Ozone recovery as detected in NOAA Ground-Based and Satellite Ozone Measurements

The 1987 Montreal Protocol and its 1990 amendments to the US Clean Air Act require NASA and NOAA to monitor ozone and the reduction of ozone depleting substances (ODS). The 2018 WMO/UNEP Ozone Assessment ¹ and the Long-term Ozone Trends and Uncertainties in the Stratosphere (LOTUS) special report ² indicate that the extent of ozone recovery is geographically diverse. These studies focus on Multi-linear Regression analyses (MLR) optimized for broad latitudinal bands. NOAA's ground-based instruments (GB) include Dobson total column ozone observations, vertical distribution of ozone from Dobson Umkehr and ozonesonde profiling. Additionally NOAA's homogenized satellite record from SBUV, SBUV/2 and OMPS provide information on ozone vertical distribution globally allowing the study of large scale ozone variability. The meteorological models MERRA2 and GFS and the GMI chemistry transport model allow the exploration of diurnal variability in the satellite records and the tracking of air parcels relevant to the representativeness of the GB data. This study will review and revise historical WMO GAW and NOAA Umkehr records with improved stray light corrections. Overpass data will be generated for the GB sites using the combination techniques of the NOAA Cohesive zonal ozone product. The LOTUS MLR model will be reviewed and optimized for single point GB datasets. The optimized MLR will be used to determine ozone profile trends at the GB sites. Satellite data and model records will be used to explore the impact of the sampling limitations of the GB data on long term trends and provide insight on the ability of the GB network to accurately depict ozone trends. Progress on this project will be presented.

1- WMO (World Meteorological Organization), Scientific Assessment of Ozone Depletion: 2018, World Meteorological Organization, Global Ozone Research and Monitoring Project - Report No. 58, Geneva, Switzerland, 2018.

2- SPARC/IOC/GAW (2018): SPARC/IOC/GAW report on Long-term Ozone Trends and Uncertainties in the Stratosphere. SPARC Report No. 9, WCRP-17/2018, GAW Report No. 241, doi: 10.17874/f899e57a20b.