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

[Karel]

Verder herstel van de oostenwinden rond de evenaar op 30 hPa verwacht door het ECMWF model. Als de zomer maar lang genoeg duurt ........

[Karel]

Aandacht voor de ontwikkeling van de zonneactiviteitscyclus voor de mogelijke steun in de rug voor de komende winter in Noord West Europa.
https://www.rmets.org/sites/default/fil ... limate.pdf
Maximum en minimum onderscheid in:Solar forcing for CMIP6 (v3.2)Katja Matthes1,2 e.a.https://ora.ox.ac.uk/objects/uuid:606be ... al+article

[Karel]

Aanvullend nog de verwachte afwijkingen van de gemiddelde zeewatertemperaturen aan het begin van de winter 2020 vergeleken met 2019:
een compleet verschillend tegegesteld beeld in de oostelijke en westelijke Pacific. Ook in de Indische Oceaan tegengesteld beeld. Een steuntje in de rug voor de winter?

[Karel]

De verwachte zeewatertemperaturen voor de komende winter in de tropen. Een steuntje in de rug voor de komende winter door de kans op een negatieve NAO.Bronnen:https://www.google.com/url?sa=t&rct=j&q ... MbHPs3VbYZ en https://journals.ametsoc.org/jcli/artic ... of-La-Nina

[Sebastiaan]

Dank Karel!

https://www.netweather.tv/forum/topic/8 ... /#comments

1 - The first big area of note is how much the easterly QBO has descended between 3 hpa and 7 hpa in just the last few days since my last update. The last update only showed a tiny pale green mark in the corner. Now there's a whole zone of weak easterlies at all of these levels. This is really getting a move on but then looking at the rest of the chart at these high levels it seems the QBO does change very quickly above 10 hpa.

2 - The second region of note is what is happening between 10 hpa and 20 hpa. Notice how the weakest westerly colour is still expanding and has weakened enough to reveal the couple of weak easterly patches in the middle of this region. Maybe this easterly region that doesn't show up at this resolution as well as the one descending down from above will eventually merge into a new EQBO, resulting in a failure of the WQBO instead of the EQBO

3 - Overall this chart shows that the easterly anomaly has continued to weaken and westerlies are descending down to below 40 hpa on average now. For the sake of a possible return of the EQBO this process needs to continue to allow the westerlies at 30 hpa to descend

4a and 4b - Westerlies look to be becoming ever more dominant at 30 hpa and a clear strengthening is seen on this chart, so much so that the average wind speed is now comparable with normal WQBO winds from the last WQBO. I don't know what effect this will have on the atmosphere since the WQBO layer is so shallow and with easterlies below it too with a much deeper layer.

Next I will show both the QBO plot chart again as well as the monthly QBO plots showing all QBO phases based on stage within the cycle.
I've decided to make a prediction as to where I think July 2020 is going to feature on the right hand chart. I feel July is a weakened version of the westerlies plot graph in the top right corner near the word westerlies with weak easterlies both at the top and bottom so I feel July will be somewhere within the red circle with 07 in the middle of it as a weak westerly QBO.

As for August 2020 with some interesting recent developments with increasing signs of easterlies returning then I feel this WQBO is going to be a very short one like the last EQBO and also weak too like it and then we will possibly power up into a more normal EQBO after this strange QBO event we have had in recent months.

Another thing that backs up the building of easterlies from 20 hpa upwards is what is showing on the atmospheric charts I showed last time.

Focus on all the areas showing within the green circles I have drawn over these charts. Notice the increasing prevalence of the pale blue weak easterly regions taking over close to the equator combined with the weakening of westerlies between 3 hpa and 10 hpa. Looks like the EQBO could be building back up again ready to start a new EQBO cycle off again.

Maybe there is hope that the EQBO wasn't killed off after all and in fact it could be the WQBO that should have started to descend from 10 hpa at around this point of the year that will fail instead.

[Karel]

ECMWF berekent nog steeds meer oostenwind in de stratosfeer. Nog een paar maanden de tijd voor verdere intensivering oostenwinden.

[Paul]

Interessante ontwikkelingen, dank je Karel en Sebastiaan voor jullie berichten.

Over de noordelijke Pacific:

Knipsel2.PNG

Na 2013 telkens T+ anomalie daar. Geen toeval zachte winters in groot deel NH. Zie vooral 2014-2015 met sterk positieve PDO.

In combinatie met sterke La Nina mogelijk anders...

Negatieve IOD in de progs is een mooi signaal.
Ik vind wel dat de verre verwachtingen voor de aanloop van de winter van UKMO weinig goeds beloven.

[Sebastiaan]

https://agupubs.onlinelibrary.wiley.com ... 18JD029368
The Quasi‐Biennial Oscillation (QBO) is the dominant mode of interannual variability in the tropical stratosphere, with easterly and westerly zonal wind regimes alternating over a period of about 28 months. It appears to influence the Northern Hemisphere winter stratospheric polar vortex and atmospheric circulation near the Earth's surface. However, the short observational record makes unequivocal identification of these surface connections challenging. To overcome this, we use a multicentury control simulation of a climate model with a realistic, spontaneously generated QBO to examine teleconnections with extratropical winter surface pressure patterns. Using a 30‐hPa index of the QBO, we demonstrate that the observed teleconnection with the Arctic Oscillation (AO) is likely to be real, and a teleconnection with the North Atlantic Oscillation (NAO) is probable, but not certain. Simulated QBO‐AO teleconnections are robust, but appear weaker than in observations. Despite this, inconsistency with the observational record cannot be formally demonstrated. To assess the robustness of our results, we use an alternative measure of the QBO, which selects QBO phases with westerly or easterly winds extending over a wider range of altitudes than phases selected by the single‐level index. We find increased strength and significance for both the AO and NAO responses, and better reproduction of the observed surface teleconnection patterns. Further, this QBO metric reveals that the simulated AO response is indeed likely to be weaker than observed. We conclude that the QBO can potentially provide another source of skill for Northern Hemisphere winter prediction, if its surface teleconnections can be accurately simulated.

[Sebastiaan]

https://agupubs.onlinelibrary.wiley.com ... 20GL087766
Simple models of wave‐mean flow interaction in the Northern Hemisphere winter stratosphere suggest the existence of subseasonal vacillations in the strength of the polar vortex. Here, we define a sinusoidal fit to the daily deseasonalized stratospheric wind. A suitable fixed period and amplitude for the sine waves is identified. Their mean value, equivalent to polar vortex strength, and phase, equivalent to the timing of sudden stratospheric warmings during winter, varies from year to year. These vacillations explain much of the subseasonal and interannual variability in the monthly mean vortex strength and, consistent with wave‐mean flow interaction theory, their amplitude correlates positively with the magnitude of winter mean planetary wave driving. Furthermore, they allow skillful prediction of the vortex strength one month ahead. Identifying and understanding this subseasonal variability has potential implications for winter seasonal forecasts, as the December–February mean behavior may miss important subseasonal events.

[Sebastiaan]

2.51 -3.20 -4.36 -5.03 -4.86 -2.78 0.34
QBO positief in juli.