Comparison and synergy of stratospheric ozone measurements by satellite limb sounders and the ground-based microwave radiometer SOMORA K. Hocke1, N. Kämpfer1, D. Ruffieux2, L. Froidevaux3, A. Parrish4, I. Boyd4, T. von Clarmann5, T. Steck5, Y. M. Timofeyev6, A. V. Polyakov6, and E. Kyrölä7 1Institute of Applied Physics, University of Bern, Switzerland 2MeteoSwiss, Payerne, Switzerland 3Jet Propulsion Laboratory, California Institute of Technology, Pasadena, USA 4University of Massachusetts, USA 5Institut für Meteorologie und Klimaforschung, Forschungszentrum Karlsruhe und Universität Karlsruhe, Germany 6Department of Atmospheric Physics, St. Petersburg State University, Russia 7Finnish Meteorological Institute, Helsinki, Finland
Abstract. Stratospheric O3 profiles obtained by the satellite limb sounders
Aura/MLS, ENVISAT/MIPAS, ENVISAT/GOMOS, SAGE-II, SAGE-III, UARS/HALOE are
compared to coincident O3 profiles of the ground-based microwave
radiometer SOMORA in Switzerland. Data from the various measurement
techniques are within 10% at altitudes below 45 km. At altitudes 45–60 km,
the relative O3 differences are within a range of 50%. Larger
deviations at upper altitudes are attributed to larger relative measurement
errors caused by lower O3 concentrations. The spatiotemporal
characteristics of the O3 differences (satellite – ground station)
are investigated by analyzing about 2300 coincident profile pairs of Aura/MLS
(retrieval version 1.5) and SOMORA. The probability density function of the
O3 differences is represented by a Gaussian normal distribution. The dependence of
the O3 differences on the horizontal distance between the sounding
volumes of Aura/MLS and SOMORA is derived. While the mean bias (Aura/MLS –
SOMORA) is constant with increasing horizontal distance (up to 800 km), the
standard deviation of the O3 differences increases from around 8 to
11% in the mid-stratosphere. Geographical maps yield azimuthal dependences
and horizontal gradients of the O3 difference field around the SOMORA
ground station. Coherent oscillations of O3 are present in the time
series of Aura/MLS and SOMORA (e.g., due to traveling planetary waves).
Ground- and space-based measurements often complement one another. We
discuss the double differencing technique which
allows both the cross-validation of two satellites by means of a ground station and
the cross-validation of distant ground stations by means of one satellite.
Temporal atmospheric noise in the geographical ozone map over Payerne is significantly
reduced by combination of the data from SOMORA and Aura/MLS. These analyses illustrate
the synergy of ground-based and space-based measurements.
Citation: Hocke, K., Kämpfer, N., Ruffieux, D., Froidevaux, L., Parrish, A., Boyd, I., von Clarmann, T., Steck, T., Timofeyev, Y. M., Polyakov, A. V., and Kyrölä, E.: Comparison and synergy of stratospheric ozone measurements by satellite limb sounders and the ground-based microwave radiometer SOMORA, Atmos. Chem. Phys., 7, 4117-4131, doi:10.5194/acp-7-4117-2007, 2007.