Analysis of Trace Gases Response on the Anomalous Change in the QBO in 2015-2016

The quasi-biennial oscillation (QBO) is a quasi-periodic alternation between easterly and westerly zonal winds in the tropical stratosphere. The alternating wind regimes propagate downward from the middle stratosphere to the tropopause with a period that varies from 24 to 32 months ( 28 months on average). The QBO wind oscillations affect distribution of chemical constituents, such as ozone (O3), water vapor (H2O), nitrous oxide (N2O) and hydrochloric acid (HCl), due to QBO induced circulation changes. In the 2015-2016 winter, radiosonde observations revealed an anomaly in the downward propagation of the westerly phase, which was disrupted by the upward displacement of the westerly phase from 30 hPa up to 15 hPa, and the sudden appearance of easterlies at 40 hPa. Such a disruption has never been observed in the equatorial wind observations since 1953. In this study we show the response of trace gases to this QBO disruption and quantify statistical significance of the observed changes using O3, H2O, N2O and HCl from satellite sensors (Aura MLS, Suomi NPP OMPS and SBUV) and H2O and O3 from tropical sondes. Preliminary analysis reveals a development of positive anomalies in stratospheric equatorial ozone and hydrochloric acid 40 - 20 hPa in April-July of 2016 as a response to the unusual QBO event. An important focus of the study is on the implications of these trace gas anomalies for the dynamics and chemistry of the stratosphere. In particular, we investigate effects caused by this disrupted QBO on the seasonal transport, residual circulation and evolution of the 2016 Antarctic ozone hole.