Numerical Simulation of Tropospheric Ozone Depletion Events in the Arctic Spring of the Year 2019

Abstract

Ozone depletion is not only observed in the polar stratosphere, but also near the ground. Bromine species originating from sea salt are released from snow in an auto-catalytic reaction cycle and can then deplete ozone, strongly altering the oxidation capacity of the atmosphere. In this study, ozone depletion events in the Arctic between February and May 2019 are studied using the time-dependent, three-dimensional software Weather Research and Forecasting model coupled with Chemistry (WRF-Chem). Two bromine emission schemes are evaluated: first, infinite releasable bromide is assumed and, second, a scheme with a finite bromide release tracked over time is considered. Good agreement of simulation results with observations from two in-situ measuring stations and from ozone sonde flights is found. The finite bromide assumption dramatically improves the simulation results near Utqiaġvik, Alaska and Churchill, Canada in April whereas in February and March, the numerical results are similar, with a slight overall improvement. An underestimation of ozone depletion near Eureka, Canada in both simulations suggests that multi-year ice and snow-covered land near coasts are possibly better bromide sources than previously anticipated.