Happy New Year 2024 (and sorry for the forum being offline some hours) /DM
Quote@simondonner: Like any good horror movie, the Blob may have a sequel #climate #oceanshttps://twitter.com/simondonner/status/776847157030559744
@simondonner: Like any good horror movie, the Blob may have a sequel #climate #oceanshttps://twitter.com/simondonner/status/776847157030559744
Michelle L. Heureux at Climate.gov has a new blog text about the shrinking odds for a La Niña: https://www.climate.gov/news-features/blogs/enso/incredible-growth-2015-16-el-ni%C3%B1o-followed-incredible-shrinking-la-ni%C3%B1aSleepy: yes, a huge jump in the Niño indexes in just a few days.
SH & ASLR, I think we might see neutral ENSO conditions throughout 2017, the outlier right now that do predict La Nina conditions for winter is JMA. But SST's in the Nino4 region seems to have bottomed out now. And while there's another subsurface cold pool in the western pacific, it is far from the anomalies we saw earlier this year. Total heat content by TAO/Triton indicates dissipating colder anomalies.And for the present increase in the SOI, autumn is the usual time for weather patterns to change. More notable is that the SOI has been consistently near zero for June, July and August. Also notable is the rapid phase change in the QBO. Whatever that sudden dive to zero will lead to, it will affect seasonal forecasting since it affects the forecasted NAO. And the QBO used to be the boring old faithful of oscillations. It's not anymore.Low sea ice favors a strengthened Siberian high and/or a weaker winter polar vortex. A weaker polar vortex will support SSW's, and so on.2017 will likely not beat 2016, but I see no real stall ahead, we just took another step up in global temperatures. My guess is that 2017 will provide a new record low extent in the Arctic and Antartica will follow within the next four years.In short, I wish to see a stall ahead but I can't see it right now.
AbstractAlthough there in general are no significant long-term correlations between the QBO and the ENSO in observations we find that the QBO and the ENSO were aligned in the 3 to 4 years after the three warm ENSO events in 1982, 1997, and 2015. We investigate this indicated relationship with a version of the EC-Earth climate model which includes non-orographic gravity waves. We analyze the modelled QBO in ensembles forced with climatological SSTs and observed SSTs. In the ensemble with observed SSTs we find a strong and significant alignment of the ensemble members in the equatorial stratospheric winds in the 2 to 4 years after the strong ENSO event in 1997. This alignment also includes the observed QBO. No such alignment is found in the ensemble with climatological SSTs. These results indicate that strong warm ENSO events can lock the phase of the QBO.
Key points:• In the years after the warm ENSO events, 1982, 1997, and 2015, the QBOand the ENSO were aligned.• In climate model ensemble with observed SSTs the QBOs align after astrong warm ENSO event.• The climate model with observed SSTs reproduces observed relation betweenQBO phase propagation and ENSO.
The El Nino-Southern Oscillation (ENSO) and the Quasi-Biennial Oscillation (QBO)are the two most conspicuous modes of variability in the atmosphere. The QBO is aquasi-periodic oscillation in the tropical stratosphere with a mean period of around 28months [for a review, see Baldwin et al., 2001]. It is an internal atmospheric mode forcedby waves propagating from the troposphere. The QBO influences the northern hemisphereextra-tropical stratosphere [Holton and Tan, 1980; Gray et al., 2004] and also impacts thetroposphere. For example, both the strength of the tropical Hadley circulation [Gray et al.,1992] and the Madden–Julian oscillation [Yoo and Son, 2016] have been reported to bemodulated by the QBO. The ENSO [for a recent review, see Wang et al., 2012] is a coupledatmosphere-ocean mode in the tropical Pacific featuring a broad temporal spectrum witha preferred timescale of 3-5 years (Fig. 1). The ENSO has a large effect on weather in thetropical and extra-tropical troposphere and is also a source of predictability on extendedrange time-scales in the extra-tropics. There are also studies that show an effect of theENSO on the northern hemisphere stratospheric vortex [van Loon and Labitzke, 1987;Mitchell et al., 2011]. See the recent paper by Hansen et al. [2015] for further literatureand for a model study of non-linear impacts connected to both the QBO and the ENSO[Butler et al., 2014].In spite of the various and extensive impacts of the two modes of variability, and a documentedrelationship between the ENSO and the upwelling in the tropical lower stratosphere[Simpson et al., 2011], there is no observed direct, linear relationship. For example,the correlation between the MEI (Multivariate ENSO Index) and the zonal mean zonal winds in the equatorial stratosphere is not significantly different from zero (Fig. S1).However, a relationship between the phase propagation of the QBO and the phase of theENSO has previously been found in observations [Taguchi, 2010; Yuan et al., 2014]. Thiswas further investigated by Schirber [2015] who, in a series of idealized model simulations,found that the speed of the downward propagation of the westerly QBO depends on theENSO conditions.The present study is inspired by the observation (Fig. 2) that the three strongwarm ENSO events beginning in 1982 [Philander, 1983], 1997 [Wolter and Timlin, 1998;McPhaden, 1999], and 2015 are accompanied by the same phase of the QBO (positiveindex at 50 and 30 hPa). These three warm ENSO events are the strongest in the periodsince 1950 where both stratospheric data and the MEI index are available. Together withthe vanishing long-term correlations this suggests a non-linear relationship between theQBO and the ENSO with only strong ENSO events having an influence.Studies of the QBO/ENSO relationship are challenged by the relatively short periodwith observations and the difficulties in obtaining realistic QBOs in climate models [Gior-getta et al., 2002]. Version 3 of the climate model EC-Earth (The EC-Earth Consortium’sclimate model) includes non-orographic gravity waves and has a very good representationof the stratosphere including a spontaneous QBO [Orr et al., 2010]. We will use AMIPtype(Atmospheric Model Intercomparison Project) ensemble experiments to show thatthe relationship between the phase-speed of the QBO and the phase of the ENSO is wellrepresented in the model. We will also demonstrate that the warm ENSO event in 1997leads to an alignment of the modelled QBOs in the different ensemble members. This latter result and the observed alignment after the warmest ENSO events indicate thatstrong warm ENSO events can lock the phase of the QBO.
