Comment on “Observation of large and all-season ozone losses over the tropics” [AIP Adv. 12, 075006 (2022)]

Abstract

Lu (2022) (hereafter L2022) used the Trajectory-mapped Ozonesonde dataset for the Stratosphere and Troposphere (TOST) to argue that there has been very substantial ozone depletion (>80%) in the tropical (30°S–30°N) lower stratosphere (LS) since the 1960s. This was labeled a “large and all-season ozone hole.” Here, we show that this claim is false due to erroneously large tropical ozone values in the interpolated sparse historical TOST data. In addition, L2022 repeats the suggestion made in a number of the author’s earlier papers that cosmic rays are involved in stratospheric ozone depletion. This claim is also not valid; a huge body of work has explained the observed stratospheric ozone depletion through a well-established gas phase and heterogeneous chemistry following the emission of ozone-depleting substances (ODSs) through human activities. We expand on these points below. In particular, we present a simple analysis of the TOST dataset used by L2022 and show its unsuitability for the application performed. In contrast, we then summarize the much smaller observed variations in ozone in the tropical LS based on many international efforts of data validation and quality assurance, which are not cited by L2022. We then discuss flaws in the cosmic-ray electron-induced mechanism proposed by L2022 as being the main driver of stratospheric ozone losses.