Inter-comparison of stratospheric O<sub>3</sub> and NO<sub>2</sub> abundances retrieved from balloon borne direct sun observations and Envisat/SCIAMACHY limb measurements

Abstract

Abstract. Stratospheric O 3 and NO 2 abundances measured by different remote sensing instruments are intercompared: (1) Line-of-sight absorptions and vertical profiles inferred from solar spectra in the ultra-violet (UV), visible and infrared (IR) wavelength ranges measured by the LPMA/DOAS (Limb Profile Monitor of the Atmosphere/Differential Optical Absorption Spectroscopy) balloon payload during balloon ascent/descent and solar occultation are examined with respect to internal consistency. (2) The balloon borne stratospheric profiles of O 3 and NO 2 are compared to collocated space-borne skylight limb observations of the Envisat/SCIAMACHY satellite instrument. The trace gas profiles are retrieved from SCIAMACHY spectra using different algorithms developed at the Universities of Bremen and Heidelberg and at the Harvard-Smithsonian Center for Astrophysics. A comparison scheme is used that accounts for the spatial and temporal mismatch as well as differing photochemical conditions between the balloon and satellite borne measurements. It is found that the balloon borne measurements internally agree to within ±10% and ±20% for O 3 and NO 2 , respectively, whereas the agreement with the satellite is ±20% for both gases in the 20 km to 30 km altitude range and in general worse below 20 km.

Balloon-borne stratospheric BrO measurements: comparison with Envisat/SCIAMACHY BrO limb profiles

“…Thus, apart from unknown instrumental problems, the discrepancy between modelled and measured BrO cannot be explained. The time lag for the backward match between the satellite and the balloon measurement is quite short (−2.5 h) and match criteria are fulfilled between 16 and 33 km (see Table 1 Butz et al (2005). The SZAs of the SCIAMACHY backward and forward match are 81.2 • and 57.7 • , respectively.…”

“…For the TRIPLE BrO observation such a scaling of modelled/measured NO 2 is more difficult since the NO 2 is not measured on that payload. Therefore, SCIAMACHY NO 2 observations (Sioris et al, 2004) are used, which were validated by balloon measurements by Butz et al (2005). Further photochemistry-related uncertainties in the SAOZ and DOAS observations are kept small when only using measurements for SZA≤88 • , i.e.…”

“…In the case of DOAS measurements the scaling is performed prior to profile inversion as described by Butz et al (2005), thus compensating photochemical changes during the ascent measurements of the balloon. For TRIPLE and SAOZ measurements, the ratio of the model profile at the SZA of the satellite measurement and the model profile at the SZA of the balloon measurement is calculated, and used to scale the profiles accordingly.…”

“…Profile information on stratospheric BrO was obtained by a least-squares profile inversion technique (Maximum A Posteriori) (Rodgers, 2000). A more detailed description of the DOAS profile inversion can be found in Butz et al (2005 To better estimate the error propagation in the BrO profile, inversion is performed twice. First the BrO SCDs are inverted with the errors as given by the fitting routine.…”

The use of NO<sub>2</sub> absorption cross section temperature sensitivity to derive NO<sub>2</sub> profile temperature and stratospheric–tropospheric column partitioning from visible direct-sun DOAS measurements

“…Vertical stratospheric NO 2 profiles during sunset/sunrise were derived from zenith sky (e.g., McKenzie et al, 1991;Preston et al, 1997;Hendrick et al, 2004) and balloon DOAS measurements (e.g., Pommereau and Piquard, 1994;Butz et al, 2006;Kritten et al, 2010). Sunset and sunrise stratospheric NO 2 columns have been measured since 1991 at multiple locations throughout the world as part of the international Network for the Detection of Atmospheric Composition Change (NDACC) .…”