Wat betreft de kans op een SSW in dec/jan is dit onderzoek van belang.Sebastiaan schreef: ↑08-08-2021 12:09https://twitter.com/JimSullivan92/statu ... 0586555399
The cooling beneath the surface across the equatorial Pacific has been impressive over the last 5 weeks...it's now cooler beneath the surface than last year at this time. With a +SOI favored for the foreseeable future, another La Nina winter seems increasingly likely.
Equal frequency of stratospheric sudden warmings in El Nino and La Nina winters.
Amy H. Butler ,Chaim Garfinkel, Darryn Waugh, Lorenzo
Polvani, and Margaret Hurwitz.
https://www.cpc.ncep.noaa.gov/products/ ... Butler.pdf
In vergelijking met de afgelopen winter 2020/2021 is het verschil in de komende winter 2021/2022 niet QBOW maar QBOE.
Wat dit verschil in het verleden heeft betekend is onderzocht met behulp van:" Zonal wind and precipitation fields for the period 1958–2016 are from the European Centre for Medium Range Weather Forecasting (ECMWF)." . https://acp.copernicus.org/articles/18/8227/2018/
Abstract
"Teleconnections between the Quasi Biennial Oscillation (QBO) and the Northern Hemisphere zonally averaged zonal winds, mean sea level pressure (mslp) and tropical precipitation are explored. The standard approach that defines the QBO using the equatorial zonal winds at a single pressure level is compared with the empirical orthogonal function approach that characterizes the vertical profile of the equatorial winds. Results are interpreted in terms of three potential routes of influence, referred to as the tropical, subtropical and polar routes. A novel technique is introduced to separate responses via the polar route that are associated with the stratospheric polar vortex, from the other two routes. A previously reported mslp response in January, with a pattern that resembles the positive phase of the North Atlantic Oscillation under QBO westerly conditions, is confirmed and found to be primarily associated with a QBO modulation of the stratospheric polar vortex. This mid-winter response is relatively insensitive to the exact height of the maximum QBO westerlies and a maximum positive response occurs with westerlies over a relatively deep range between 10 and 70 hPa. Two additional mslp responses are reported, in early winter (December) and late winter (February/March). In contrast to the January response the early and late winter responses show maximum sensitivity to the QBO winds at ∼ 20 and ∼ 70 hPa respectively, but are relatively insensitive to the QBO winds in between (∼ 50 hPa). The late winter response is centred over the North Pacific and is associated with QBO influence from the lowermost stratosphere at tropical/subtropical latitudes in the Pacific sector. The early winter response consists of anomalies over both the North Pacific and Europe, but the mechanism for this response is unclear. Increased precipitation occurs over the tropical western Pacific under westerly QBO conditions, particularly during boreal summer, with maximum sensitivity to the QBO winds at 70 hPa. The band of precipitation across the Pacific associated with the Inter-tropical Convergence Zone (ITCZ) shifts southward under QBO westerly conditions. The empirical orthogonal function (EOF)-based analysis suggests that this ITCZ precipitation response may be particularly sensitive to the vertical wind shear in the vicinity of 70 hPa and hence the tropical tropopause temperatures."
In de loop van november zal meer duidelijk worden hoe sterk de La Nina wordt en wat de stand is van de QBOE.