Ozone Climatology obtained by a combination of MLS/AURA and SHADOZ ozonesondes profiles over southern tropic and subtropic

Abstract : In this paper a new ozone climatology (1998-2012) is presented over 8 southern tropic and subtropic sites. The climatology has been formed by combining data from Aura –MLS (Microwave Limb Sounder) and from SHADOZ (Southern Hemisphere ADditional OZonesondes) balloon sonde. Prior to combine the two observations, a preliminary study has been conducted to validate MLS profiles by comparison with ozonesondes. A satisfactory agreement is observed between MLS and ozonesonde measurements especially from 20 km to 30 km where the monthly relative difference between the two observations with respect to ozonesonde measurement is between 0.36% and 9.30%. The bias between the two observations decreases with the increase of altitude; from 20 km to 30 km the observed mean bias is assessed to be 3.69±1.13% with respect to SHADOZ observations. The presented climatology consists of monthly averages of ozone profiles for each site obtained from 1 km to 62 km. This climatology is established from hybrid profiles, normalized with the corresponding total column ozone (TCO) measured by Aura Ozone Monitoring Instrument, OMI satellite. Ozone below 26 km is based on ozonesonde while ozone above 29 km is based on MLS measurements. SHADOZ and MLS profiles are merged between 26 and 29 km where the best agreement (around 1%) between SHADOZ and MLS is observed. The obtained climatology captures with more accurately the principle behavior of ozone seasonal and spatial distributions; the integrated total ozone amounts from the presented climatology are consistent with the measured TCO from SAOZ (Système d'Analyse par Observation Zénitale) and Dobson at Reunion and Irene respectively.