Abstract
Abstract. A new "Bayesian" minimization algorithm for the retrieval of the diurnal variation of UV/vis absorbing radicals (O3, NO2, BrO, OClO and HONO) from balloon-borne limb scattered skylight observations is discussed. The method evaluates spectroscopic measurements in combination with radiative transfer calculations to drive a mathematical inversion on a discrete time and height grid. Here, the proposed method is applied to data obtained during two deployments of the mini-DOAS instrument on different balloon payloads in northern Brazil in June 2005. The retrieval is tested by comparing the inferred profiles to in-situ ozone sounding data and to measurements of the ENVISAT/SCIAMACHY satellite instrument performed during a collocated overpass. The comparison demonstrates the strength and validity of our approach. In particular for time-varying radical concentrations, photochemical corrections due to temporal mismatch of the corresponding observations are rendered dispensable. Thus, limb scanning UV/vis spectrometry from balloon platforms offers a more direct and concise approach for satellite validation of radical measurements than solar occultation measurements. Furthermore, monitoring of the diurnal variation of stratospheric radicals allows us to constrain photochemical parameters which are critical for stratospheric ozone chemistry, such as the photolysis frequency of N2O5 by observations of the diurnal variation of NO2.
Highlights
In the past decade balloon-borne remote sensing evolved into a powerful tool for the investigation of atmospheric parameters and photochemical processes relevant for stratospheric ozone chemistry
The measurement geometry is characterized by the elevation angle of the telescope (EA), the relative azimuth angle between telescope and the sun (SRAA) and the solar zenith angle (SZA)
The telescope is oriented to the horizon at a fixed EA during balloon ascent when the gondola ascends through the atmosphere, providing a large sensitivity for trace gases at the particular tangent height
Summary
In the past decade balloon-borne remote sensing evolved into a powerful tool for the investigation of atmospheric parameters and photochemical processes relevant for stratospheric ozone chemistry These spectroscopic techniques have been developed to remotely detect a wide range of stratospheric trace gases via their spectral signatures. Among a larger series of stratospheric balloon flights (see Table 1), favorable conditions for long duration observations, which are necessary to study the diurnal variation of radicals, were only met a limited number of times Those flights were performed from the tropical station Teresina, Brazil (5.1◦ S, 42.9◦ W) in 2005 and 2008, or in high-latitude summer 2002 (Kiruna, Sweden, 67.9◦ N, 22.1◦ E) during turn-over of the stratospheric circulation.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
