A candid conversation with & Sukyoung Lee on pain & progress in understanding the tropical Pacific response to climate change.
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Dr. Amy H Butler
@DrAHButler
Atmospheric Scientist at NOAA Chemical Sciences Laboratory, atmos dynamics/chemistry-climate, polar vortex expert, mother of two. Views expressed are mine.
Dr. Amy H Butler’s Tweets
1/ There has been a recent hype about the polar vortex, so I want to add some info (and an SSW poll — better late than never, see further down in thread). By “polar vortex”, I mean the stratospheric vortex at ~20-50km above the Earth’s surface over the polar regions in winter.
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Latest forecasts suggest a major #SSW is off the table for now. Just not getting the amplitude of planetary wave breaking that you typically see before a complete reversal of the #polarvortex winds. Still, will be interesting to see how things evolve in Feb!
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This week we have also published a 2-parts study based on a new multimodel intercomparison of SAI that has been long in the making by me and Ewa (mercifully not on Twitter). Here the links ->
acp.copernicus.org/articles/23/66
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I had to laugh at this example I just came across of how "polar vortex" has just become tossed around to mean cold weather .... (I promise, the #polarvortex is many miles above your concrete slabs and has no personal vendetta to wreak havoc on them)
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Replying to @ClarkEvansWx @capitalweather and @mattlanza
The term 'polar vortex' a great example* of the disconnect of how the media & public interrupt the term and how scientists interpret the term. In fact, it lead to people including @DrAHButler & @zd1awrence to contribute to a whole GRL discussion on it: doi.org/10.1029/2021GL
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"Bomb cyclone," "atmospheric river," "polar vortex": Phrases like these help raise public awareness of extreme weather events, scientists say, but could also leave us numb.
"We need significantly clearer language, not hyped words," one expert said.
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(2/2) How exactly the #vortex will evolve at 2+ weeks shows amusing levels of uncertainty. The models generally all show a deceleration, but how and where the vortex will change is completely unclear. (384h forecast shown here for entertainment purposes only).
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(1/2) At least a minor #SSW looks likely by the end of January, with most forecast models agreeing on ~30 m/s deceleration over a 6 day time period; however, whether we can get a full reversal of winds will need continued wave forcing which remains to be seen.
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If it is not literally the warmest year ever, someone will complain that global warming has stopped.
Year-to-year fluctuations are a normal part of the ongoing global warming trend. Don't be distracted by the noise.
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Appreciating 's stratosphere page today, especially with the new GEFSv12 climatologies from ! The current forecast has only a couple of members predicting #SSW, but the trend over the last few days has shown increasingly weaker zonal winds- great visualization!
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The unprecedented loss of #Antarctic sea ice continues (for this time of year)...
More graphs at zacklabe.com/antarctic-sea-. Data from .
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9 of 21 (43%) of CESM2-WACCM ensemble members from the latest update (initialised Monday) produce an SSW, mostly in early February. (CAM is the low-top model which is unlikely to fully capture stratospheric variability) acom.ucar.edu/waccm/stratosp
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Last day of #AMS2023 - we have a great two sessions on Stratosphere-troposphere coupling and links to climate! Mile High Ballroom CD. Please join us!
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Data from show that the last 8 years have been the warmest 8 years on record globally.
WMO will issue a consolidated ranking later in January based on all the major international datasets.
🔗 bit.ly/3QqUS6U
#CopernicusClimate #C3S
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This year is WQBO/La Nina, the quadrant with the overall lowest frequency of #SSWs. However, of the SSWs that occurred in that quadrant, several are the most memorable late Jan/Feb split events on record, including 1989, 2009 and 2018.
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As the PDFs (SSWs per bin of ENSO or QBO) show on the side and bottom, strong easterly QBO is associated with the biggest likelihood of SSWs, whereas the relationship with ENSO is bimodal (more SSWs in both strong El Nino and La Nina).
