Stratosfeer winter 2019/2020

Discussieer mee over alles wat met het weer, weerkunde en de wereld eromheen te maken heeft
Paul
Berichten: 511
Lid geworden op: 01-01-1980

Re: Stratosfeer winter 2019/2020

Bericht door Paul » 04-03-2020 13:13

Ik dacht misschien krijgen we net zo een prachtige maart als in 1990, na de record hoge AO van dat jaar. Maar het ziet er niet naar uit, kijkende naar de weerkaarten.

Er is een belangrijk verschil met 1990. In dat jaar hadden we een behoorlijke verzwakking van de SPV in februari. Dit jaar juist een versterking.

Een andere rampwinter met een prachtige lente, 2007, had zelfs een SSW eind februari.
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Karel
Berichten: 2484
Lid geworden op: 31-07-1978

Re: Stratosfeer winter 2019/2020

Bericht door Karel » 04-03-2020 14:37

Paul, Het IOD-patroon in de Indische Oceaan in de afgelopen maanden september/oktober/november was inderdaad bijzonder en blijkbaar bepalend voor het winterweer op het Noordelijk Halfrond. Interessant want tot nu toe was de aandacht gericht op de IOD-invloed op Oost-Afrika en Australië.
https://www.metsoc.jp/default/wp-conten ... 3_Saji.pdf

Sinds 1960 is de frequentie van positieve IOD's flink toegenomen.http://ocp.ldeo.columbia.edu/res/div/oc ... l2008a.pdf
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De verwachte ontwikkeling door BOM in de komende maanden is hoopgevend.
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Sebastiaan
Berichten: 5740
Lid geworden op: 01-01-1978

Re: Stratosfeer winter 2019/2020

Bericht door Sebastiaan » 04-03-2020 16:41

Dank Karel. Opvallend dat het sinds de jaren zestig de IOD vaker positief was.

Interessante studie over ENSO en IOD.

https://www.clim-past-discuss.net/cp-2020-22/

Received: 13 Feb 2020 – Accepted for review: 02 Mar 2020 – Discussion started: 04 Mar 2020
Abstract. The dominant modes of climate variability on interannual timescales in the tropical Indian Ocean are the El Niño Southern Oscillation (ENSO) and the Indian Ocean Dipole. El Niño events have occurred more frequently during recent decades and it has been suggested that an asymmetric ENSO teleconnection (warming during El Niño events is stronger than cooling during La Niña events) caused the pronounced warming of the western Indian Ocean. In this study, we test this hypothesis using coral Sr / Ca records from the central Indian Ocean (Chagos Archipelago) to reconstruct past sea surface temperatures (SST) in time windows from the Maunder Minimum to the present. Three sub-fossil massive Porites corals were dated to the 17–18th century (one sample) and 19–20th century (two samples), and were compared with a published, modern coral Sr / Ca record from the same site. All corals were sub-sampled at a monthly resolution for Sr / Ca measurements, which were measured using a simultaneous ICP-OES. All four coral records show typical ENSO periodicities, suggesting that the ENSO-SST teleconnection in the central Indian Ocean was stationary since the 17th century. To determine the symmetry of ENSO events, we compiled composite records of positive and negative ENSO-driven SST anomaly events. We find similar magnitudes of warm and cold anomalies indicating a symmetric ENSO response in the tropical Indian Ocean. This suggests that ENSO is not the main driver of central Indian Ocean warming.

How to cite: Leupold, M., Pfeiffer, M., Watanabe, T. K., Reuning, L., Garbe-Schönberg, D., Shen, C.-C., and Brummer, G.-J. A.: ENSO and internal sea surface temperature variability in the tropical Indian Ocean since the Maunder Minimum, Clim. Past Discuss., https://doi.org/10.5194/cp-2020-22, in review, 2020.

