Advertisement
Boards Golf Society are looking for new members for 2022...read about the society and their planned outings here!
How to add spoiler tags, edit posts, add images etc. How to - a user's guide to the new version of Boards

The Sudden Stratospheric Warming 2011/2012

«1345

Comments



  • Despite having followed this before both here and netweather, i can't remember a single thing about it! Time to start reading up again I think!




  • I've done a bit of reading on it over the past week since the netweather thread started up, there's a good explanation of it here

    http://forum.netweather.tv/topic/71340-stratosphere-temperature-watch-20112012/




  • That went completely over my head.

    So a sudden warming is good or bad sign for the winter.

    For reference

    good = cold and snow

    Bad = mild and wet

    :D




  • Lucreto wrote: »
    That went completely over my head.

    So a sudden warming is good or bad sign for the winter.

    For reference

    good = cold and snow

    Bad = mild and wet

    :D

    Stratospheric warmings: Meteorologists identify cause of cold and warm periods during winter
    stratosphere_diagram.jpg

    ScienceDaily (2011) — Meteorologists at Freie Universität have found a correlation between warming in the stratosphere and cold or warm winter periods. They observed that there is an increased number of stratospheric warmings, when the heat flow from the North Atlantic into the atmosphere is increased. Trends for winter temperatures can be derived from these new findings.

    “This could mean that in Europe there will increasingly be periods lasting several decades with predominantly colder winters alternating with periods of warmer winters,” says Semjon Schimanke, who led the research, reported in the journal Geophysical Research Letters. The meteorologists expect that in the long term their research will help weather forecasters make more accurate predictions.

    The phenomenon of stratospheric warming was first discovered in 1952 by Professor Richard Scherhag at the Institute of Meteorology, Freie Universität Berlin. It appeared in the scientific literature as the “Berlin phenomenon.” In the meantime, these events are referred to as “sudden stratospheric warmings,” and 30 have been registered so far.

    On average, sudden stratospheric warmings occur in every second winter, and they are very unevenly distributed over the observation period. Only a single stratospheric warming occurred between the winters of 1988/1989 and 1997/1998, while nine have been registered since the beginning of this millennium. So far there has been no explanation. With their new research, the meteorologists at Freie Universität have shown that the intermittent sudden stratospheric warmings are a consequence of the interaction between the North Atlantic, the troposphere, and the stratosphere. They found that an increased number of sudden stratospheric warmings occur when the heat flux from the North Atlantic into the atmosphere is increased.

    During the winter months in the lower polar stratosphere, which lies approximately 20 kilometers above the Earth’s surface, temperatures on average are below minus 70 degrees Celsius. The cold temperatures are combined with strong westerly winds that form the southern boundary of the so-called stratospheric polar vortex. This dominant structure is disrupted in some winters or even reversed. Under these conditions the temperatures in the lower stratosphere rise within a few days by more than 50 degrees, and the polar region is warmer than southerly latitudes. This implies a reversal in the west-east winds and the collapse of the polar vortex. Using models and observations, it was possible to show that such sudden stratospheric warmings are initially excited from the troposphere, but then also have a strong influence on tropospheric circulation.

    After a sudden stratospheric warming, among other things the differences in pressure between the Icelandic Low and the Azores High are reduced. This pressure difference determines the prevailing wind direction for Central Europe and thus determines whether the European winter turns cold or warm. Thus, for example, the 2009/2010 winter was characterized by a highly disturbed polar vortex, and in many parts of the Northern Hemisphere there was a severe and snowy winter.




  • Lucreto wrote: »
    That went completely over my head.

    So a sudden warming is good or bad sign for the winter.

    For reference

    good negative NAO = cold and snow

    Badpositive NAO = mild and wet

    :D
    thats my understanding of it,very interesting(:confused:) what ever the winter brings


  • Advertisement


  • I've circled on below chart the Polar Vortex at the end of Jan 09 during the Major Strat Warming which tore the PV to shreds and reversed the normally strong westerly winds to easterly.This gave us the cold weather soon after.

    179979.JPG


    The Arctic Oscillation had to drop.

    179984.JPG



    And so the end result the negative (COOL) phase and great chance of being cold and snowy.

    179985.JPG




  • Nothing too exciting to report as of yet.
    I'll also just pop on here the Zonal winds graphs.



    fluxes.gif




  • Started reading the given links.
    I've a splitting headache.
    I have to lie down.




  • redsunset wrote: »

    179985.JPG

    On the above image, The high pressure over the arctic, Is this the high pressure we look to build over greenland? Or is it something completely different?

    I'm going to read the links later when i have the chance.