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Figure update: the occurrence of a single SSW (filled marker) or double SSW (filled marker with double circle) as a function of NDJ-averaged QBO50 phase and Nino 3.4 (blue for La Nina, red for El Nino). Pink dot is ND-averaged values for 2022 (this winter). A few comments:
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As an indication of how cold the #polarvortex is right now, look at the volume of polar stratospheric clouds due to NAT (nitric acid trihydrate) right now- near daily record highs! Good thing we are in polar night so this won't affect #ozone right now. ozonewatch.gsfc.nasa.gov/meteorology/te
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6. But some hope for #SSW fans among us: sometimes the vortex needs a little initial shove, and then if another (as of yet unpredicted) wave were to occur, it could happen. But as of now, this is merely a dream with little evidence from the models to support it. (/end)
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5. However, bad news for cold lovers is that often these other regimes (some of which occur when the vortex is anomalously strong, like it is now) are accompanied by regional #heat rather than cold extremes, e.g.:
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4. The wave breaking will exert a nice shove on the vortex. There is increasing evidence that #SSWs are not the only way the #polarvortex can influence weather extremes, but different locations and shapes of the vortex have unique influences. See work by or
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3. A wave breaking event is likely over the next week, though the strength of the forecasted wave is still uncertain. This will slightly slow the vortex, though note the winds are predicted to be *stronger than climatology* even after this event.
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2. By #SSW, I mean a reversal of the westerly winds at 10 hPa and 60N, which are currently extremely strong (90th percentile).
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New year, same overall story with regard to the strength of the stratospheric polar vortex: the latest run of the subseasonal ECMWF prediction system has a stronger-than-average vortex all the way into February -- with no ensemble members showing an SSW in the next 4 weeks.
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There is a lot of #twitter debate about the near to extended range #polarvortex forecasts, so let’s review what is going on (a 🧵):
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The lack of #Antarctic sea ice going into the new year is clearly an outlier compared to any other year in our satellite record.
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And you can find some great new plots of the GEFS 35-day U10-60 forecast from - arctic.som.ou.edu/tburg/products
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Europe is experiencing its worst heatwave ever recorded.
The combined intensity and scale of this winter heatwave is unlike anything in European history.
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Note that the latest ECMWF forecast shows this wave pulse merely reducing the strong #polarvortex to average wind speeds. Additional unpredicted wave breaking would need to happen to further slow the winds. In this model *no* ensemble member shows an #SSW in the next 3 weeks.
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The Northern Hemisphere #polarvortex currently has near record low temperatures, but the #GFS at least is showing signs of a large wave-1 event in the coming weeks, accompanied by up to a 30 m/s slowdown and 10-20K warmup. No #SSW predicted yet but something to keep an eye on.
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The Northern Hemisphere #polarvortex currently has near record low temperatures, but the #GFS at least is showing signs of a large wave-1 event in the coming weeks, accompanied by up to a 30 m/s slowdown and 10-20K warmup. No #SSW predicted yet but something to keep an eye on.
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What would be the mechanism for making the cold extremes "colder"? The sourced arctic air should be warmer. After all, the wintertime deep arctic is by far the place experiencing the strongest warming signal.
[4/n]
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Interested in Stratosphere-Troposphere Coupling? Working on Stratospheric Dynamics? Expert on Sudden Stratospheric Warmings? Please consider submitting your work to our #EGU23 session "Stratospheric Dynamics"
meetingorganizer.copernicus.org/EGU23/session/
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Thanks to the ENSO blog for having me and guest author this post on the globe’s information superhighways- Rossby waves. 🛣
It’s Teleconnections 101!
You’ll find some links in there too 🦋
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Wonder how something a thousand miles away can affect the weather where you live? At the ENSO Blog, guest bloggers @breannazavadoff and @mbarcodia explain how Rossby waves create a globe-spanning superhighway that connects climate patterns.
climate.gov/news-features/
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😬over-simplified descriptions of the polar vortex obscure the truth and cause confusion, IMO.
And the article starts out with the science sin of "the polar vortex is descending on the US, bringing cold air"
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What’s the big deal about mixing terminology? What the polar vortex will do in the future & what the polar jet stream will do may be entirely different. And despite what either one will do, eventually global warming will win out over both if co2 emissions continue.
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Conveying science is hard, but there’s been enough pushback that these sorts of errors (mishmashing “polar vortex” and what should really be called a “polar front”) should no longer be an issue, yet winter after winter they pop up.
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over-simplified descriptions of the polar vortex obscure the truth and cause confusion, IMO.
And the article starts out with the science sin of "the polar vortex is descending on the US, bringing cold air" @nytclimate nytimes.com/2022/12/22/cli2
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Just retweeting this from Feb 2021.
We expect cold-air outbreaks (CAO) to get *less severe* with climate change, as the source region (the Arctic) warms more than the mid-latitude.
There is not sufficient evidence that climate change is making CAOs more severe or frequent.
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Cold outbreaks will continue to happen even in a warming climate. But these types of atmospheric circulation patterns are expected to bring relatively less cold conditions in the future, as per the crude analysis below.
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