GOME O3 Profiling with Degradation Correction

We present a simple method to perform degradation correction to Global Ozone Monitoring Experiment (GOME) reflectance spectra by comparing the average reflectance for 60 • N–60 • S with that at the beginning of GOME observations after removing the dependences on solar zenith angle and seasonal variation. The results indicate positive 5 degradation of up to ∼15–25% in the wavelength range 289–370 nm during 2000– 2002; the degradation also exhibits significant dependence on wavelength and view zenith angle. These results are consistent with previous studies using radiative transfer models and ozone observations or climatology. The degradation causes retrieval biases of up to ∼3% (10 DU, 1 DU=2.69×10 16 molecules cm −2), 30% (10 DU), 10%, 10 and 40% in total column ozone, tropospheric column ozone, stratospheric ozone and tropospheric ozone, respectively, from our GOME ozone profile retrieval algorithm. The application of this degradation correction generally improves the retrievals relative to Dobson and ozonesonde measurements during 2000–2003 and improves the retrieval consistency during 1996–2003.