A theoretical study of the quasibiennial oscillation in the tropical. During the easterly qbo phase qboe, the stratospheric polar vortex weakens in response to arctic seaice anomalies. Pdf quasibiennial oscillation above 10 mb researchgate. Realistic quasi biennial oscillations in a simulation of the global climate adam a.
In uence of the qbo and enso on the nh stratospheric polar vortex peter watson, first year report, aopp 2. These winds became known as the krakatoa easterlies. Quasibiennial oscillation of the stratosphere youtube. Surface impacts of the quasi biennial oscillation atmoschemphys. The quasibiennial oscillation qbo is an alternating pattern of westerly and easterly zonal mean winds observed in the equatorial stratosphere. Many of the dynamical as pects of the qbo are best illustrated by a timeheight cross section of monthlymean equatorial zonal longi tudinal wind plate 1. The quasibiennial oscillation is the stratospheres old faithful, said paul newman. This quasibiennial oscillation qbo has been observed to dominate the winds in this region of the atmosphere for at least the last 6 decades and is characterized by a. A strange thing happened in the stratosphere a 60year pattern in the stratosphere changes up. Westerlies are shaded, and the darkness increases at intervals of5ms21 which is the contour interval. The quasibiennial oscillation qbo dominates the variability of the equatorial stratosphere 1650 km and is easily seen as downward propagating easterly and westerly wind regimes, with a variable period averaging approximately 28 months. The quasibiennial oscillation qbo is a quasiperiodic oscillation of the equatorial zonal wind between easterlies and westerlies in the tropical stratosphere with a mean period of 28 to 29 months. Effects of the stratospheric quasibiennial oscillation on. Quasibiennial oscillation qbo anomalous change youtube.
It is mainly driven 36 by the vertically propagating waves with easterly and westerly phase speed that. Northern oscillation index is an index of climate variability based on the difference in slp anomalies at the north pacific high and near darwin australia. Evaluation of the quasi biennial oscillation in global climate models for the sparc qboinitiative a. In claytons day observations were scarce and the quasibiennial oscillation qbo in the equatorial stratospheric winds was not known, and since many. Linking the quasi biennial oscillation and projected arctic seaice loss to stratospheric variability in early winter. Does the holtontan mechanism explain how the quasi. These two jets interact, and in particular, the former modulates the latter by the much observed. One of the main sources of predictable external vari ability is the quasibiennial oscillation qbo. For this purpose, the max planck institute earth system model mpi. The statistical prediction of east african rainfalls using.
Highres pdf version data file as above, but with annual cycle removed and a 5month gaussian. The oscillation has an average period of 26 months and a maximum amplitude of about 20 m s 1 and is symmetric about the equator occurring between 12 s and 12 n. This is caused by the increased aerosol heating and associated warming in the tropical lower stratosphere and higher residual vertical velocity. Several investigators have reported the presence of the qbo in various atmospheric pa. Learn vocabulary, terms, and more with flashcards, games, and other study tools. The quasibiennial oscillation qbo is a tropical lower stratospheric, downward propagating zonal wind variation, with an average period of. Pdf it is shown that the quasibiennial oscillation of the equatorial lower stratosphere was correlated with mean zonal wind in the. Quasibiennial oscillation and solar cycle influences on. Citeseerx document details isaac councill, lee giles, pradeep teregowda. Many authors speculated about the link between the qbo in solar and geomagnetic activity.
Defining metrics of the quasibiennial oscillation in global climate. The northernhemisphere winter stratosphere is home to two large jets. Quasibiennial cycles are often reported in climate studies. A n excellen t description of the current understanding of the quasi bien nial oscillation s of wind, tem perature and ozone can be found in work by baldwin et al. Extratropical atmospheric predictability from the quasibiennial oscillation and madden julian oscillation in s2s models. Once the files have been converted, you must approve the new pdf files before the submission is complete. Dynamical response to the qbo in the northern winter. The importance of the qbo is that it dominates the variability of the tropical lower stratospheric meteorology wallace, 1973. Garfinkel department of earth and planetary science, johns hopkins university, baltimore, maryland. Pdf the quasibiennial oscillation qbo dominates the variability of the equatorial stratosphere 16 50 km and is easily seen as downward. The quasibiennial oscillation qbo for our colleagues nasa. From a fluid dynamical perspective, the qbo is a fascinating example of a.
In 1883, the krakatoa volcano in indonesia erupted, transporting volcanic ash and dust into the stratosphere. These are simple mathematical models that capture the essence of qbo synchronization by focusing on the dynamics of the height of the zero wind line. Currently available wind data from the equatorial stratosphere extend back to 1953. Quasibiennial oscillation in gps vtec measurements. In addition, an increase in cold extremes in eurasia only occur during qboe winters due to seaice decline. It is primarily an oscillation in zonal winds in the stratosphere between downward propagating easterly and westerly phases, with a period of 2232 months reed et al. The alternating wind regimes develop at the top of the lower stratosphere and propagate downwards at about 1 km 0. The response of the quasibiennial oscillation qbo to an imposed mean upwelling with a periodic modulation is studied, by modeling the dynamics of the zero wind line at the equator using a class of equations known as descent rate models.
The quasibiennial oscillation qbo dominates the variability of the equatorial stratosphere 16 50 km and is easily seen as downward propagating easterly and westerly wind regimes, with a. The tropical quasi biennial oscillation is one of the most spectacular examples of low frequency variabil ity observed in the earths atmosphere, yet the. Quasibiennial oscillation qbo freie universitat berlin. Here, the state of the stratosphere is represented by the phase of the quasibiennial oscillation qbo. A strange thing happened in the stratosphere eurekalert. This study investigates seasonal modulations of the quasi. The zmzw and zmt are strongly coupled by the thermal wind equation so that a \strong vortex has high zmzw and low zmt.
