Je ziet dan op de 500 hPa-kaarten van WetterZentrale ook meer groene en gele kleuren, i.p.v. donkerblauw en paars. Zie https://www.weerwoord.be/m/1754659
Stratosfeer winter 2020/2021
Re: Stratosfeer winter 2020/2021
Re: Stratosfeer winter 2020/2021
Niet best : {
CRe: Stratosfeer winter 2020/2021
Blauw van de kou niet gewenst in dit geval.
Re: Stratosfeer winter 2020/2021
Ik kijk ook naar blauw. Maar dan van de oostenwinden die in de stratosfeer op de kaart verschijnen. Op 2 januari berekent ECMWF oper 1200u nog maar uitsluitend de kenmerkende subtropische straalstroom. Van het aardoppervlak tot boven 1hpa zeer lage zonale snelheden ten noorden van 50N en de opwarming in rood gaat dan nog verder. Blauwe oostenwinden verschijnen in de stratosfeer in het hoge noorden.
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Sebastiaan
- Berichten: 12288
- Lid geworden op: 31-12-1977
Re: Stratosfeer winter 2020/2021
Ja, EC-run ziet er erg goed uit. Nog een paar dagen geduld.
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Sebastiaan
- Berichten: 12288
- Lid geworden op: 31-12-1977
Re: Stratosfeer winter 2020/2021
ec46 toont ssw, geen 'gewenste' temperatuur repercussies
Je hebt niet voldoende permissies om de bijlagen van dit bericht te bekijken.
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Sebastiaan
- Berichten: 12288
- Lid geworden op: 31-12-1977
Re: Stratosfeer winter 2020/2021
In 2018 hadden we een SSW. Natuurlijk verschijnen er dan wetenschappelijke artikelen om het natuurwonder te analyseren.
Ik wil uit een van deze publicaties iets melden.
http://agupubs.onlinelibrary.wiley.com/ ... 18GL081091
Predicting Sudden Stratospheric Warming 2018 and Its Climate Impacts With a Multimodel Ensemble
Laten we eerst eens kijken naar de samenvatting in eenvoudig Engels.
Predicting climate anomalies more than 2 weeks ahead remains a challenging task. However, there are periods when climate is more predictable. In particular, it is known that in the wintertime Northern Hemisphere midlatitudes, climate may be more predictable during several weeks following sudden stratospheric warmings (SSWs), when a cold stratospheric polar vortex suddenly breaks and the stratosphere warms. In this article we evaluate quality of monthly forecasts by several up?to?date forecast systems during a sudden stratospheric warming observed in February 2018 focusing both on predictability of the stratospheric anomalies and on predictability of their surface impacts. We find that models predicted enhanced probability of sudden stratospheric warming at least 11 days before the observed event. Four days before the event it was forecast by all models with a very high certainty. We further show that successful prediction of the SSW required correct forecasting of anticyclonic anomaly over Ural and associated upward propagation of planetary?scale atmospheric waves. The observed cold anomaly across Eurasia in February 2018 was predicted more than 2 weeks ahead although at this lead time the predictability was more likely associated with persistence of tropospheric anomalies in the forecast, with smaller downward influence of the stratospheric anomalies.
De auteurs onderzoeken wanneer de verschillende modellen de SSW van 2018 in de smiezen kregen. De modellen zagen de toenemende kans op een SSW minstens 11 dagen van te voren. Vier dagen voor dat de SSW daadwerkelijk plaatsvindt, zien alle modellen de gebeurtenis. Belangrijk was het goed voorspellen waar het hogedrukgebied boven de Oeral lag. De koude zat meer dan twee weken van te voren in de modellen en dat had waarschijnlijk te maken met de invloed van de troposfeer.
Een aantal opmerkingen van de auteurs:
Thus, the correlations field indicates that stronger SLP is southern Ural is associated with weaker stratospheric winds and suggests that errors in the location of the Ural high turn out to be crucial for forecasting SSW.
