Ontwikkeling van de QBO, zonneactiviteit, ENSO, MJO en de winter 2020/2021

Alles wat betrekking heeft op het buitenlands weer. Tropische stormen, orkanen, etc.
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Karel
Berichten: 3189
Lid geworden op: 31-07-1978

Re: Ontwikkeling van de QBO, zonneactiviteit, ENSO, MJO en de winter 2020/2021

Bericht door Karel » 04-06-2020 16:28

Kern oostenwinden in de stratosfeer boven de evenaar OP 50 hPa (15 m/s) volgens geo berlin :https://www.geo.fu-berlin.de/en/met/ag/ ... index.html en ECMWF.

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Karel
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Re: Ontwikkeling van de QBO, zonneactiviteit, ENSO, MJO en de winter 2020/2021

Bericht door Karel » 07-06-2020 08:51

Versnelde afdaling van de QBO east ingezet.

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Karel
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Re: Ontwikkeling van de QBO, zonneactiviteit, ENSO, MJO en de winter 2020/2021

Bericht door Karel » 15-06-2020 16:08

De ontwikkeling van de QBO is dit jaar evenals in 1959-1960, 2010-2011 en 2015-2016 afwijkend van het gemiddelde beeld van de QBO na 1953.
De QBO wordt bepaald uit het gemiddelde van de windsnelheid tussen 2,5 S en 2,5 N op een niveau van 40hPa.http://oceanrep.geomar.de/47636/1/acp-20-6541-2020.pdf

De zone met de grootste oostenwind ging in ca twee weken (24 april - 12 mei) van 10 hPa (31km hoogte) naar 50 hPa (20 km hoogte). Normaal is een daalsnelheid van de zone met de hoogste oostelijke windsnelheid 1 km per maand!
De QBO is nu nog in de oostelijke fase (QBOeast). De komende maanden is het afwachten of de overheersende oostenwind in de tropen tussen 40hPa en 1010hPa stand houdt, Er is sinds midden mei sprake van een status quo.

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Sebastiaan
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Re: Ontwikkeling van de QBO, zonneactiviteit, ENSO, MJO en de winter 2020/2021

Bericht door Sebastiaan » 22-06-2020 19:10

https://rmets.onlinelibrary.wiley.com/d ... 38.twitter
Two recent occurrences in February 2018 and January 2019 of a dynamic split in the Northern Hemisphere stratospheric polar vortex are compared in terms of their evolution and predictability. The 2018 split vortex was associated with primarily wavenumber‐2 wave forcing that was not well predicted more than 7‐10 days ahead of time, and was followed by persistent coupling to the surface with strong weather impacts. In 2019 the vortex was first displaced by slow wavenumber‐1 amplification into the stratosphere, which was predictable at longer lead times, and then split; the surface impacts following the event were weaker. Here we examine the role of large‐scale climate influences, such as the phase of the El Niño‐Southern Oscillation, the Quasi‐biennial Oscillation and Madden‐Julian Oscillation, on the wave forcing, surface impacts, and predictability of these two events. Linkages between the forecast error in the stratospheric polar vortex winds with the forecast error in the Quasi‐biennial Oscillation and Madden‐Julian Oscillation are examined.
Laatst gewijzigd door Sebastiaan op 23-06-2020 10:31, 1 keer totaal gewijzigd.

Sebastiaan
Berichten: 12244
Lid geworden op: 31-12-1977

Re: Ontwikkeling van de QBO, zonneactiviteit, ENSO, MJO en de winter 2020/2021

Bericht door Sebastiaan » 23-06-2020 08:55

https://www.essoar.org/doi/10.1002/esso ... 8M.twitter
The quasi-biennial oscillation (QBO) is a repeating cycle of tropical stratosphere winds reversing direction from eastward to westward roughly every 14 months. Discovered independently by British and American scientists the QBO continued undisturbed for 27 cycles from 1953 until February 2016 when a westward jet unexpectedly formed in the lower stratosphere during the eastward phase. This disruption is attributed to unusually high wave momentum fluxes from the Northern Hemisphere. A second, similar, QBO disruption occurred during the 2019/2020 northern winter though this time the Arctic polar vortex was exceptionally strong and wave fluxes weak. Here we show that this latest disruption to the regular QBO cycling was twice as strong as that seen in 2016 and resulted from horizontal momentum transport from the Southern Hemisphere. The disruption began in September 2019 when there was a rare Southern Hemisphere sudden stratospheric warming followed by abnormal conditions in the stratosphere with the smallest ozone hole since its discovery and enhanced equatorward momentum fluxes. In both disruptions the normal downward progression of the QBO halts and the eastward shear zone above the disruption moves upward assisted by stronger tropical upwelling during the boreal winter. Results from the two disruptions provide compelling evidence of a fundamental change in our understanding of the dynamics of the QBO with extra-tropical influences more significant than previously thought. In turn, this implies a less predictable QBO. Furthermore, the expected climate response of the mechanism we have identified suggests that reoccurring QBO disruptions are consistent with an emerging signal of climate change weakening QBO amplitudes as predicted by models.

