Quasi-Biennial Oscillation

Quasi-Biennial Oscillation
Name	Quasi-Biennial Oscillation
Abbreviation	QBO
Period	~28 months
Location	Equatorial stratosphere
Discovered	1960s
Primary effect	Stratospheric zonal wind reversal

Contents

Quasi-Biennial Oscillation The Quasi-Biennial Oscillation is a regular alternation of easterly and westerly zonal winds in the tropical stratosphere near the equator, with an average period of about 28 months. This oscillation influences large-scale circulation patterns linked to events observed in NOAA, NASA, Met Office records and discussed in literature from World Meteorological Organization panels and Intergovernmental Panel on Climate Change assessments. Prominent observations and theoretical developments involve researchers associated with University of Cambridge, Massachusetts Institute of Technology, and Imperial College London.

Overview

The phenomenon manifests as a descending pattern of wind regimes in the equatorial stratosphere, first characterized in the 1960s during campaigns involving National Center for Atmospheric Research, Scripps Institution of Oceanography, and Lamont–Doherty Earth Observatory. It modulates stratospheric composition and interacts with radiative processes studied at institutions such as Harvard University, California Institute of Technology, and ETH Zurich. Observational networks run by European Centre for Medium-Range Weather Forecasts, Japan Meteorological Agency, and Australian Bureau of Meteorology provide long-term records used alongside satellite missions from NOAA, European Space Agency, and JAXA.

The driving mechanism is nonlinear momentum deposition by vertically propagating atmospheric waves — principally equatorial Kelvin waves, mixed Rossby–gravity waves, and inertia-gravity waves — identified in theoretical work at Princeton University and University of Colorado Boulder. Wave–mean flow interactions first described in models by researchers from Royal Society-affiliated groups lead to the alternating shear zones; pioneering analyses by scientists linked to British Antarctic Survey and Max Planck Institute for Meteorology formalized the critical-layer absorption processes. Radiative damping influenced by stratospheric ozone chemistry studied at National Center for Atmospheric Research and National Aeronautics and Space Administration laboratories modulates amplitude and period, while coupling to the quasi-stationary Brewer–Dobson circulation connects to work at NOAA and University of Reading.

Measurement approaches combine in situ radiosonde launches from networks managed by World Meteorological Organization partners, satellite retrievals from Aqua (satellite), Suomi NPP, and Envisat missions, and reanalysis products produced by ERA-Interim, ERA5, and NCEP/NCAR. Field campaigns such as those coordinated by International Geophysical Year frameworks and programs at Lamont–Doherty Earth Observatory and Scripps Institution of Oceanography provided early datasets. Instrumentation developments at NOAA's Earth System Research Laboratories and laboratory analyses by groups at Columbia University and University of Tokyo refined wind and temperature profiles used to diagnose phase, amplitude, and vertical descent rates.

The oscillation exerts teleconnections that affect phenomena including tropical cyclone activity analyzed by National Hurricane Center, monsoon variability studied at Indian Institute of Tropical Meteorology and Chinese Academy of Sciences, and midlatitude circulation anomalies examined by European Centre for Medium-Range Weather Forecasts and Met Office. It modulates polar vortex strength related to sudden stratospheric warming events researched at British Antarctic Survey and Danish Meteorological Institute, and influences ozone transport evaluated in work by World Meteorological Organization and United Nations Environment Programme. Interactions with modes such as the El Niño–Southern Oscillation, North Atlantic Oscillation, and Pacific Decadal Oscillation are topics of cross-institutional studies from Scripps Institution of Oceanography, CSIRO, and Lamont–Doherty Earth Observatory.

Long-term analyses using records from NOAA, ERA5, and archives curated by National Centers for Environmental Information reveal epochal variability in period and amplitude, with notable anomalies documented in the late 20th and early 21st centuries. Studies led by researchers at Columbia University, University of Reading, and University of Cambridge have examined possible modulation by volcanic eruptions such as Mount Pinatubo and anthropogenic changes linked to greenhouse gas forcing addressed in Intergovernmental Panel on Climate Change reports. Paleoclimate proxies and model–data comparisons undertaken at Max Planck Institute for Meteorology and Lawrence Berkeley National Laboratory explore longer-term behavior and potential connections to radiative forcing scenarios developed by IPCC authors.

Numerical simulation of the oscillation uses high-top general circulation models developed at European Centre for Medium-Range Weather Forecasts, National Center for Atmospheric Research, and Met Office Hadley Centre that explicitly resolve stratospheric dynamics and wave spectra. Predictability studies by groups at NOAA's Geophysical Fluid Dynamics Laboratory, Princeton University, and University of Oxford examine ensemble initialization, data assimilation from COSMIC and GPS radio occultation missions, and model biases tied to convective parameterizations tested at Lawrence Livermore National Laboratory and Los Alamos National Laboratory. Operational forecasting systems maintained by ECMWF, JMA, and UK Met Office incorporate QBO signals to improve seasonal and subseasonal predictions relevant for stakeholders including World Meteorological Organization centers and national climate services.

Category:Atmospheric dynamics