Voor een zwakkere strato poolwervel is het van belang dat de luchtdruk in het zuiden van de Oeral hoog is. Verschillen in de positionering van het hogedrukgbied leiden tot verschillende uitkomsten van de sterkte van de strato poolwervel. Paul heeft daar al eens opgewezen.
Turning to the forecast from 8 February 2018 when the multimodel ensemble successfully predicted SSW, one can see that the ensemble captures the observed downward propagation of the anomalies as well as their long duration in the lower stratosphere during the SSW recovery phase.
Op 8 februari voorspellen de modellen een SSW met daarbij de downwelling [afzakken] en hun langdurige invloed.
Here we show that skillful forecasts are possible as soon as the models start to predict SSW, or at least 4 days before the onset date. We have also shown that the limiting factor in predicting the SSW itself at lead time of about 10 days was an underestimation of the magnitude of wave activity propagation to the stratosphere linked in turn to errors in the location of an Ural high.
Betekenisvolle verwachtingen worden mogelijk zodra de SSW binnen een periode van 4 dagen komt. De verwachting van de SSW wordt bemoeilijkt door de fouten in de berekeningen waar het Oeralhoog ligt.
Wat betekent dat voor de mogelijke (!) SSW van 2021. We zien dat de SSW in zicht komt. Zekerheid is er echter nog niet. Laten we zeggen 5 januari. Dat betekent dat we pas in het nieuwe jaar de eerste impact van de SSW in de stratosfeer. In 2018 onderschatte de modellen de impact van de SSW op neushoogte. De auteurs stellen dat dit mogelijk te maken heeft met de invloed van de MJO.
Ik wil uit een van deze publicaties iets melden.
http://agupubs.onlinelibrary.wiley.com/ ... 18GL081091
Predicting Sudden Stratospheric Warming 2018 and Its Climate Impacts With a Multimodel Ensemble
Laten we eerst eens kijken naar de samenvatting in eenvoudig Engels.
Predicting climate anomalies more than 2 weeks ahead remains a challenging task. However, there are periods when climate is more predictable. In particular, it is known that in the wintertime Northern Hemisphere midlatitudes, climate may be more predictable during several weeks following sudden stratospheric warmings (SSWs), when a cold stratospheric polar vortex suddenly breaks and the stratosphere warms. In this article we evaluate quality of monthly forecasts by several up?to?date forecast systems during a sudden stratospheric warming observed in February 2018 focusing both on predictability of the stratospheric anomalies and on predictability of their surface impacts. We find that models predicted enhanced probability of sudden stratospheric warming at least 11 days before the observed event. Four days before the event it was forecast by all models with a very high certainty. We further show that successful prediction of the SSW required correct forecasting of anticyclonic anomaly over Ural and associated upward propagation of planetary?scale atmospheric waves. The observed cold anomaly across Eurasia in February 2018 was predicted more than 2 weeks ahead although at this lead time the predictability was more likely associated with persistence of tropospheric anomalies in the forecast, with smaller downward influence of the stratospheric anomalies.
De auteurs onderzoeken wanneer de verschillende modellen de SSW van 2018 in de smiezen kregen. De modellen zagen de toenemende kans op een SSW minstens 11 dagen van te voren. Vier dagen voor dat de SSW daadwerkelijk plaatsvindt, zien alle modellen de gebeurtenis. Belangrijk was het goed voorspellen waar het hogedrukgebied boven de Oeral lag. De koude zat meer dan twee weken van te voren in de modellen en dat had waarschijnlijk te maken met de invloed van de troposfeer.
Een aantal opmerkingen van de auteurs:
Thus, the correlations field indicates that stronger SLP is southern Ural is associated with weaker stratospheric winds and suggests that errors in the location of the Ural high turn out to be crucial for forecasting SSW.
Voor een zwakkere strato poolwervel is het van belang dat de luchtdruk in het zuiden van de Oeral hoog is. Verschillen in de positionering van het hogedrukgbied leiden tot verschillende uitkomsten van de sterkte van de strato poolwervel. Paul heeft daar al eens opgewezen.
