Abstract
Abstract. We have created a daytime ozone profile data set from the measurements of the Global Ozone Monitoring by Occultation of Stars (GOMOS) instrument on board the Envisat satellite. This so-called GOMOS bright limb (GBL) data set contains ∼ 358 000 stratospheric daytime ozone profiles measured by GOMOS in 2002–2012. The GBL data set complements the widely used GOMOS nighttime data based on stellar occultation measurements. The GBL data set is based on the GOMOS daytime occultations but instead of the transmitted star light we use limb-scattered solar light. The ozone profiles retrieved from these radiance spectra cover the 18–60 km altitude range and have approximately 2–3 km vertical resolution. We show that these profiles are generally in better than 10 % agreement with the NDACC (Network for the Detection of Atmospheric Composition Change) ozonesonde profiles and with the GOMOS nighttime, MLS (Microwave Limb Sounder), and OSIRIS (Optical Spectrograph and InfraRed Imager System) satellite measurements. However, there is a 10–13 % negative bias at 40 km altitude and a 10–50 % positive bias at 50 km for solar zenith angles > 75°. These biases are most likely caused by stray light which is difficult to characterize and to remove entirely from the measured spectra. Nevertheless, the GBL data set approximately doubles the amount of useful GOMOS ozone profiles and improves coverage of the summer pole.
Highlights
The GOMOS (Global Ozone Monitoring by Occultation of Stars) instrument on board the Envisat satellite uses the stellar occultation technique for monitoring ozone and other trace gases in the middle atmosphere (Bertaux et al, 2010)
The large solar zenith angle observations account for 16 % of the GOMOS bright limb (GBL) data and the GOMOS measurement geometry is such that these observations appear mostly at mid and high latitudes
GOMOS daytime data suffer from serious stray light contamination and in particular the upper altitudes are sensitive to the accuracy of the removal method
Summary
The GOMOS (Global Ozone Monitoring by Occultation of Stars) instrument on board the Envisat satellite uses the stellar occultation technique for monitoring ozone and other trace gases in the middle atmosphere (Bertaux et al, 2010). S. Tukiainen et al.: GOMOS bright limb data set retrieving ozone profiles from the GOMOS limb scattered radiances, or GOMOS bright limb (GBL) measurements as they are referred to on. The GOMOS bright limb data set consists of ∼ 358 000 limb-scattered radiance spectra measured around 10:00 LT between March 2002 and April 2012, from the launch of Envisat to the communication failure that stopped the mission From these measurements we have retrieved vertical ozone profiles in the 18–60 km altitude range. MLS measures globally during the day and night, and the accuracy of the MLS ozone profiles is estimated to be better than 5 % in the stratosphere (Froidevaux et al, 2008) In this comparison we used the MLS Level 2 version 3.3 data (Livesey et al, 2011). The two available OSIRIS ozone products agree with each other within a couple of percents
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