  • baraca wrote: »
    On the above image, The high pressure over the arctic, Is this the high pressure we look to build over greenland? Or is it something completely different?

    I'm going to read the links later when i have the chance.

    Here ya go,
    Firstly show positive AO conditions so low heights over high latitudes and a strong Polar Vortex,as in westerlies dominant.

    AO_Positive_2.gif


    Next up the opposite and the crème de la crème for cold lovers,
    Negative AO and weak Polar Vortex.

    AO_Negative_2.gif


    This is why we like to monitor the Stratosphere as warmings can disrupt the normal strong westerly Polar Vortex and potentially reversing them.
    This all can contribute to Negative AO conditions.

    Hope this makes more sense to people.

    Images are from this site.Have a look as it also explains the NAO.Tis very well put together.

    http://www.nc-climate.ncsu.edu/climate/patterns/NAO.html


  • Advertisement


  • A simple way to look at all this strat warming is a bucket of water.

    You have a bucket of water. The water represents the atmosphere, and the centre of the bottom of the bucket, the North Pole. Set the water stirring in an anticlockwise direction. A depression will form in the centre of the surface of the water, while the water rises slightly up the side of the bucket. This simulates the polar vortex. The low height of the water in the middle of the bucket represents the low heights in the cold winter airmass over the Pole. Heights rise around the sides, like heights rise as we head to lower latitudes. This is what drives the strong westerly winds.

    Now imagine if you stick your hand into the water, near the edge of the bucket. Watch the flow of the water. As it reaches your hand, it will deflect inwards towards the centre, then swing around to flow in the opposite direction behind your hand. This is what happens in stratospheric warming. A disturbance from low down in the troposphere interrupts the westerly flow in the stratosphere, with temperatures and hence heights rising as a consequence. This causes the flow to become broken down, and even reversing to from an easterly direction. This can cause a so-called split vortex, and after a week or so, the easterly winds can migrate downwards into the troposphere. This is usually where our coldest airmasses come from, so it is nice to watch for the these strat warming events, which normally come around every one to two years. If we see a decent one forming, there is a chance that we could see some blocking forming aa week or two down the road.




  • Movin' on up!......finally!

    184517.gif




  • Joe Bastardi says,

    Stratwarm event starting in Siberia in about 10 days similar to set up for 1984-1985 winter
    Now i was curious to i checked up for us boardsies at what the 500mb Geopotential Heights were for the month of Jan of 1985,And simply smiled when i saw

    THIS

    184757.JPG




  • redsunset wrote: »
    Joe Bastardi says,

    Stratwarm event starting in Siberia in about 10 days similar to set up for 1984-1985 winter
    Now i was curious to i checked up for us boardsies at what the 500mb Geopotential Heights were for the month of Jan of 1985,And simply smiled when i saw

    THIS

    Made my day! :)




  • BEASTERLY wrote: »
    Made my day! :)

    I take it we might get a little snow from this:D:D any links to Irish weather in 1984-1985. All i can find is US polar vortex




  • Hmm I lived in on the East Coast during these winters. Great snow. Loads of time off school.

    But I now Live in the West (East of Galway) so what was the snow like during 84-85?




  • I must admit I'm still slightly confused but thanks Su for explaining in basic terms for us physics challenged people :D

    Red was the last chart you posted from 84/85 if so how is the same chart looking today? Also I'm pretty colour blind (a major bummer when trying to chart read) so if you or anyone else for that matter could stick in a brief description/comparison of the 84/85 chart and the one now it would be much appreciated :)




  • All about Jan/Feb 1985
    http://www.ukweatherworld.co.uk/forum/index.php?/topic/49683-


    As for the colour blindness,sorry mate.So i direct you back to the previous post 11 with labels on Northern Hem chart about height rises and a weakened Polar Vortex.Click on link provided,gives great info.




  • redsunset wrote: »
    All about Jan/Feb 1985
    http://www.ukweatherworld.co.uk/forum/index.php?/topic/49683-


    As for the colour blindness,sorry mate.So i direct you back to the previous post 11 with labels on Northern Hem chart about height rises and a weakened Polar Vortex.Click on link provided,gives great info.

    just what i wanted, ta very much


  • Advertisement


  • From a poster over on netweather:

    The GFS is forecasting a far stronger warming that is showing signs of propagating to lower levels. I think that this is being reinforced by another bout of strong wave activity breaking into the stratosphere. The ECM has a really strong warmining at 1hPa that i9s forecast to diminish rapidly at T+ 192 after breaking through the surf zone. I think that this could because the warming is propagating further down the vortex - but that this has yet to show up significantly on the ECM charts yet.

    http://wekuw.met.fu-...ast=all&lng=eng

    However at T+240 on the GFS at 30 hPa we see this:

    index.php?app=core&module=attach&section=attach&attach_rel_module=post&attach_id=124962

    This is very encouraging indeed and will start to have an effect on the vortex come the new year even without an SSW.