Turning to the forecast from 8 February 2018 when the multimodel ensemble successfully predicted SSW, one can see that the ensemble captures the observed downward propagation of the anomalies as well as their long duration in the lower stratosphere during the SSW recovery phase.
Op 8 februari voorspellen de modellen een SSW met daarbij de downwelling [afzakken] en hun langdurige invloed.
Here we show that skillful forecasts are possible as soon as the models start to predict SSW, or at least 4 days before the onset date. We have also shown that the limiting factor in predicting the SSW itself at lead time of about 10 days was an underestimation of the magnitude of wave activity propagation to the stratosphere linked in turn to errors in the location of an Ural high.
Betekenisvolle verwachtingen worden mogelijk zodra de SSW binnen een periode van 4 dagen komt. De verwachting van de SSW wordt bemoeilijkt door de fouten in de berekeningen waar het Oeralhoog ligt.
Wat betekent dat voor de mogelijke (!) SSW van 2021. We zien dat de SSW in zicht komt. Zekerheid is er echter nog niet. Laten we zeggen 5 januari. Dat betekent dat we pas in het nieuwe jaar de eerste impact van de SSW in de stratosfeer. In 2018 onderschatte de modellen de impact van de SSW op neushoogte. De auteurs stellen dat dit mogelijk te maken heeft met de invloed van de MJO.
Re: Stratosfeer winter 2020/2021
SSW koppeling stratosfeer/troposfeer in het GFS oper model in zicht begin jan 2021, Op 11/12 januari ziet het er prima uit.
De ontwikkeling in de troposfeer is in ieder geval gunstig in ECMWF berekeningen van deze ochtend voor eerst Europese blokkade en daarna NAO-.
Bronnen:
https://www.tropicaltidbits.com/analysi ... hem_33.png
https://stratobserve.com/anom_ts_diags
De ontwikkeling in de troposfeer is in ieder geval gunstig in ECMWF berekeningen van deze ochtend voor eerst Europese blokkade en daarna NAO-.
Bronnen:
https://www.tropicaltidbits.com/analysi ... hem_33.png
https://stratobserve.com/anom_ts_diags
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Sebastiaan
- Berichten: 12288
- Lid geworden op: 31-12-1977
Re: Stratosfeer winter 2020/2021
Even without a major sudden warming event (defined at 10 hPa) the lower stratospheric vortex is heading toward record-weak territory - opposite to this time last year! This will favour Greenland blocking regimes.
http://agupubs.onlinelibrary.wiley.com/ ... 19GL085592
http://rmets.onlinelibrary.wiley.com/do ... 02/qj.3280
Iets om over na te denken ivm discussie zien we in GFS effecten SSW. Hoe ik de tweet lees, komt het effect (meer nadruk op GL hoog) niet zozeer als effect van de SSW (negatieve wind def 60N, 10 hPa).
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Stratosphere–troposphere coupling is often viewed from the perspective of the annular modes and their dynamics. Despite the obvious benefits of this approach, recent work has emphasised the greater tropospheric sensitivity to stratospheric variability in the Atlantic basin than in the Pacific basin. In this study, a new approach to understanding stratosphere–troposphere coupling is proposed, with a focus on the influence of the stratospheric state on North Atlantic weather regimes (during extended winter, November to March). The influence of the strength of the lower?stratospheric vortex on four commonly used tropospheric weather regimes is quantified. The negative phase of the North Atlantic Oscillation is most sensitive to the stratospheric state, occurring on 33% of days following weak vortex conditions but on only 5% of days following strong vortex conditions. An opposite and slightly weaker sensitivity is found for the positive phase of the North Atlantic Oscillation and the Atlantic Ridge regime. For the North Atlantic Oscillation regimes, stratospheric conditions change both the probability of remaining in each regime and the probability of transitioning to that regime from others. A logistic regression model is developed to further quantify the sensitivity of tropospheric weather regimes to the lower stratospheric state. The logistic regression model predicts an increase of 40–60% in the probability of transition to the negative phase of the North Atlantic Oscillation for a one standard deviation reduction in the strength of the stratospheric vortex. Similarly it predicts a 10–30% increase in the probability of transition to the positive phase of the North Atlantic Oscillation for a one standard deviation increase in the strength of the stratospheric vortex. The stratosphere–troposphere coupling in the European Centre for Medium?range Weather Forecasts Integrated Forecasting System model is found to be consistent with the re?analysis data by fitting the same logistic regression model.
