Assessment of Odin-OSIRIS ozone measurements from 2001 to the present using MLS, GOMOS, and ozonesondes

Abstract

Abstract. The Optical Spectrograph and InfraRed Imaging System (OSIRIS) was launched aboard the Odin satellite in 2001 and is continuing to take limb-scattered sunlight measurements of the atmosphere. This work aims to characterize and assess the stability of the OSIRIS 11 yr v5.0x ozone data set. Three validation data sets were used: the v2.2 Microwave Limb Sounder (MLS) and v6 Global Ozone Monitoring by Occultation of Stars (GOMOS) satellite data records, and ozonesonde measurements. Global mean percent differences between coincident OSIRIS and validation measurements are within 5 % at all altitudes above 18.5 km for MLS, above 21.5 km for GOMOS, and above 17.5 km for ozonesondes. Below 17.5 km, OSIRIS measurements agree with ozonesondes within 5 % and are well-correlated (R > 0.75) with them. For low OSIRIS optics temperatures (< 16 • C), OSIRIS ozone measurements have a negative bias of 1-6 % compared with the validation data sets for 25.5-40.5 km. Biases between OSIRIS ascending and descending node measurements were investigated and found to be related to aerosol retrievals below 27.5 km. Above 30 km, agreement between OSIRIS and the validation data sets was related to the OSIRIS retrieved albedo, which measures apparent upwelling, with a positive bias in OSIRIS data with large albedos. In order to assess the long-term stability of OSIRIS measurements, global average drifts relative to the validation data sets were calculated and were found to be < 3 % per decade for comparisons with MLS for 19.5-36.5 km, GOMOS for 18.5-54.5 km, and ozonesondes for 12.5-22.5 km. Above 36.5 km, the relative drift for OSIRIS versus MLS ranged from ∼ 0 to 6 % per decade, depending on the data set used to convert MLS data to the OSIRIS altitude versus number density grid. Overall, this work demonstrates that the OSIRIS 11 yr ozone data set from 2001 to the present is suitable for trend studies.

Trend and variability in ozone in the tropical lower stratosphere over 2.5 solar cycles observed by SAGE II and OSIRIS

“…Degenstein et al (2009) showed the version 5 data to be valid to 2 % down to 18 km by comparisons with SAGE II. The version 5.07 data (available at ftp://odin-osiris.usask.ca/Level2/daily) have been validated most recently and extensively by Adams et al (2013Adams et al ( , 2014. In the tropical upper troposphere, version 5 biases vs. ozonesondes and aircraft observations reach + 5 % (Cooper et al, 2011).…”

“…For OSIRIS, we include only the observations made in the descending node of the orbit to avoid a scattering angle dependence of the retrieved ozone arising from residual aerosol interference that, if neglected, could lead to a trend in ozone as the proportion of ascending and descending node observations has changed over the mission lifetime. The Equator-crossing time in the descending and ascending nodes is ∼ 06:30/∼ 18:30, respectively (McLinden et al, 2012;Adams et al, 2014) having slightly precessed from 06:00/18:00. , resulting in no recent equatorial measurements in the ascending node.…”

Intercomparison of vertically resolved merged satellite ozone data sets: interannual variability and long-term trends

“…To date, three single-instrument extensions have been made to the SAGE-II record. These include one case extended with limb-scattered measurements from OSIRIS (Optical Spectrograph and Infrared Imager System) onboard the Odin satellite (2001-present) Adams et al, 2014;Sioris et al, 2014) and two cases using the stellar occultation measurements from GOMOS …”

Drift-corrected Odin-OSIRIS ozone product: algorithm and updated stratospheric ozone trends

“…They also noted that the long-term stability of OSIRIS up to 2012 was assessed by Adams et al (2014) using comparisons between OSIRIS, GOMOS, the Microwave Limb Sounder (MLS), and ozonesondes. This analysis showed that the OSIRIS data product did show some regions of positive drift (meaning higher ozone values) with respect to the other data sets, particularly after 2010; however, the global average drifts were < 3 % per decade between approximately 18 and 45 km.…”