameter nonlinear least squares fitting in combination with onion peeling. An astonishingly high C1ONO2 amount of 2.6 ppb by volume at about 19-km altitude was inferred for the March flight. A rigorous error analysis, which takes into account systematic and random errors and their often nonlinear impact on the results, proves the significance of the retrieved trace gas profiles. mary of previous campaigns are published elsewhere [Oelhaf et al., 1991; Friedl-Vallon et al., 1992]. Two flights were performed by the Centre National d'Etudes Spatiales in cooperation with the Swedish Space Corporation from Esrange near Kiruna, northern Sweden (68øN, 21øE) within the framework of the European Arctic Stratospheric Ozone Experiment (EASOE) in 1992. For details of the 1992 campaign and a discussion of the results in the meteorological and scientific context of EASOE, see Oelhaf et al. [1993].The first flight took place in the early hours of January 13. The balloon remained nearly stationary above the Gulf of Bothnia, inside the polar vortex. From an average floating altitude of 31 km, limb emission spectra were recorded at elevation angles from -4.7 ø to + 2.6 ø, corresponding to tangent altitudes down to 9 km. Spectra of tangent altitudes of 13 km and higher have been used for trace gas retrievals so far. Because of a malfunction of the azimuth stabilization system, spectra of many different azimuth directions were recorded. They were classified into three main azimuth groups (northwest, northeast, southeast) to be analyzed separately.The second flight, on March 14,/15, was characterized by a trajectory north of the edge of the polar vortex and ended with a crash landing near Nikel, northwest of Murmansk, Russia. From an average floating altitude of about 33 kin, two complete sequences of spectra were recorded. Looking northeast, spectra were measured under elevation angles down to -5.1 ø, corresponding to a lowest tangent altitude of 6 km. Spectra of tangent altitudes of 11.3 km and higher have been used for trace gas retrievals so far. Looking south, spectra related to air of the vortex edge region were recorded at elevation angles from -4.9 ø to -1.5 ø, corres...

First remote sensing measurements of ClOOCl along with ClO and ClONO<sub>2</sub> in activated and deactivated Arctic vortex conditions using new ClOOCl IR absorption cross sections

“…Polar winter vertical profiles of ClONO 2 have been inferred from limb emission spectra measured by the balloon version of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS-B) for many years (see, e.g., von Clarmann et al, 1993Clarmann et al, , 1997Oelhaf et al, 1994;Stowasser et al, 2002;Wetzel et al, 2002Wetzel et al, , 2006. The high quality of the MIPAS-B ClONO 2 observations has been proven by comparisons to data of other instruments such as MIPAS on board the environmental satellite ENVISAT and the first and second Improved Limb Atmospheric Spectrometer (ILAS) sensors Wetzel et al, 2008) aboard the Japanese ADEOS satellites.…”

Optical and microphysical parameters of the Mt. Pinatubo aerosol as determined from MIPAS‐B mid‐IR limb emission spectra

“…In each of the microwindows the vertical profile of the aerosol pseudo-extinction coei•icient has been retrieved by onion peeling in combi• nation with a least squares fitting approach. The retrievals were performed by the retrieval software package RAT [von Clarmann, 1994] The aerosol pseudo-extinction coefficients, as retrieved from the MIPAS-B spectra in the lowest three tangent altitudes, are shown in Figure 3 as Stratospheric aerosol particles at temperatures considerably higher than the frost point of sulfuric acid tetrahydrate (SAT) are composed of liquid droplets that can be assumed to be spherical [Tolbert, 1994] From the spectral pseudo-extinction coefficients, retrieved at approximately 60 spectral points in the MI-PAS spectral range, the composition and the parameters of the lognormal size distribution can be retrieved. For sulfuric acid aerosols, spectral reftactive indices for the infrared spectral region are tabulated for six different weight percentages of H2SO4 between 25% and 95.6% [Palmer and Williams, 1975] …”

Validation of MIPAS ClONO<sub>2</sub> measurements

“…Regularly, during Arctic and Antarctic winter heterogeneous chlorine activation takes place at polar stratospheric cloud (PSC) particles which is a prerequisite for the fast catalytic destruction of ozone in springtime. In the Arctic polar vortex the recovery of chlorine into the reservoir gases predominantly takes place via reaction (1) leading to large concentrations of ClONO 2 in the lower stratosphere (von Clarmann et al, 1993;Oelhaf et al, 1994). However, under conditions of strong ozone depletion, which is usually the case in the springtime Antarctic lower stratosphere, active chlorine is primarily converted into HCl (Douglass et al, 1995;Mickley et al, 1997;Grooss et al, 1997;Michelsen et al, 1999):…”

“…Examples for sun-independent determination of ClONO 2 through mid-IR thermal emission spectroscopy are balloonborne measurements by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS-B) (von Clarmann et al, 1993;Oelhaf et al, 1994), airborne observation by MIPAS-FT (Blom et al, 1995), and spaceborne measurements by the Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere (CRISTA) (Riese et al, 2000) and by the Cryogenic Limb Array Etalon Spectrometer (CLAES) (Roche et al, , 1994. CLAES obtained nearly global fields of ClONO 2 from 25 October 1991 until 5 May 1993 which have been validated by Mergenthaler et al (1996).…”