    Very, very promising indeed.




  • Yea agree with what Nacho posted, just noticed this forcasted warming a few minutes ago-

    temps.gif

    This shows a warming at the 30hpa level at 90N, Data from the ECM by the way! :D

    Great news! :D;)





    Dan :cool:




  • Taken from NW :


    For the first time this winter we are about to see the stratosphere taking a big hit with remote wave breaking over the top of the stratosphere. It would be interesting to see the latest MT readings. Are we seeing a resurgent MT event deflecting these wave?

    Here is the momentum flux forecast for both waves - very strong activity seen here propagating into the mid stratosphere.

    185332.png

    So how does this effect the polar vortex? Well the wave introduces warmer air into the vortex. The edge of the vortex is known as the surf zone and to cause maximum disruption we would like to see the warmer penetrate this strong barrier. And when we look at the 1 hPa chart right at the top of the stratosphere we see exactly that occuring.

    185333.png

    This is important because getting the warm air right inside the vortex will squeeze the colder air out, mix and cause a reduction of the vortex strength. However this is right at the top of the stratsophere and to benefit tropospherically from this we need to see the same ocuring at lower levels. Today at the 30 hPa we are seeing signs that this is occurring.

    185334.png

    Now this presently is not enough to cause a SSW - we would need to see far greater warming for this ( but can't rule out that happening from this wave either). But it is enough to cause a displacement of the vortex.
    And if this forecast comes to fruition then we will have far more to look forward to coming into the new year as further waves feed back into the stratosphere. With a reduction of the vortex for the first time this winter the door would be opening for northern blocking to occur.




  • From a poster over on netweather:

    The GFS is forecasting a far stronger warming that is showing signs of propagating to lower levels. I think that this is being reinforced by another bout of strong wave activity breaking into the stratosphere. The ECM has a really strong warmining at 1hPa that i9s forecast to diminish rapidly at T+ 192 after breaking through the surf zone. I think that this could because the warming is propagating further down the vortex - but that this has yet to show up significantly on the ECM charts yet.

    http://wekuw.met.fu-...ast=all&lng=eng

    However at T+240 on the GFS at 30 hPa we see this:

    index.php?app=core&module=attach&section=attach&attach_rel_module=post&attach_id=124962

    This is very encouraging indeed and will start to have an effect on the vortex come the new year even without an SSW.

    Very, very promising indeed.

    And he seems to be very happy with again today also .

    185337.png

    Good GFS as well today.

    I love the shape of the warming seen at the 10 hPa level.Here is the 30 hpa level for T+240

    185338.png

    And distortion of the vortex starting - we will need a greater warming than this to give a SSW .




  • As long as were heading in the right direction I'm happy.




  • I've picked out 2 examples looking at the table.
    185540.JPG
    Here's the Dec 84 Pacific blocking prior to the split PV in Jan 85

    archivesnh-1984-12-19-0-0.png

    Pacific/Atlantic blocking prior to 1963 split PV

    archivesnh-1963-1-18-0-0.png




  • whats east of us now is pretty warm
    7c in romania and poland.
    Only around zero in moscow.

    No building blocks visible to even hint at december 10 cold.

    What red sunset has pointed out are 2 random years.Thats only saying somethings possible but then the same could be said for roaring southwesterlies if you examine winters they've happened.
    It means nothing unfortunately forecast wise without building blocks.




  • Just to clarify i wasn't forecasting anything,just simply showing for my own and others interest what the Northern Hemisphere blocking looked like prior to some major cold outbreaks as highlighted in the PDF as to the precursor to Polar Vortex splitting events.Is that Ok, Black Briar. Not giving anyone false hopes here.

    Yes conditions to the immediate east are fairly sh1te at the moment,past that and there's the tap so everywhere to our east will have to cool down immensely first to get the holy grail.

    201148.png


  • Advertisement


  • if there is a change in the nh pattern that leads to blocking, i wouldn't get caught up in how warm it is now further east in comparison to normal, it would obviously take that bit longer to cool down, but cool down it would. Let's worry about getting the right parameters in place first.

    also bear in mind:. From January 22nd to March 17th 1947, snow fell every day, somewhere in the UK! So we've plenty of time for it to get colder.


Advertisement