Characterization and correction of Global Ozone Monitoring Experiment 2 ultraviolet measurements and application to ozone profile retrievals

Abstract

We present an assessment study of the Global Ozone Monitoring Experiment 2 (GOME‐2) reflectance for the wavelength range 270–350 nm by comparing measurements with simulations calculated using the vector linearized discrete ordinate radiative transfer model (VLIDORT) and Microwave Limb Sounder (MLS) ozone profiles. The results indicate wavelength‐ and cross‐track‐position‐dependent biases. GOME‐2 reflectance is overestimated by 10% near 300 nm and by 15%–20% around 270 nm. Stokes fraction measurements made by onboard polarization measurement devices are also validated directly using the VLIDORT model. GOME‐2 measurements agree well with the simulated Stokes fractions, with mean biases ranging from −1.0% to ∼2.9%; the absolute differences are less than 0.05. Cloudiness‐dependent biases suggest the existence of uncorrected stray‐light errors that vary seasonally and latitudinally. Temporal analysis indicates that reflectance degradation began at the beginning of the mission; the reflectance degrades by 15% around 290 nm and by 2.2% around 325 nm from 2007 through 2009. Degradation shows wavelength‐ and viewing‐angle‐dependent features. Preliminary validation of ozone profile retrievals with MLS, Michelson Interferometer for Passive Atmospheric Sounding, and ozonesonde reveals that the application of radiometric recalibration improves the ozone profile retrievals as well as reduces fitting residuals by 30% in band 2b.