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Topic: Quasi biennial oscillation

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	Quasi-biennial oscillation - Wikipedia
		The QBO (quasi-biennial oscillation) is a quasi-periodic oscillation of easterlies and westerlies in the tropical stratosphere with a mean period of 28 months.
		The precise nature of the waves responsible for this effect was heavily debated, in recent years however gravity waves have come to be seen as a major contributor.
		Effects of the QBO include mixing of stratospheric ozone by its secondary circulation, modification of monsoon precipitation, and an influence on stratospheric circulation in Northern hemisphere winter (the sudden stratospheric warmings).
	wikipedia.findthelinks.com /qb/QBO.html (160 words)

	Quasi-biennial oscillation - Wikipedia, the free encyclopedia
		The QBO (quasi-biennial oscillation) is a quasi-periodic oscillation of the equatorial zonal wind between easterlies and westerlies in the tropical stratosphere with a mean period of 28 months.
		The QBO was discovered in the 1950s, but its origin remained unclear for some time.
		Effects of the QBO include mixing of stratospheric ozone by the secondary circulation caused by the QBO, modification of monsoon precipitation, and an influence on stratospheric circulation in northern hemisphere winter (the sudden stratospheric warmings).
	en.wikipedia.org /wiki/QBO (312 words)

	The Quasi-Biennial zonal wind Oscillation (QBO) (Site not responding. Last check: 2007-10-23)
		The QBO is roughly between 10mb and 100mb in height extent.
		1) The phase of the QBO affects hurricanes in the Atlantic and is widely used as a prognostic in hurricane forecasts.
		Haynes, P.H., 1998: The latitudinal structure of the quasi-biennial oscillation.
	ugamp.nerc.ac.uk /hot/ajh/qbo.htm (1570 words)

	Biennial Oscillation in Temperature and Monsoon Activity
		The phase of the Tropospheric Biennial Oscillation (TBO) in temperature does not vary with height from surface to the level of tropopause and is found to be associated with the intensity of the monsoon rainfall.
		Quasi Biennial Oscillation (QBO) in zonal wind is a dominant natural oscillation in the equatorial lower stratosphere.
		A strong biennial component is seen in the ENSO phenomena (Rasmusson et al, 1990; Roplewski et al, 1992) and is proved to be an integral part of the Asia-Pacific climate.
	www.atmosp.physics.utoronto.ca /SPARC/SPARC2000_new/PosterSess1/SessionP1_6/Mohanakumar/sparc-1.htm (2242 words)

	Interannual variabilty of the Indian Ocean
		Yet, the ability to predict the future course of the Southern Oscillation was severely hampered by a vagueness in the observational relationships and by the failure to identify underlying physical processes which might have allowed the relationships between the Indian monsoon and the SO to become unravelled (Webster and Yang, 1992).
		A biennial mechanism involving coupled atmosphere-land-ocean interactions is postulated that involves the monsoon as an active participant in the TBO.
		Higher-fequency components such as the biennial period, exist in the SOI besides the basic four-to five year period that may be expected from simple wave or lagged-oscillator theories of the Pacific Ocean.
	indianocean.free.fr /interann.htm (3851 words)

	The Stratospheric Quasi-Biennial Oscillation in the NCEP Reanalyses: Climatological Structures
		A new quasi-biennial oscillation (QBO) indexing method is presented, which is based on the zonal mean zonal wind shear anomaly at the equator and is compared to the Singapore index.
		The meridional distribution of the range in QBO zonal wind is compared with the stratospheric annual cycle, with the annual cycle dominating poleward of 12 degrees latitude but still being significant in the deep tropics.
		It is noteworthy that the NCEP QBO amplitude and the relationships among the reanalyzed zonal wind, temperature, and meridional circulation undergo a substantial change around 1978.
	www.meteor.wisc.edu /~mag/NCEPReanalysesAbstract.html (269 words)

	Met Office: Simulation of quasi-biennial oscillations
		The period and amplitude of the QBO are within the observational bounds of 2-3 years and 20-40 m/s respectively (lower panel).
		The weak oscillation in upper stratospheric easterlies found in previous versions of the model has been replaced by a more variable oscillation with amplitude ~15 m/s and westerlies in the upper stratosphere/lower mesosphere.
		Current observational estimates support our approach to modelling the QBO since a large part of the forcing for the QBO is now thought to come from gravity waves; see Sato and Dunkerton (1997) and Dunkerton (1997) for recent evidence.
	www.metoffice.gov.uk /research/stratosphere/modelling/qbo.html (235 words)

	QBO (Site not responding. Last check: 2007-10-23)
		The Quasi-Biennial Oscillation (QBO)is an east-west oscillation in stratospheric winds above the equator with a period ranging between 22 to 32 months.The different phases of the QBO are known to be associated with shifts in the number and intensity of tropical cyclones and with temperature and precipitation extremes at the earth 's surface.
		QBO information and monitoring - Links to a number of sites with data on the QBO and its role in climate.
		Oscillations primer - An RPI report on the QBO, AO, and Madden-Julian Oscillation and their influence on extreme meteorological events.
	www.bbsr.edu /rpi/public/resedu/qbo.html (210 words)

