Relations between cyclones and ozone changes in the Arctic using data from satellite instruments and the MOSAiC ship campaign

Large-scale meteorologic events (e.g. cyclones), referred to as synoptic events, strongly influence weather predictability but still cannot be fully characterised in the Arctic region because of the sparse coverage of measurements. Due to the fact that atmospheric dynamics in the lower stratosphere and troposphere influence the ozone field, an approach to analyse these events further is the use of space-borne measurements of ozone vertical distributions and total columns. In this study we investigate the link between cyclones and changes in stratospheric ozone by using a combination of unique measurements during the MOSAiC ship expedition, ozone profile and total column observations by satellite instruments (OMPS-LP, TROPOMI), and ERA5 reanalysis data. Three special cases during the MOSAiC expedition were selected and classified for the analysis. They consist of one 'normal' cyclone, where a low surface pressure coincides with a minimum in tropopause height, and two 'untypical' cyclones, where this is not observed. The influence of cyclone events on ozone in the upper-troposphere lower-stratosphere (UTLS) region was investigated, using the fact that both are correlated with tropopause height changes. The negative correlation between tropopause height from ERA5 and ozone columns was investigated in the Arctic region for the three-month period from June to August 2020. This was done using total ozone columns and subcolumns from TROPOMI, OMPS-LP and MOSAiC ozonesonde data. The greatest influence of tropopause height changes on ozone contour levels occurs at an altitude between 10 and 20 km. Moreover, the lowering of the 250 ppb ozonopause (about 11 km altitude) below 9 km was used to identify and track cyclones using OMPS-LP ozone observations. The potential of this approach was demonstrated in two case studies where the boundaries of cyclones could be determined using ozone observations. The results of this study can help improve our understanding of the relationship between cyclones, tropopause height, and ozone in the Arctic and demonstrate the usability of satellite ozone data for investigating cyclones in the Arctic.