Stratosfeer winter 2021/2022

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

Re: Stratosfeer winter 2021/2022

Bericht door Sebastiaan » 15-06-2022 15:56

Ja, datzelfde zien we bij Groenland. Dan spreken vaak mensen van Groenlandhoog. Terwijl dat niet zo is.

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

Re: Stratosfeer winter 2021/2022

Bericht door Sebastiaan » 21-06-2022 15:37

https://wcd.copernicus.org/articles/3/659/2022/
Natural variations in the strength of the northern stratospheric polar vortex, so-called polar vortex events, help to improve subseasonal-to-seasonal (S2S) predictions of winter climate. Past research on polar vortex events has been largely focused on sudden stratospheric warming events (SSWs), a class of relatively strong weakenings of the polar vortex. Commonly, SSWs are defined when the polar vortex reverses its climatological wintertime westerly wind direction. In this study, however, we use an alternative definition, based on the weighted time-integrated upward wave activity flux at the lower stratosphere. We use a long control simulation with a stratosphere-resolving model and the ERA5 reanalysis to compare various aspects of the wave activity definition with common SSWs over the Arctic. About half of the wave events are identical to common SSWs. However, there exist several advantages for defining stratospheric weak extremes based on wave events rather than using the common SSW definition: the wave activity flux definition captures with one criterion a variety of different event types, detects strong SSWs and strong final warming events, avoids weak SSWs that have little surface impact, and potentially lengthens the prediction horizon of the surface response. We therefore conclude that the wave driving represents a useful early indicator for stratospheric polar vortex events, which exploits the stratospheric potential for creating predictable surface signals better than common SSWs.

Gerben
Berichten: 16631
Lid geworden op: 08-09-2013

Re: Stratosfeer winter 2021/2022

Bericht door Gerben » 15-07-2022 15:25

Sebastiaan schreef:
15-06-2022 15:56
Ja, datzelfde zien we bij Groenland. Dan spreken vaak mensen van Groenlandhoog. Terwijl dat niet zo is.
Weet ik maar dat waren wel hoge barometerstanden....nu al een tijdje zo'n 50 hPa lager
Je hebt niet voldoende permissies om de bijlagen van dit bericht te bekijken.

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

Re: Stratosfeer winter 2021/2022

Bericht door Sebastiaan » 30-07-2022 15:50

Modelletjes tonen zwakke stratosfeer in december.
Je hebt niet voldoende permissies om de bijlagen van dit bericht te bekijken.

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

Re: Stratosfeer winter 2021/2022

Bericht door Karel » 03-08-2022 20:45

Sebastiaan schreef:
21-06-2022 15:37
https://wcd.copernicus.org/articles/3/659/2022/
Natural variations in the strength of the northern stratospheric polar vortex, so-called polar vortex events, help to improve subseasonal-to-seasonal (S2S) predictions of winter climate. Past research on polar vortex events has been largely focused on sudden stratospheric warming events (SSWs), a class of relatively strong weakenings of the polar vortex. Commonly, SSWs are defined when the polar vortex reverses its climatological wintertime westerly wind direction. In this study, however, we use an alternative definition, based on the weighted time-integrated upward wave activity flux at the lower stratosphere. We use a long control simulation with a stratosphere-resolving model and the ERA5 reanalysis to compare various aspects of the wave activity definition with common SSWs over the Arctic. About half of the wave events are identical to common SSWs. However, there exist several advantages for defining stratospheric weak extremes based on wave events rather than using the common SSW definition: the wave activity flux definition captures with one criterion a variety of different event types, detects strong SSWs and strong final warming events, avoids weak SSWs that have little surface impact, and potentially lengthens the prediction horizon of the surface response. We therefore conclude that the wave driving represents a useful early indicator for stratospheric polar vortex events, which exploits the stratospheric potential for creating predictable surface signals better than common SSWs.
Bedankt Sebastiaan. Zeer interessant onderzoek. De zgn wave flux op 100 hPa (PWD's en NWD's) speelt in dit onderzoek een belangrijke rol in de troposfeer/stratosfeer/troposfeer interactie. Zowel modelberekeningen als historische voorbeelden worden getoond. Beeld is zeer illustratief.

Afbeelding

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

Re: Stratosfeer winter 2021/2022

Bericht door Sebastiaan » 26-08-2022 14:09

https://rmets.onlinelibrary.wiley.com/d ... 2/wea.3868

Het is zover. Op naar de winter van 2023.
Je hebt niet voldoende permissies om de bijlagen van dit bericht te bekijken.

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