A theory for the quasibiennial oscillation based on. Although it wasnt realized at the time, the quasibiennial oscillation qbo was observed during the 1883 eruption of krakatoa, when the ash from the volcano was transported around the globe from east to west by stratospheric winds in about two weeks. Tim stockdale, who represented ecmwf at the meeting, explains what the qbo is all about. Another important factor is the quasibiennial oscillation. A strong relationship between the quasibiennial oscillation qbo of equatorial stratospheric winds and the amplitude of the maddenjulian oscillation mjo during the boreal winter has recently been uncovered using observational data from the mid1970s to the present. Extratropical atmospheric predictability from the quasi.
The early development of the 20152016 quasibiennial. Results from the met o ce hadgem2ccs general circulation model are presented. With the use of a 2d version of our numerical spectral model nsm that incorporates hines doppler spread parameterization dsp for gravity waves gw. This makes an easterly phase likely as we head into the winter of 201718. Accompanying the zonal wind qbos are anomalies of temperature, trace constituents, and mean meridional circulation. Introduction 33 the quasibiennial oscillation qbo is the most prominent circulation pattern in the trop 34 ical stratosphere, featuring alternating easterlies and westerlies that slowly descend from the 35 stratopause to the tropopause baldwin et al. Quasibiennial oscillation how is quasibiennial oscillation abbreviated. Does the holtontan mechanism explain how the quasibiennial oscillation modulates the arctic polar vortex. This paper addresses the impact of the quasibiennial oscillation qbo on the backgrounderror covariances in the tropical atmosphere of the ecmwf model. Maddenjulian oscillation and quasibiennial oscillation bd mundhenk et al.
Effects of the stratospheric quasibiennial oscillation on longlived greenhouse gases in the troposphere kevin hamilton geophysical fluid dynamics laboratory, noaa, princeton university, princeton, new jersey songmiao fan atmospheric and oceanic sciences program, princeton university, princeton, new. Quasidecadal oscillations qdo have been observed in the stratosphere and have been linked to the equatorial quasibiennial oscillation qbo and to the 11year solar activity cycle. They are alternately easterly and westerly, reversing about every months. They blow at velocities of 15 to 35 metres per second about 35 to 80 miles per hour. Biennial oscillation in subseasonal forecast models. The quasibiennial oscillation was the subject of a workshop in the canadian city of victoria from 16 to 18 march. The basic physical mechani sms of the phenomenon wer e explaine d by holton and lindzen 1972.
Figure 2 shows the process of metric derivation using the reanalyses. Downward propagating easterly green and westerly red winds and their induced meridional circulation black contours with arrows for different phases of the qbo. Influence of the quasibiennial oscillation on the ecmwf model. A strong relationship between the quasibiennial oscillation qbo of equatorial stratospheric winds and the amplitude of the maddenjulian. The qbo is also important for seasonal forecasting, and the qbo. The total column ozone tco observed from satellites and assimilated in the european centre for mediumrange weather forecasts since 1979 is used as an atmospheric tracer to study the modulations of the winter arctic stratosphere. The quasibiennial oscillation qbo of the equatorial lower and middle stratosphere is a fairly regular 2 to 3year cycle characterized by alternating descending regimes of easterly westward propagating and westerly eastward propagating zonal wind figure 1. The qbo is also important for seasonal forecasting, and the qbo controls stratospheric ozone and water variability that can modulate surface ultraviolet uv and infrared ir radiation. Descent rate models of the synchronization of the quasi.
The quasibiennial oscillation, qbo, a well known periodicity in the equatorial stratospheric zonal winds, is also found in ionospheric parameters and in solar and geomagnetic activity indices. The quasibiennial oscillation is the equatorial zonal wind between easterlies and westerlies in the tropical stratosphere with a period of 26 months on average. A composite plot of the quasibiennial oscillation qbo according to the easterlywesterly transition at 20 hpa. It is known that enso affects corn yieldthroughweather patterns,nao. A quasibiennial oscillation qbo of the zonal wind in the tropical stratosphere was first reported in the early 1960s by reed et al. Many of the dynamical aspects of the qbo are best illustrated by a timeheight cross section of monthlymean equatorial zonal longitudinal wind plate 1.
Warner david stainforth, warwick norton john austin abstract. The quasibiennial oscillation is the stratospheres old faithful, said paul newman, chief scientist for earth sciences at nasas goddard space flight center, greenbelt, maryland, and lead. The quasibiennial oscillation introduction to the qbo the discovery over the quasibiennial oscillation, or qbo, can be traced to two events. If you do not approve the pdf files, your manuscript will not be submitted.
Spatial patterns and mechanisms of the quasibiennial. The quasibiennial oscillation qbo is a tropical, lower stratospheric, downward propagating zonal wind variation, with an average period of 28 months. Quasibiennial oscillation an overview sciencedirect. In claytons day observations were scarce and the quasibiennial oscillation qbo in the equatorial stratospheric winds was not known, and since many scientists then as now accept only phenomena which they can explain, claytons findings were. On the emerging relationship between the stratospheric. Rebooting the quasibiennial oscillation qbo the unusual tropical stratospheric winds of 2016. Skillful empirical subseasonal prediction of landfalling. Here we present reconstructions of the qbo extending back to 1900 that can be used to constrain climate model simulations.