Another good round up by Gavin as we lead into winter (video below). One thing I would question is the discussion regarding the anomalous QBO.
The quasi-biennial oscillation (QBO) is a tropical lower stratospheric, downward propagating zonal wind variation, with an average period of ~28 months. The QBO has been constantly documented since 1953. Here we describe the evolution of the QBO during the Northern Hemisphere winter of 2015–2016 using radiosonde observations and meteorological reanalyses. Normally, the QBO would show a steady downward propagation of the westerly phase. In 2015–2016, there was an anomalous upward displacement of this westerly phase from ~30 hPa to 15 hPa. These westerlies impinge on or “cutoff” the normal downward propagation of the easterly phase. In addition, easterly winds develop at 40 hPa. Comparisons to tropical wind statistics for the 1953 to present record demonstrate that this 2015–2016 QBO disruption is unprecedented.
The anomalous change in the QBO in 2015–2016, Newman 2016
Gavin does look back at some reanalysis at the turn of the last century but this misses out periods such as Solar Cycle 12 and 5, the latter during the Dalton Minimum. Do we know how the QBO behaved then?
Are these relevant? Who knows, but I would argue they are more relevant than a mention climate change or even to a degree the recent ENSO fluctuation – the latter begs the question of what caused it and there are other naturally forced candidates that must be explored/ruled out long before we look to human causes;
long term Lunar atmospheric tides could be acting as a trigger to favor either El Niño (positive PDO) or La Niña (Negative PDO) conditions
ARE GLOBAL MEAN TEMPERATURES SIGNIFICANTLY AFFECTED BY LONG-TERM LUNAR ATMOSPHERIC TIDES? Wilson 2013
We also have to factor in that the QBO was only discovered in the 1950’s. Drawing premature conclusions based on limited data is not wise, nor is mentioning climate change (which sadly is used to explain everything and thereby explains nothing).
For example in The quasi-biennial oscillation of 2015–2016: Hiccup or death spiral?, author Dunkerton 2016 writes [my bold]:
While the basic fluid-dynamical mechanism of the QBO is firmly established through analog studies in the laboratory, the details, especially of wave forcings, are not well understood.
We have a solar disc exhibiting behaviour not seen in over a century or two. Mike Lockwood – with the caveat that human induced warming would overpower any effect – states the sun has been exhibiting behaviours not seen in four centuries;
The Maunder Minimum coincided with the worst European winters of the little ice age, a period lasting centuries when several regions around the globe experienced unusual cooling. Tree ring studies suggest it cooled the northern hemisphere by up to 0.4 °C.
But Lockwood says we should not expect a new grand minimum to bring on a new little ice age. Human-induced global warming, he says, is already a more important force in global temperatures than even major solar cycles. Temperatures have risen by 0.85 °C since 1880, with more expected, according to the most recent assessment of the Intergovernmental Panel on Climate Change.
There may still be noticeable consequences. For instance, long term cold winters in the UK are common when solar activity is low. And less solar activity can slow the jet stream, triggering a suite of interlinked extreme weather events like the Russian heatwave of 2010, and the devastating floods in Pakistan that same year.
Solar wind, affected by Coronal holes, may also affect the QBO:
The solar wind QBO may influence the stratospheric QBO, the global electric circuit, and cloud cover by modulation of ionospheric electric fields, cosmic ray flux, and particle precipitation
QBO in solar wind speed and its relation to ENSO, Hocke 2009
A significant correlation between the solar wind speed (SWS) and sea surface temperature (SST) in the region of the North Atlantic Ocean has been found for the Northern Hemisphere winter from 1963 to 2010, based on 3-month seasonal averages. The correlation is dependent on Bz (the interplanetary magnetic field component parallel to the Earth’s magnetic dipole) as well as the SWS, and somewhat stronger in the stratospheric quasi-biennial oscillation (QBO) west phase than in the east phase. The correlations with the SWS are stronger than those with the F10.7 parameter representing solar UV inputs to the stratosphere. SST responds to changes in tropospheric dynamics via wind stress, and to changes in cloud cover affecting the radiative balance. Suggested mechanisms for the solar influence on SST include changes in atmospheric ionization and cloud microphysics affecting cloud cover, storm invigoration, and tropospheric dynamics. Such changes modify upward wave propagation to the stratosphere, affecting the dynamics of the polar vortex. Also, direct solar inputs, including energetic particles and solar UV, produce stratospheric dynamical changes. Downward propagation of stratospheric dynamical changes eventually further perturbs tropospheric dynamics and SST.
Correlations of global sea surface temperatures with the solar wind speed, Zhou & Tinsey 2016
So we have natural agents (albeit not politically acceptable) that are able to perturb the atmosphere, and it is likely such perturbations could cause the anomalous QBO. Returning to Dunkerton 2016;
For the QBO to fail, even if only a hiccup, the stratospheric dynamical system either must lie near some kind of critical tipping point, or the tropospheric forcings that drive the QBO (or at least some of them) must deviate outside the range established by the seasonal cycle and typical ENSO events. In this regard, the latest ENSO is unusual owing not only to its NH summer onset but the way in which the tropical Pacific atmosphere was affected. Tropical cyclone (TC) formation exploded in the central Pacific, normally a quiet region for genesis, while East and West Pacific sectors saw TC activity suppressed. Particularly remarkable is a record-setting drought in TC formation in the tropical western North Pacific (199 days) [Klotzbach, 2016] where such activity is common year round, unlike all other sectors. If one is looking to explain the QBO anomaly in terms of wave sources and transmission in the context of the standard model, the warm ENSO event of 2015–2016 is a very large smoking gun: in several respects, placing the tropical tropospheric circulation outside the range of normal seasonal and interannual variability. It is thought that ENSO warm events enhance the B-D circulation [Calvo et al., 2010] but to be consistent with slightly faster descent of westerlies there must exist another process, perhaps enhanced Kelvin wave activity, to overcome the anomalous upwelling. Although Singapore lies west of the primary ENSO region, a robust signature of Kelvin waves is evident here throughout the 2015–2016 QBO anomaly [Newman et al., 2016, Figure 2a].
So are there other possibilities? Yes. What caused the large ENSO oscillation? Carbon dioxide has been steadily increasing and it is hard to see how it could suddenly start affecting us after the hiatus, especially when the Global Circulation Models have performed so poorly but magically because of a long predicted strong ENSO all is fine and dandy again with predictions of thermageddon climate disruption?
By contrast, solar behaviour has been anything but steady. Most certainly it is going to be some time before we have answers or indeed discover if this is a unique event or not. As with many ‘unprecedented’ incidences regarding weather it depends on the timescales used. However, without a doubt the current behaviour has thrown a rather large spanner into many long range forecasts.