Technical General Stratospheric Observations

CoastalStorm35

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EHF expected to reach near record levels in the next week or two.

Just our typical strong vortex or will such a big spike lead to a possible crash in the coming months?
 

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CoastalStorm35

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Jul 17, 2019
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Heat transport has well a truly shut down for business now! :eek:

EHF 10HPA.JPG


EHF 100HPA.JPG
 

snowbarbie

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What's this indicate sorry?
I think it's safest to think of the variability in heat flux as a proxy for tropospheric-stratospheric wave coupling- I am still trying to fathom the complex subject of flux theory - but as I understand it, the negative heat flux corresponds to upwards coupling...positive downwards (ie: waves of stratospheric origin coupling to the troposphere).
The mean for the SH is negative.
The forecast for heat flux (waves 1-3 )falling within the 10th percentile for heat flux distributions @10 & 100 hpa, shows how very little tropospheric wave activity is penetrating the tropopause at mid to high latitude.
 

Craig B

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Just released a week or so ago but haven't read yet https://journals.ametsoc.org/view/journals/bams/102/6/BAMS-D-20-0112.1.xml
dealing with 2019 spv weakening and impacts(eg: fire). Contributions from names that watchers of the seasonal evolution of the spv would be familiar with including Eun-Pa Lim, Amy H Butler, Zachary D Lawrence ...
Yeah had a read of that, was wanting to read more possible links to the start of the event with the record + IOD event but just brushed over really. Maybe not a main factor?
 

POW Hungry

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snowbarbie

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ens-sh-polproc-010h-Pa-20210706.png


GFS has been odd one out in these extended forecasts - on a gradual warming trend at 10 hpa for a week or more now - ZMZW doesn't seem to follow though - not sure what to make of it.

ens-sh-strat-UT-010h-Pa-20210706.png
 

snowbarbie

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Been some minor warming going on in the upper polar stratosphere

T-lat-p-90-S-70-S-zm.png


I'd think Orographic Gravity Waves with maybe a little Wave 2 action thrown in. Looks to be a perturbation generated on southern Andes. I thought wave breaking pretty much restricted to above 10hpa. Showing 5 hpa here because the colour scale gradients highlight the warming better than at 1 hpa.

a26.gif
 

POW Hungry

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Starting to see that warming leeward of the Andes, inline with perturbations showing up on the short-range GFS the forecast, this week:
1625820089955.png

Nothing out of the ordinary but something to monitor.
PV is humming, clocking in sub -90°C
1625820232287.png
 

snowbarbie

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Apparently polar vortex intensification events generally take longer than ssw counterparts to develop and mature. No impression yet of "dripping paint" descent of anomalies.

time-pres-TEMP-ANOM-ALL-SH-2021.png


time-pres-UGRD-ANOM-ALL-SH-2021.png
 
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snowbarbie

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ens-sh-polproc-010h-Pa-20210706.png


GFS has been odd one out in these extended forecasts - on a gradual warming trend at 10 hpa for a week or more now - ZMZW doesn't seem to follow though - not sure what to make of it.

ens-sh-strat-UT-010h-Pa-20210706.png
?First support in forecast eddy heat flux(begins around 25July) for previously noted forecast ramp in 10hpa temperature which GFS has been insisting on for quite awhile. See what ECMWF and NASA think in a little while.

gfs-sh-ehf-hgt-lonprs-xsect-20210713-f384.png
 
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POW Hungry

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Starting to see some heating since turning the corner at the start of this month for Southern Polar minimum for 2021.
1627384614477.png


Region of warming in the Australaisian region in the upper strat for the last week.
1627384644382.png

This looks to be a result of the ridge which looks to also be forcing some decoupling of the upper strat from lower. Seems all pretty normal as we turn the corner on winter.
1627384563251.png
 

Hermon

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Arctic is more FUBAR than The Antarctic so there's that....

