A Comparison of 37 Years of Version 9 Total Column Ozone Satellite Data and Ground-based Measurements.

Total column ozone data from the Nimbus-7 Total Ozone Mapping Spectrometer (TOMS), EOS-Aura Ozone Monitoring Instrument (OMI), and Suomi NPP Ozone Mapping and Profiler Suite (OMPS) instruments have been reprocessed with the Version 9 (V9) ozone retrieval algorithm. This algorithm retrieves total ozone from a small number of discrete wavelengths in the Huggins ozone absorption band using the Rodgers optimal estimation method by integrating a coarse retrieved ozone profile. The TOMS V9 algorithm supplies error estimates for each individual total ozone retrieval and also provides retrieval operators such as column weighting kernels that report on the performance of the algorithm over a the range of observation conditions where the sensors collect measurements.

The data from this version 9 processing have been systematically compared to total ozone data from Brewer and Dobson spectrophotometers for an ensemble of individual ground stations as a function of time, satellite solar zenith angle, reflectivity (cloud cover) and latitude. The time series comparisons show a good agreement over the past 37 years and the bias approaching zero over the past decade. This highly accurate, multi instrument data record can be used in long-term ozone trend analysis. The quality of the V9 total ozone is similar to V8, thus the main advantages of this dataset is the additional information on errors and performance it provides, and an overall simplification of the algorithm relative to the previous version.