Stratospheric ozone profiles over Switzerland measured by SOMORA, ozonesonde and MLS/AURA satellite

Since January 2000, continuous information on the vertical distribution of ozone over Payerne in Switzerland has been derived from measurements taken by the stratospheric ozone monitoring radiometer SOMORA. A new retrieval of ozone profiles from the measured ozone line spectra has been developed using the inversion software ARTS/Qpack. To validate the new retrieval method it has been compared to ozone profiles measured by ozonesonde and satellite (MLS/AURA). Before May 2001 and after June 2005, the relative difference to ozonesonde is within -5 to 15% depending on the altitude. However, SOMORA and ozonesonde profiles show a difference of up to 30% below 23 km between May 2001 and June 2005, after technical interventions on the instrument, i.e. mixer and front end changes. The new retrieval still has some problems with the instrumental change of 2001 below 23 km but is satisfactory for the change of 2005 where the difference to ozonesonde has been significantly reduced compared to the previous retrieval algorithm. A high difference is shown in summer 2006 which can be related to low tropospheric transmittance during this period. The comparison to MLS on AURA satellite is good before May 2007 with values of -5 to 15% depending on the altitude. The relative difference to satellite ozone profiles show a seasonal cycle with higher values in summer correlated to low tropospheric transmittance.