Karel
Berichten: 3189
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Re: Ontwikkeling van de QBO, zonneactiviteit, ENSO, MJO en de winter 2020/2021

Bericht door Karel » 23-06-2020 12:04

Bedankt Sebastiaan voor de achtergrondinformatie over de bijzondere QBO dit jaar.

Aanvullend over de SSW's van 2018 en 2019 en de relatie met de MJO::https://rmets.onlinelibrary.wiley.com/a ... upInfo.pdf

Overigens ander onderzoek geeft aan dat Europa er slecht afkomt als het gaat om de invloed van SSW's op de voorspelbaarheid van het weerpatroon. Bij een sterke vortex gaat het wel erg goed.

https://agupubs.onlinelibrary.wiley.com ... 96.BRIDGE1 en
https://www.researchgate.net/profile/Da ... upling.pdf
met de quote:
"Overall, a strong reduction in forecast error and an increase in skill at lead times of 3–4 weeks can be observed over Russia, the United States, and the Middle East after weak vortex events, but not for Europe. For strong vortex events, the increase in predictability is overall less pronounced in these regions, but Europe tends to be better predicted than after weak vortex events."

Overigens is als naar de NAO alleen wordt gekeken is er meer lijn te vinden:https://rmets.onlinelibrary.wiley.com/d ... 02/asl.598



Sebastiaan
Berichten: 12244
Lid geworden op: 31-12-1977

Re: Ontwikkeling van de QBO, zonneactiviteit, ENSO, MJO en de winter 2020/2021

Bericht door Sebastiaan » 08-07-2020 09:20

Abstract
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There is an observed relationship linking Arctic sea ice conditions in autumn to mid-latitude weather the following winter. Of interest in this study is a hypothesized stratospheric pathway whereby reduced sea ice in the Barents and Kara seas enhances upward wave activity and wave-breaking in the stratosphere, leading to a weakening of the polar vortex and a transition of the North Atlantic Oscillation (NAO) to its negative phase. The Causal Effect Networks (CEN) framework is used to explore the stratospheric pathway between late autumn Barents–Kara sea ice and the February NAO, focusing on its seasonal evolution, timescale dependence, and robustness. Results indicate that the pathway is statistically detectable and has been relatively active over the 39-year observational period used here, explaining approximately 26 % of the interannual variability in the February NAO. However, a bootstrap-based resampling test reveals that the pathway is highly intermittent: the full stratospheric pathway appears in only 16 % of the sample populations derived from observations, with individual causal linkages ranging from 46 % to 84 % in occurrence rates. The pathway's intermittency is consistent with the weak signal-to-noise ratio of the atmospheric response to Arctic sea ice variability in modelling experiments and suggests that Arctic–mid-latitude teleconnections might be favoured in certain background states. On shorter timescales, the CEN detects two-way interactions between Barents–Kara sea ice and the mid-latitude circulation that indicate a role for synoptic variability associated with blocking over the Urals region and moist air intrusions from the Euro-Atlantic sector. This synoptic variability has the potential to interfere with the stratospheric pathway, thereby contributing to its intermittency. This study helps quantify the robustness of causal linkages within the stratospheric pathway, and provides insight into which linkages are most subject to sampling issues within the relatively short observational record. Overall, the results should help guide the analysis and design of ensemble modelling experiments required to improve physical understanding of Arctic–mid-latitude teleconnections.

How to cite.
Siew, P. Y. F., Li, C., Sobolowski, S. P., and King, M. P.: Intermittency of Arctic–mid-latitude teleconnections: stratospheric pathway between autumn sea ice and the winter North Atlantic Oscillation, Weather Clim. Dynam., 1, 261–275, https://doi.org/10.5194/wcd-1-261-2020, 2020. https://wcd.copernicus.org/articles/1/261/2020/

Karel
Berichten: 3189
Lid geworden op: 31-07-1978

Re: Ontwikkeling van de QBO, zonneactiviteit, ENSO, MJO en de winter 2020/2021

Bericht door Karel » 10-07-2020 20:56

De komende herfst weinig ijs en hoge watertemperaturen in de buurt van Nova Zembla gecombineerd met een La Niña. Wat dat betekent even toetsen met voorgaand artikel.
Ook is het spannend wat betreft de QBO. Op 10 hPa is enig herstel van de oostenwinden zichtbaar de afgelopen 10 dagen. Ook het ECMWF-model gaat in de richting van meer oostenwinden op 10 hPa en daaronder de komende dagen in de tropen.

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