Stefan Versick

Publications (9) View all

• Article: Retrieval of temperature, H₂O, O₃, HNO₃, CH₄, N₂O, ClONO₂ and ClO from MIPAS reduced resolution nominal mode limb emission measurements

  T. von Clarmann, Höpfner M, Kellmann S, Linden A, Chauhan S, Funke B, Grabowski U, Glatthor N, Kiefer M, Schieferdecker T, G. P. Stiller, Versick S
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  ABSTRACT: Retrievals of temperature, H₂O, O₃, HNO₃, CH₄, N₂O, ClONO₂ and ClO from MIPAS reduced spectral resolution nominal mode limb emission measurements outperform retrievals from respective full spectral resolution measurements both in terms of altitude resolution and precision. The estimated precision (including measurement noise and propagation of uncertain parameters randomly varying in the time domain) and altitude resolution are typically 0.5–1.4 K and 2–3.5 km for temperature between 10 and 50 km altitude, and 5–6%, 2–4 km for H₂O below 30 km altitude, 4–5%, 2.5–4.5 km for O₃ between 15 and 40 km altitude, 3–8%, 3–5 km for HNO₃ between 10 and 35 km altitude, 5–8%, 2–3 km for CH₄ between 15 and 35 km altitude, 5–10%, 3 km for N₂O between 15 and 35 km altitude, 8–14%, 2.5–9 km for ClONO₂ below 40 km, and larger than 35%, 3–7 km for ClO in the lower stratosphere. As for the full spectral resolution measurements, the reduced spectral resolution nominal mode horizontal sampling (410 km) is coarser than the horizontal smoothing (often below 400 km), depending on species, altitude and number of tangent altitudes actually used for the retrieval. Thus, aliasing might be an issue even in the along-track domain. In order to prevent failure of convergence, it was found to be essential to consider horizontal temperature gradients during the retrieval.
  Atmospheric Measurement Techniques. 01/2009;
• Article: Composition changes after the "Halloween" solar proton event: the High Energy Particle Precipitation in the Atmosphere (HEPPA) model versus MIPAS data intercomparison study

  B. Funke, A. Baumgaertner, M. Calisto, T. Egorova, C. H. Jackman, J. Kieser, A. Krivolutsky, M. López-Puertas, D. R. Marsh, T. Reddmann, E. Rozanov, S. -M. Salmi, M. Sinnhuber, G. P. Stiller, P. T. Verronen, S. Versick, T. Clarmann von, T. Y. Vyushkova, N. Wieters, J. M. Wissing
  Atmos. Chem. Phys. 01/2011; 11(17):9089-9139.
• Source

  Available from: atmos-chem-phys.net

  Article: Northern Hemisphere atmospheric influence of the solar proton events and ground level enhancement in January 2005

  C. H. Jackman, D. R. Marsh, F. M. Vitt, R. G. Roble, C. E. Randall, P. F. Bernath, B. Funke, M. López-Puertas, S. Versick, G. P. Stiller, A. J. Tylka, E. L. Fleming
  Atmos. Chem. Phys. 01/2011; 11:6153-6166.
• Article: Modeling disturbed stratospheric chemistry during solar-induced NOx enhancements observed with MIPAS/ENVISAT

  T. Reddmann, R. Ruhnke, S. Versick, W. Kouker
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  ABSTRACT: Energetic particle precipitation during solar active periods induces enhancements of NOx (N, NO, NO2) in the lower thermosphere/mesosphere which can be transported to the stratosphere within the polar vortex. The quantitative contribution of these NOx intrusions to ozone chemistry in the stratosphere is still under discussion. Here we present simulations with a three-dimensional model of the middle atmosphere where NOx enhancements in the lower mesosphere have been taken from the observations of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) instrument on the European Space Agency satellite ENVISAT. Covering the period from July 2002 to March 2004 these observations include the strong solar proton event in fall 2003 and intrusions connected to auroral events during the Arctic and Antarctic winters. The comparison of the disturbed run with the undisturbed model run allows a quantitative assessment of the long-term influence of NOx intrusions on stratospheric chemistry in general and the ozone concentration in particular. From the model simulation, we estimate for the period from July 2002 to March 2004 that in total, an additional 5.4 Gigamol NOy has been brought into the middle atmosphere. This represents in early 2004 about 5% of the global NOy mass in the middle atmosphere. A 2 year decay time for such enhancements is estimated from the model. Persistent reduction of ozone concentration in the stratosphere caused by the NOx intrusions can be followed in the simulation for several months. This reduction is restricted to high latitudes and amounts to several Dobson units in the total ozone column.
  JOURNAL OF GEOPHYSICAL RESEARCH. 01/2010; 115.
• Article: Relationship of visibility, aerosol optical thickness and aerosol size distribution in an ageing air mass over South-West Germany

  D. Bäumer, B. Vogel, S. Versick, R. Rinke, O. Möhler, M. Schnaiter
  Atmospheric Environment. 01/2008; 42(5):989 - 998.