Publication Date

Fall 2019

Degree Type


Degree Name

Master of Science (MS)


Meteorology and Climate Science


Minghui Diao


Aircraft Observations, Climate Chemistry Model, Ozone, Reanalysis Simulations, Tropical Troposphere, Water Vapor

Subject Areas

Meteorology; Atmospheric chemistry; Atmospheric sciences


Tropospheric ozone (O3) negatively is a greenhouse gas, affecting global climate. To improve climate predictions, the behavior of O3 and the mechanisms affecting its distribution must be understood and accurately represented in model simulations. This study evaluates O3 and water vapor (H2O) observations from the Convective Transport of Active Species in the Tropics (CONTRAST) campaign with data from the National Center for Atmospheric Research’s (NCAR) Community Atmospheric Model with Chemistry (CAM-Chem), the Modern-Era Retrospective Analysis for Research and Applications version 2 (MERRA-2), and the European Centre for Medium-Range Weather Forecast (ECMWF) Re-Analysis-Interim (ERA-Interim). In the tropical middle troposphere, CAM-Chem shows similar O3 distributions to the observations, while MERRA-2 and ERA-Interim show higher O3 concentrations. An anti-correlation between O3 and H2O is observed between potential temperature of 320 K and 340 K. MERRA-2 and ERA-Interim show a weak anti-correlation between O3 and H2O for the same potential temperature range. Further analysis shows that MERRA-2 and ERA-Interim have a spatial mismatch between high O3 and low H2O, affecting the anti correlated relationship between O3 and H2O. The results of this study show that MERRA-2 and ERA-Interim generally show higher O3 values in the tropics than the observations, leading to a spatial mismatch between high O3 concentrations and low H2O.