	Tim Dunkerton__________________________
		Baldwin, M.P. and T.J. Dunkerton, 1999: Propagation of the Arctic Oscillation from the stratosphere to the troposphere.
		Delisi, D.P. and T.J. Dunkerton, 1988: Equatorial semiannual oscillation in zonally averaged temperature observed by the Nimbus 7 SAMS and LIMS.
		Garcia, R.R., T.J. Dunkerton, R.S. Lieberman and R.A. Vincent, 1997: Climatology of the semiannual oscillation of the tropical middle atmosphere.
	www.nwra.com /resumes/dunkerton/publications.html (1666 words)

	Atmospheric Quirks--Oscillation of Equatorial Winds (Site not responding. Last check: 2007-10-23)
		This "quasi-biennial oscillation," as it is called, is a periodic variation in which the direction of the winds in the equatorial stratosphere changes between eastward and westward every 14 months.
		For the first time, it proved to the atmospheric sciences community that oscillating phenomena can arise from a complex interplay of natural, intrinsic processes in the atmosphere rather than having to be the direct function of an oscillation in external factors such as solar output or ocean temperature.
		The quasi-biennial oscillation plays an important role in the transport of ozone from equatorial regions, where the greatest amounts are generated, to higher latitutudes, where the ozone-depleting effects of chlorofluorocarbons are most severe.
	www.washington.edu /research/pathbreakers/1960e.html (424 words)

	ipedia.com: Oscillation Article (Site not responding. Last check: 2007-10-23)
		Oscillation is the periodic variation, typically in time, of some measure as seen, for example, in a swinging pendulum.
		The simplest oscillating system is a mass, subject to the force of gravity, attached to a linear spring.
		In the spring-mass sytem, oscillations occur because, when at the static equilibrium displacement, the mass has kinetic energy which is converted into energy stored in the spring at the extremes of its path.
	www.ipedia.com /oscillation.html (702 words)

	Jahrbuch-CD der MPG 2003 - Forcing of the quasi-biennial o
		However, the ability to simulate a dominant stratospheric phenomenon, the Quasi-Biennial Oscillation (QBO) in equatorial zonal wind, is an outstanding challenge in climate modeling.
		Although confined to the tropics, the QBO affects the circulation and the interannual variability of the entire stratosphere, parts of the mesosphere and possibly also of the troposphere.
		From this simulation it is inferred that a broad spectrum of atmospheric waves is necessary to generate the QBO in the model.
	www.mpg.de /forschungsergebnisse/wissVeroeffentlichungen/archivListenJahrbuch/2002/39/publZIM82.html (177 words)

	CEOP References (Site not responding. Last check: 2007-10-23)
		Kawamura, R., 1988: Quasi-biennial oscillation modes appearing in the tropical sea water temperature and 700 mb zonal wind.
		Meehl, G.A., 1993: A coupled air-sea biennial mechanism in the tropical Indian and Pacific region: role of the ocean.
		Shen, S. and K.-M. Lau, 1995: Biennial oscillation associated with the East Asian summer monsoon and tropical sea surface temperatures.
	www.joss.ucar.edu /ghp/references.html (280 words)

	[No title] (Site not responding. Last check: 2007-10-23)
		This model is used to study how the mean flow in the equatorial lower stratosphere would repond to forcing by a tropospheric wave spectrum with a significant amount of momentum flux at slow horizontal phase speeds.
		But the factors that control the period and amplitude of the oscillations, in the case of a continuous spectrum, seem to be quite different.
		Our results also suggest that mean rising motion in the tropics may play an important role in determining the vertical structure of the QBO near the tropopause.
	www.gfdl.noaa.gov /~gth/netscape/1990/rs9001.html (184 words)

	Dynamics of monsoon-induced biennial variability in ENSO
		The correlation suggests a biennial tendency in the surface wind in the western Pacific with respect to the thermocline variability in the eastern Pacific.
		The ENSO oscillation is therefore strongly damped as illustrated in Fig.
		In the model coupled system, the ENSO oscillation period is either 3-4 year or quasi-biennial depending on the strength of the monsoon-ENSO coupling.
	atmospheres.gsfc.nasa.gov /contact/work/tbo/tbogrl.html (2894 words)

	5.2 Quasi-Biennial Oscillation (Site not responding. Last check: 2007-10-23)
		The phase and magnitude of QBO are associated with the frequency of TCs in the Atlantic (Gray, 1984; Shapiro, 1989).
		The exact mechanism by which the QBO affects TCs in the troposphere is not clear.
		The oscillation signal of zonal wind is strongest at the layer between 30-50 hPa, but is virtually undetected at 100 hPa.
	www.nrlmry.navy.mil /~chu/chap3/se502.htm (115 words)

