NO₂ Profile Retrieval using airborne multi axis UV-visible skylight absorption measurements over central Europe

M. Bruns (1) , S. A. Buehler (1) , J. P. Burrows (1) , A. Richter (1) , A. Rozanov (1) , P. Wang (1) , K.-P. Heue (2) , U. Platt (2) , I. Pundt (2) , T. Wagner (2)

1 IUP - Institute of Environmental Physics [Bremen]
2 IUP - Institute of Environmental Physics [Heidelberg]

A recent development in ground-based remote sensing of atmospheric constituents by UV/visible absorption measurements of scattered light is the simultaneous use of several directions with small elevation angles in addition to the traditional zenith-sky pointing. The different light paths through the atmosphere enable the vertical distribution of some atmospheric absorbers such as NO₂, BrO or O₃ to be retrieved.

In this study, the amount of profile information that can be retrieved from such measurements on aircraft is investigated for the trace gas NO₂. A Sensitivity study on synthetic data is performed for a combination of four lines of sight (LOS) (0° (nadir), 88°, 92°, and 180° (zenith)) and three wavelength regions [center wavelengths: 362.5 nm, 437.5 nm, and 485.0 nm]. This investigation demonstrates the potential of this LOS/wavelengths setup to retrieve a significant amount of profile information from airborne multiaxis differential optical absorption spectrometer (AMAXDOAS) measurements with a vertical resolution of 3.0 to 4.5 km in the lower troposphere and 2.0 to 3.5 km near flight altitude. Above 13 km the profile information content of AMAXDOAS measurements is sparse.

Further, retrieved profiles with a significant amount (up to 3.2 ppbv) of NO₂ in the boundary layer over the Po-valley (Italy) are presented. Airborne multiaxis measurements are thus a promising tool for atmospheric studies in the troposphere.

Domaines: Océan, Atmosphère

M. Bruns, S. A. Buehler, J. P. Burrows, A. Richter, A. Rozanov, et al.. NO₂ Profile Retrieval using airborne multi axis UV-visible skylight absorption measurements over central Europe. Atmospheric Chemistry and Physics Discussions, 2006, 6 (1), pp.493-517. ⟨hal-00300937⟩