Abstract
The impact of the Arctic stratospheric polar vortex on persistent weather regimes over North America is so far underexplored. Here we show the relationship between four wintertime North American weather regimes and the stratospheric vortex strength using reanalysis data. We find that the strength of the vortex significantly affects the behavior of the regimes. While a regime associated with Greenland blocking is strongly favored following weak vortex events, it is not the primary regime associated with a widespread, elevated risk of extreme cold in North America. Instead, we find that the regime most strongly associated with widespread extremely cold weather does not show a strong dependency on the strength of the lower stratospheric zonal mean zonal winds. We also suggest that stratospheric vortex morphology may be particularly important for cold air outbreaks during this regime.
http://agupubs.onlinelibrary.wiley.com/ ... 19GL085592
http://rmets.onlinelibrary.wiley.com/do ... 02/qj.3280
Iets om over na te denken ivm discussie zien we in GFS effecten SSW. Hoe ik de tweet lees, komt het effect (meer nadruk op GL hoog) niet zozeer als effect van de SSW (negatieve wind def 60N, 10 hPa).
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Stratosphere–troposphere coupling is often viewed from the perspective of the annular modes and their dynamics. Despite the obvious benefits of this approach, recent work has emphasised the greater tropospheric sensitivity to stratospheric variability in the Atlantic basin than in the Pacific basin. In this study, a new approach to understanding stratosphere–troposphere coupling is proposed, with a focus on the influence of the stratospheric state on North Atlantic weather regimes (during extended winter, November to March). The influence of the strength of the lower?stratospheric vortex on four commonly used tropospheric weather regimes is quantified. The negative phase of the North Atlantic Oscillation is most sensitive to the stratospheric state, occurring on 33% of days following weak vortex conditions but on only 5% of days following strong vortex conditions. An opposite and slightly weaker sensitivity is found for the positive phase of the North Atlantic Oscillation and the Atlantic Ridge regime. For the North Atlantic Oscillation regimes, stratospheric conditions change both the probability of remaining in each regime and the probability of transitioning to that regime from others. A logistic regression model is developed to further quantify the sensitivity of tropospheric weather regimes to the lower stratospheric state. The logistic regression model predicts an increase of 40–60% in the probability of transition to the negative phase of the North Atlantic Oscillation for a one standard deviation reduction in the strength of the stratospheric vortex. Similarly it predicts a 10–30% increase in the probability of transition to the positive phase of the North Atlantic Oscillation for a one standard deviation increase in the strength of the stratospheric vortex. The stratosphere–troposphere coupling in the European Centre for Medium?range Weather Forecasts Integrated Forecasting System model is found to be consistent with the re?analysis data by fitting the same logistic regression model.
Abstract
The impact of the Arctic stratospheric polar vortex on persistent weather regimes over North America is so far underexplored. Here we show the relationship between four wintertime North American weather regimes and the stratospheric vortex strength using reanalysis data. We find that the strength of the vortex significantly affects the behavior of the regimes. While a regime associated with Greenland blocking is strongly favored following weak vortex events, it is not the primary regime associated with a widespread, elevated risk of extreme cold in North America. Instead, we find that the regime most strongly associated with widespread extremely cold weather does not show a strong dependency on the strength of the lower stratospheric zonal mean zonal winds. We also suggest that stratospheric vortex morphology may be particularly important for cold air outbreaks during this regime.
Je hebt niet voldoende permissies om de bijlagen van dit bericht te bekijken.