Sebastiaan
Berichten: 5740
Lid geworden op: 01-01-1978

Re: Stratosfeer winter 2019/2020

Bericht door Sebastiaan » 04-03-2020 16:44

6 Conclusions
355 We have shown that the ENSO-SST relationship in the central Indian Ocean was stationary since the 17th century. All four
coral records showed typical ENSO periodicities, but variations in the frequency of ENSO events and in intensity. Whereas
both El Niño and La Niña events occur more often in modern periods (inferred from satellite and coral records) than in the 17-
18th century, El Niño events were more extreme in the 17-18th century relative to ENSO signals in modern coral (1965-1995)
and satellite (1981-2018) records. El Niño events cause average positive anomalies of 2.2 ± 0.2°C during the 17-18th century
360 and 1.3 ± 0.1°C during the 19-20th century, while La Niña events cause average negative anomalies of -1.5 ± 0.3°C during the
17-18th century and -1.6 ± 0.2°C during the 19-20th century in the central Indian Ocean. However, not all cooling events are
related to La Niña events, but also to processes internal to the Indian Ocean causing negative anomalies of -1.5 ± 0.4°C during
the 19-20th century. The magnitudes of El Niño and La Niña events during the last century are comparable indicating a
symmetric ENSO teleconnection. An asymmetric ENSO teleconnection being the cause for the overall warming of the central,
365 tropical Indian Ocean appears therefore unlikely. However, we suggest compiling composite records of negative and positive
SST anomaly events from sub-fossil corals to further test the hypothesis of an asymmetric ENSO teleconnection in the western
Indian Ocean.

Paul
Berichten: 511
Lid geworden op: 01-01-1980

Re: Stratosfeer winter 2019/2020

Bericht door Paul » 05-03-2020 12:54

Dank je Karel. Aan de hand van de door jou geciteerde studie heb ik anomaliën composites samengesteld, voor de winters in de jaren die genoemd worden (met 1 jaar bijtelling: 2019 heeft naar verwachting invloed op winter 2020).
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Je hebt niet voldoende permissies om de bijlagen van dit bericht te bekijken.
Laatst gewijzigd door Paul op 05-03-2020 20:00, 1 keer totaal gewijzigd.

Sebastiaan
Berichten: 5740
Lid geworden op: 01-01-1978

Re: Stratosfeer winter 2019/2020

Bericht door Sebastiaan » 05-03-2020 15:37

Erg interessant. Je ziet een duidelijke positieve AO, NAO.

Karel
Berichten: 2484
Lid geworden op: 31-07-1978

Re: Stratosfeer winter 2019/2020

Bericht door Karel » 07-03-2020 20:40

Ook interessant is de gemiddelde afwijking op 500hPa op het NH in de winters na de herfst met de negatieve IOD's

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Sebastiaan
Berichten: 5740
Lid geworden op: 01-01-1978

Re: Stratosfeer winter 2019/2020

Bericht door Sebastiaan » 11-03-2020 13:04

https://www.nature.com/articles/s41586-020-2084-4
The Indian Ocean Dipole (IOD) affects climate and rainfall across the world, and most severely in nations surrounding the Indian Ocean. The frequency and intensity of positive IOD events increased during the twentieth centuryand may continue to intensify in a warming world. However, confidence in predictions of future IOD change is limited by known biases in IOD models and the lack of information on natural IOD variability before anthropogenic climate change. Here we use precisely dated and highly resolved coral records from the eastern equatorial Indian Ocean, where the signature of IOD variability is strong and unambiguous, to produce a semi-continuous reconstruction of IOD variability that covers five centuries of the last millennium. Our reconstruction demonstrates that extreme positive IOD events were rare before 1960. However, the most extreme event on record (1997) is not unprecedented, because at least one event that was approximately 27 to 42 per cent larger occurred naturally during the seventeenth century. We further show that a persistent, tight coupling existed between the variability of the IOD and the El Niño/Southern Oscillation during the last millennium. Indo-Pacific coupling was characterized by weak interannual variability before approximately 1590, which probably altered teleconnection patterns, and by anomalously strong variability during the seventeenth century, which was associated with societal upheaval in tropical Asia. A tendency towards clustering of positive IOD events is evident in our reconstruction, which—together with the identification of extreme IOD variability and persistent tropical Indo-Pacific climate coupling—may have implications for improving seasonal and decadal predictions and managing the climate risks of future IOD variability.

Karel
Berichten: 2484
Lid geworden op: 31-07-1978

Re: Stratosfeer winter 2019/2020

Bericht door Karel » 11-03-2020 13:44

Interessante publicatie Sebastiaan. In het supplement ook interessante info (Supplementary information
Coupling of Indo-Pacific climate variability over the last millennium)
Tijdens de Kleine IJstijd bij ons in de 17e eeuw wel een interessante sterke positieve IOD afwijking en in de 13e eeuw een negatieve IOD afwijking https://static-content.springer.com/esm ... M1_ESM.pdf

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Paul
Berichten: 511
Lid geworden op: 01-01-1980

Re: Stratosfeer winter 2019/2020

Bericht door Paul » 15-03-2020 18:43

Bedankt Karel en Sebastiaan voor jullie bijdrage over de IOD (DWI)

Merkwaardige waming van de stratosfeer, gegenereerd over Noord-Amerika. Niet eerder gezien.


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Hierop geattendeerd door tweet van Judah Cohen.

https://twitter.com/i/status/1237734348486565894

Binnen tien dagen zien we nog steds geen omkering van de wind (10 hPa).

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