Colloquium: Dr. Paul Newman, NASA Goddard

Paul A. Newman¹, Olga Tweedy², Lawrence Coy¹, Natalya Kramarova¹, Leslie R. Lait¹, Mijeong Park³, Steven Pawson¹, William Randel³, Susan Strahan¹,

 ¹NASA GSFC, ²Johns Hopkins Univ. ³NCAR,

ABSTRACT: Here we describe an unprecedented disruption of the stratospheric quasi-biennial oscillation (QBO) QBO during 2015-2017 period. The QBO is a tropical lower stratospheric, downward propagating zonal wind variation, with a period of ~28 months. First discovered in 1960, observations of the QBO extend back to 1953. The QBO propagates downward from the middle stratosphere to the tropopause with a period of about 28 months, with a range of 24-32 months. The QBO is a major source of stratospheric variability, and in addition to influencing the zonal wind behavior, the QBO affects stratospheric temperatures and trace gases, particularly ozone and water vapor. Here we describe the unprecedented disruption of the QBO during the Northern Hemisphere winter of 2015-17 using Singapore wind radiosonde observations and meteorological reanalyses. Normally, the QBO would show a steady downward propagation of the westerly phase. In 2015-17, there was an anomalous upward displacement of this westerly phase from ~30 hPa to 15 hPa. These westerlies impinge on, or “cut-off” the normal downward propagation of the easterly phase. In addition, easterly winds develop at 40 hPa.  Comparisons to tropical wind statistics for the 1953-present record demonstrate that this anomalous 2015-17 QBO is unprecedented. More specifically, this talk will focus on the impact of the QBO disruption on trace gas distributions. The disruption led to a reduction of ozone in the June-September period of the Northern and Southern hemisphere extratropics, along with perturbations to water and hydrochloric acid (HCl). In the NH, these total ozone values were either at or near record low levels.