| Session Details | |
| Section | SS - Special Sessions |
| Session Title | The Quasi-biennial Oscillation and Its Role in the Climate System |
| Main Convener | Dr. Jack A. Kaye (National Aeronautics and Space Administration (NASA), United States) |
| Co-convener(s) | |
| Session Description | The quasi-biennial oscillation (QBO) is an approximate 2-year quasi-periodic oscillation of easterly and westerly zonal winds in the equatorial stratosphere. 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 driven by vertically propagating Kelvin, mixed Rossby-gravity waves, and smaller-scale gravity waves in the equatorial region. In addition to influencing the zonal wind behavior, the QBO affects stratospheric temperatures and trace gases, particularly ozone and water vapor. These impacts are primarily driven by the QBO meridional and vertical secondary circulation, and effects extend into the sub-tropics and high latitudes of both hemispheres. In addition to being a major source of stratospheric variability, the QBO also impacts tropospheric weather in both the tropics and extratropics. Recent research has shown that during the 2015-2016 winter, the QBO 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. This disruption was unprecedented in the 1953-present observational record (primarily the Singapore radiosonde time series), and the disruption caused anomalous impacts on stratospheric temperatures and trace gas distributions. In this session, we will discuss new QBO science, this recent QBO disruption, including possible causes and consequences of the disruption. In addition, we will further explore the impact on the stratosphere-troposphere system and the implications for future projections. |