The above has very little/no bearing on Strat influence, but lower trop is a fair bit bonkers ATM
1627806206439.png
It looks like a continuous conveyor of tropical heat from Indonesia to Eastern Antarctica via Darwin and the Tasman Sea...
 

snowbarbie

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Arctic is more FUBAR than The Antarctic so there's that....

The above has very little/no bearing on Strat influence, but lower trop is a fair bit bonkers ATM
1627806206439.png
A lot of ep flux convergence(below)typically confined in the troposphere since early winter this year which might account for the fragmentation of the tropospheric polar jet. Maybe things about to change if blocking highs develop in south pacific and recent anti-cyclonic formation aloft(stratosphere) persists?
gfs-sh-uzm-epfluxes-latprs-xsect-20210717-f120.png
 

Craig B

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A lot of ep flux convergence(below)typically confined in the troposphere since early winter this year which might account for the fragmentation of the tropospheric polar jet. Maybe things about to change if blocking highs develop in south pacific and recent anti-cyclonic formation aloft(stratosphere) persists?
gfs-sh-uzm-epfluxes-latprs-xsect-20210717-f120.png
Mind explaining that chart quickly above, if too hard all good.
 

snowbarbie

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Mind explaining that chart quickly above, if too hard all good.
Cant say anything really about EP flux itself....but I take it as evidence of wave breaking - nothing much above 300hpa as can be seen.... negative areas represent the change in U which I think would have to correspond to convergence - so leads to a slowing of zonal wind - the random date chosen represents what was fairly typical this early winter, the convergence of EP flux predominantly occurring below the tropopause - approximately into the zone of the tropospheric polar jet
 
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snowbarbie

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Here's where GFS (backwards) plots this heat sink airmass from:
119775_trj001.gif
Bit of a mystery.....wildcard which might be a joker but...Prince Edward islands to the south of southern Africa-another of the SH gravity wave hotspots - aligned near enough to the source position to be genuine contender.

Zonal wind streak evident on the day in the right area(at roughly the right altitude)

180-150-81-22-212-6-31-55.gif

...I conjecture the wave or waves generated moved eastwards and led to adiabatic heating by descent.
 

POW Hungry

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Starting to see that wave response on the EP-Flux plot.
Looks like we might be due another over the next few days too. A diversion of temp shift between upper/lower strat. Could be on here.
1628491054891.png
 

snowbarbie

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O3 depletion season getting impetus - watch on contribution to evolution of spv going forwards whichever way it falls.

British Antarctic Survey

Antarctic Situation at 2021 August 16​

Antarctic ozone today: The 2021 southern polar vortex is still building, so that higher ozone values, over 400 DU are seen around the continent. The stratosphere is currently fairly stable.

Ozone amounts over the continent are beginning to decline as ozone depletion commences. Lowest ozone values are currently around 220 DU and are relatively low and uniform across the continent.

The temperature of the ozone layer over Antarctica is near the winter minimum and is widely below the -78°C Polar Stratospheric Cloud (PSC) formation threshold. It is generally below the long term average.

The area with PSCs reached a maximum of around 29 million square kilometres (msqkm) in early August, above the average of 25 msqkm. It has shrunk to 26 msqkm, a little above average for the time of year.

The ozone layer temperature is highest around Antarctica and declines towards the equator and towards the centre of the polar vortex. The vortex has grown to 32 msqkm, a little above average for the time of year.

Ozone depletion is expected to increase over the coming weeks.
 
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snowbarbie

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I know that the comment was made on Amy Butler's twitter account earlier this winter(and on this forum) about the zw@60 appearing weak while SAM was strongly positive....suggesting an apparently intensifying SPV which seemed accompanied by winds more characteristic of a weakened state.

I wondered perhaps if this had a little to do with the unusually large extent of the upper stratospheric vortex at the time and particularly the appearance of dual barriers of steepened pv gradient - or dual "edges" to the spv which the chart indicates -

gfs-sh-eqltime-0800-K-20210903.png


the dual barrier(800K ~10 hpa) is visible and the gradual migration towards a single barrier at a higher latitude, is also mirrored in the location of ZW maximum.