	Paul BEGLEY (Site not responding. Last check: 2007-10-23)
		The Quasi - Biennial Oscillation describes a shift of stratospheric winds above the equator between east and westerly winds.
		Within the tropical Atlantic, surface wind stress and sea surface temperatures fluctuate on a time -scale similar to the Quasi - Biennial Oscillation, and the correlation with El Nino are small (Tseng 1999*).
		In fact, it is generally agreed that the Quasi - Biennial Oscillation maintains its characteristics even in years of a strong El Nino (Zimmer, 1999).
	www.egs.uct.ac.za /~pbegley/QBO.html (163 words)

	Jahrbuch-CD der MPG 2003 - Sensitivity of the quasi-bienni
		The period of quasi-biennial oscillation (QBO) of equatorial stratospheric winds is mainly determined by the magnitude of upward momentum transport by equatorial waves and the intensity of the Brewer-Dobson circulation.
		The observed QBO period is an average of 28 months, but it can range from 24 to 30 months.
		A speedup of the oscillation from the control experiment value of 34 months to between 22 and 17 minths is observed, where easterly (westerly) phase duration decrease mostly at upper (lower) QBO levels.
	www.mpg.de /forschungsergebnisse/wissVeroeffentlichungen/archivListenJahrbuch/2003/39/publZIM59.html (330 words)

	The 10-12-year atmospheric oscillation
		The oscillation modulates the extratropical effect of the Quasi-Biennial Oscillation in winter and is in phase with the 11-year sunspot cycle.
		In January and February the correlations of a full time series of stratospheric quantities with the sun are smallest, although the basic pattern is the same as during the rest of the year.
		Labitzke, K., 1987: Sunspots, the QBO, and the stratospheric temperature in the north polar region.
	strat-www.met.fu-berlin.de /labitzke/tto/tto.html (344 words)

	Interannual Variability of the Tropical Atlantic Climate and Its Relations to El Nino (Site not responding. Last check: 2007-10-23)
		In the equatorial sector, the former approach identifies a dominant quasi-biennial oscillation with a period of 28~30 months.
		The oscillation exhibits features characteristic of equatorial coupled modes, and its correlation with ENSO is small.
		These results indicate that the imprint of ENSO onto this remote ocean region may not be systematic, and that the strength of the inter-basin connection varies from event to event.
	iri.columbia.edu /outreach/meeting/TWWS1999/Li_san/Li_San.htm (476 words)

	INTELLiCast: SUPER EL NINO
		The QBO reflects the fact that the winds in the stratosphere (at around 45 mb) over the equator in the Pacific alternately blow west and east in a cycle that averages about 28 months.
		In La Nina years with an easterly QBO and a quiet sun, the storm track is usually from the southwest to the mid-Atlantic which threatens heavy snows from the Midwest to the northeast.
		If the QBO changes phase in mid or late winter as seems likely, a split flow would be favored with strong southern branch storms lashing California and redeveloping near the Gulf coast and dumping very heavy rains and triggering severe weather in the southeast states.
	www.ibiblio.org /intergarden/permaculture/mailarchives/permanet.1/msg00108.html (2396 words)

	<center>El Niño-Southern Oscillation and the seasonal predictability of tropical cyclones</center>
		Beside the El Niño-Southern Oscillation, there is another global factor that appears to force changes in tropical cyclones: the stratospheric Quasi-Biennial Oscillation (QBO), an east-west oscillation of stratospheric winds that encircle the globe near the equator (Wallace 1973).
		As with the 1 December forecast, three of the predictors are for extrapolating the state of the QBO expected during September - zonal winds at 50 mb, 30 mb, and the vertical shear between the two layers.
		The QBO measures of 50 mb and 30 mb zonal winds and the vertical shear between the two levels through July are extrapolated two months forward to September.
	www.aoml.noaa.gov /hrd/Landsea/el_nino/index.html (9746 words)

	Other Factors Affecting Arctic Ozone Depletion - Arctic Ozone - [Meteorological Service of Canada - The Green Lane]
		This phenomenon is known as the quasi-biennial oscillation (QBO).
		When the QBO is in its westerly phase, polar stratospheric temperatures are generally lower, the poleward transport of ozone is reduced, and ozone depletion tends to be greater.
		In 1993, 1995, and 1997, for example, the QBO was in its westerly phase and large ozone losses were recorded in the Arctic.
	www.msc-smc.ec.gc.ca /education/arcticozone/other_e.cfm?sv_templateFormat=print (876 words)

	Is There a Quasi-Biennial Oscillation in Tropical Deep Convection? (Site not responding. Last check: 2007-10-23)
		We investigate the possibility that the stratospheric Quasi-Biennial Oscillation (QBO) modulates deep convection in the tropics.
		Interannual variations of outgoing longwave radiation (OLR) in the tropics during 1975-87 are compared with stratospheric zonal winds at Singapore (a measure of the QBO), and with the Tahiti - Darwin sea level pressure difference (the Souther Oscillation Index, or SOI).
		These results are not inconsistent with the hypothesis that deep convection may be enhanced in chronically cold areas when QBO westward shear exists in the lower stratosphere, and diminished during eastward shear.
	www.aos.wisc.edu /~mag/QBOConvectionAbstract.html (180 words)

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