Regional and seasonal trends in tropical ozone from SHADOZ profiles: Reference for models and satellite products

(b) All stations exhibit FT ozone increases in February-May (up to 15%/decade) when the frequency of convectively driven waves have changed. (c) After May, monthly ozone changes are both positive and negative, leading to mean trends of +(1-4)%/decade, depending on station. (d) LMS ozone losses reach (4-9)%/decade midyear, correlating with an increase in TH as derived from SHADOZ radiosonde data.

(e) When the upper FT and LMS are defined by tropopause-relative coordinates, the LMS ozone trends all become insignificant. Thus, the 20-year decline in tropical LMS ozone reported in recent satellite-based studies likely signifies a perturbed tropopause rather than chemical depletion. The SHADOZ-derived ozone changes highlight regional and seasonal variability across the tropics and define a new reference for evaluating changes derived from models and satellite products over the 1998-2019 period.