See https://acp.copernicus.org/articles/18/8065/2018/
for more on dual pv barriers to the SPV
 

snowbarbie

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Wave propagation in August has strong correlation to ozone hole size later in spring. Once depletion is underway the associated cooling further strengthens the SPV and the jet intensifies(which in turn increases resistance to wave penetration).
This year thus far, the ozone hole looks on a trajectory like 2020. In fact the deficit responsible for the hole is currently forecast to be more extensive, in the next week, than it was at the same time last year.
cams-gl-ozone-mass-deficit-2021.png

The modelling I've seen is suggesting ZW reversal @10hpa from late Nov-early Dec predating 2020 by around a couple of weeks only
 

snowbarbie

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The modelling I've seen is suggesting ZW reversal @10hpa from late Nov-early Dec predating 2020 by around a couple of weeks only
Dr Amy Butler and Dr Daniela Domeisen suggest the median date for seasonal SPV final warming as 17 Nov
( see "The Wave Geometry of Final Stratospheric Warming Events" https://wcd.copernicus.org/articles/2/453/2021/wcd-2-453-2021-discussion.html for details)
any final warming which is more than two days before/after that date is proposed as an early / late transition.
 

snowbarbie

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Dr Amy Butler and Dr Daniela Domeisen suggest the median date for seasonal SPV final warming as 17 Nov
( see "The Wave Geometry of Final Stratospheric Warming Events" https://wcd.copernicus.org/articles/2/453/2021/wcd-2-453-2021-discussion.html for details)
any final warming which is more than two days before/after that date is proposed as an early / late transition.
The most interesting finding from the above paper though, I think is the strong reversal of possible local(to eastern Australia) surface impacts - depending on whether the FSW(final stratospheric warming) is initiated by a wave 1 / wave 2 event - associated with significantly positive/negative 500hPa geopotential height anomalies dominant in the area of the Tasman sea.
 

snowbarbie

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A little late but here's current British Antarctic Survey ozone report..
[my underlining]

Antarctic Situation at 2021 September 13​

Antarctic ozone today: Ozone amounts over the continent are declining as ozone depletion intensifies and ozone hole levels have been reached. The 2021 ozone hole has grown rapidly and covers around 21 million square kilometres (msqkm), above the average of the last decade. Lowest ozone values are currently around 160 DU. Higher ozone values are seen around the continent just outside the southern polar vortex, particularly south of New Zealand where values are over 400 DU. The polar vortex is near its maximum size, at around 33 msqkm, a little above average for the time of year. The Antarctic stratosphere currently remains fairly stable. The temperature of the ozone layer over Antarctica has passed the winter minimum but is still widely below the -78°C Polar Stratospheric Cloud (PSC) formation threshold. It is generally below the long term average. The area with PSCs reached a maximum of around 29 million square kilometres (msqkm) in early August, above the average of 25 msqkm. It has shrunk to 20 msqkm, a little above average for the time of year. The ozone layer temperature is highest around Antarctica and declines towards the equator and towards the centre of the polar vortex. Ozone depletion is expected to increase over the coming weeks
 
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PeteJ

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Hi to all the above very knowledgeable posters. For us who live in SE Qld or NE Nsw. What does it mean. A - SAM? and bushfire weather? Or the opposit.
 

POW Hungry

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Hi to all the above very knowledgeable posters. For us who live in SE Qld or NE Nsw. What does it mean. A - SAM? and bushfire weather? Or the opposit.
There's little, to no indication of a Sudden Strat Warming event this season. The polar vortex appears (at least does to me) to be undergoing natural weakening.

Thus, it looks very unlikely the Polar Vortex and its final warming will have much effect on the SAM.

IMO, we're more likely to see La Nina/QBO influence on a neutral, to +'ive SAM bias over the coming months.
 
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PeteJ

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Thanks, POW Hungry. I made a comment in the NE NSW/SE QLD Thread that the weather pattern seems to be behaving the complete opposite to the climate drivers(for our area anyway). I was thinking all we need is an SSW to really mess things up.
 
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