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L i n k s

OClO is produced by the reaction of BrO and ClO it can be used as an indicator for chlorine activation of the stratosphere. Thus daily OClO maps of the polar region can provide unique information about the status of the stratospheric chemistry. In particular they might be used for the planning of stratospheric balloon launches and aircraft campaigns for the scientific community. The University of Heidelberg in co-operation with the University of Bremen developed and validated an algorithm for the detection of the atmospheric OClO absorption from GOME. The level 1 GOME data is transferred from the ESA satellite receiving station in Kiruna, Sweden to the NADIR data base at NILU (Norwegian Institute for Air Research) where the daily spectral analysis of the OClO is carried out. The produced GOME OClO maps show the so-called slant column density (SCD) of OClO for each single GOME measurement. The SCD is the integrated atmospheric OClO concentration along the light path of a GOME observation. Thus it depends strongly on the length of the light path through the atmosphere which is a function of the solar zenith  angle (SZA) at the observation site, which in turn largely depends on the latitude. Enhanced OClO absorption is generally only detected when the stratospheric temperatures inside within the polar vortex below ca. 200K. Occasionally, 'apparent' OClO absorption may appear outside of the polar vortex on the maps. This should be regarded as an artifact in the NRT analysis program. Please note: Since for GOME measurements the SZA changes with latitude, different OClO SCDs for different latitudes do not necessarily represent different degrees of chlorine activation. In addition, OClO is rapidly photolysed at increasing SZA. Thus we recommend using these maps for a qualitative indication of stratospheric chlorine activation.  

More information about the GOME OClO products can be found in the following References

Wittrock, F., A. Richter, J.P. Burrows, Validation of GOME BrO and OClO observations in the northern hemisphere, Proceedings of the European Symposium on Atmospheric Measurements from Space (ESAMS 99), Jan. 18-22, ESTEC, Noordwijk, Netherlands, WPP-161, Eur. Space Agency, Noordwijk, Netherlands, pp. 735-738, 1999.

Wagner, T., D.W. Arlander, A. Richter, M. Weber, K. Bramstedt, K.-U. Eichmann, F. Wittrock, M. Wenig, J. P. Burrows, U. Platt, Rekord-Ozonverlust im arktischen Winter 1999/2000? Satellitendaten zeigen starke stratosphärische Chloraktivierung über der Arktis, Ozonbulletin des Deutschen Wetterdienstes, 73, Februar 2000.

  Wagner, T., C. Leue, K. Pfeilsticker, and U. Platt, Monitoring of the stratospheric chlorine activation by GOME OClO measurements in the austral and boreal winters 1995 through 1999, J. Geophys. Res., 106, 4971-4986, 2001.

Wagner, T, F. Wittrock, A. Richter, M. Wenig, J.P. Burrows, and U. Platt, Continuos monitoring of the high and persistent chlorine activation during the Arctic winter 1999/2000 by the GOME instrument on ERS-2, J. Geophys. Res., 0.1029/2001JD000466, 21 September 2002.