Abstract
Abstract. Severe vortex-wide ozone loss in the Arctic would expose both ecosystems and several millions of people to unhealthy ultraviolet radiation. Adding to these worries, and extreme events as the harbingers of climate change, exceptionally low ozone with column values below 220 DU occurred over the Arctic in March and April 2020. Sporadic occurrences of low ozone with less than 220 DU at different regions of the vortex for almost 3 weeks were found for the first time in the observed history in the Arctic. Furthermore, a large ozone loss of about 2.0–3.4 ppmv triggered by an unprecedented chlorine activation (1.5–2.2 ppbv) matching the levels occurring in the Antarctic was also observed. The polar processing situation led to the first-ever appearance of loss saturation in the Arctic. Apart from these, there were also ozone-mini holes in December 2019 and January 2020 driven by atmospheric dynamics. The large loss in ozone in the colder Arctic winters is intriguing and demands rigorous monitoring of the region.
Highlights
Apart from its significance of shielding us from the harmful ultraviolet (UV) radiation reaching the surface of earth, stratospheric ozone is a key component in regulating the climate (e.g. Riese et al, 2012)
The higher temperatures in early winter and limited chlorine activation were the reasons for relatively smaller ozone loss in 1997, it was a winter with a strong vortex up to the end of April (Coy et al, 1997; Feng et al, 2007; Kuttippurath et al, 2012)
Since minor warmings are very common in the Arctic winters, we examined the occurrence of mW events by checking the temperature at 90◦ (North Pole) and 60◦ N at 10 hPa and zonal winds at 60◦ N at 10 hPa
Summary
Apart from its significance of shielding us from the harmful ultraviolet (UV) radiation reaching the surface of earth, stratospheric ozone is a key component in regulating the climate (e.g. Riese et al, 2012). Kuttippurarth et al (2012) observed an increasing trend in major warmings, and ozone loss is found to be proportional to the timing of the major warmings, as early winter warmings stop polar stratospheric cloud (PSC) formation (i.e. stop the action of heterogeneous chemistry) because of the higher temperatures. This situation limits the activated chlorine available for ozone loss and results in a smaller loss in warm Arctic winters. This is important as the winter was very cold in the stratosphere, with the largest ozone loss in the observational record, and it experienced total column ozone (TCO) values below 220 DU for several days in the vortex
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