Anti-cyclones over SE Australia versus snow depth

Discussion in 'Alpine & Southern' started by teleroo, Jun 20, 2019.

  1. teleroo

    teleroo One of Us Ski Pass: Silver

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    This recent study by Acacia Pepler & co. describes a tale of more high pressure systems occurring over south eastern Aus in recent decades. From a snow perspective, these stupid highs keep the snow bearing weather systems well to the south. Explains some of the long term declines in snow depths, sadly.

    From a climate change perspective, I'd always accepted the physics of CO2 being an insulative gas, and in some sort of conceptual column, could accept a higher CO2 concentration would lead to greater heat retention. But as I'd always considered "the weather" to be a more function of winds, pressure patterns and airmass movement etc, I'd always had a mental gap between the increased insulative properties of a gas within an abstract column and real on the ground weather. However, this study would seem to fill that gap. Greater atmospheric heat retention due to increased CO2 concentration would seem to be enhancing the Hadley Cell, with a stronger downdraft along the sub-tropical ridge (ie stronger anti-cyclones over Aus), manifesting in less of what we all like here, snow.

    https://link.springer.com/epdf/10.1007/s00382-019-04819-9?author_access_token=45rF8WRELZ-MojG2XaT-iPe4RwlQNchNByi7wbcMAY4iiywiUo50pnNJDU-g6P2Mi2xXGmZNjsl-ocavKI5dP1iy2uhSf6CsYFWv8Nm16tKSh4Wqk9MuY_xgSV62BeKS6vinYLKar7t-0K5hZQKKWQ==

    Read this article in conjunction with another great graphic I found recently on the internet. Unfortunately a bit depressing, I feel bad for my kids who've just caught the snow bug.

     
    #1 teleroo, Jun 20, 2019
    Last edited: Jun 22, 2019
  2. Red_switch

    Red_switch Old n' Crusty Ski Pass: 30 Day

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    Nice paper, and aren't joyplots great? Care to guess what this is (it's not unrelated)?


    It's based on the data from a paper I've just had accepted, which offers you a potential solution... we can't detect a trend in snow cover, or snow line elevation in NZ from ("easily observable") snow metrics. Inter-annual (and spatial) variability is ridiculous though, and we can relate that to anomalous winter airflow.
     
  3. teleroo

    teleroo One of Us Ski Pass: Silver

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    My guess is some sort of terrain model with a valley draining to the bottom of the image? Am thinking view north-westwards over Lake Jindabyne, but if so the Crackenback fault scarp doesn't appear as prominent as I would have expected...
     
  4. CarveMan

    CarveMan Pool Room Ski Pass: Gold

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    Only slightly related to this excellent post, but I am wearing this T-Shirt today:

    [​IMG]
     
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  5. teleroo

    teleroo One of Us Ski Pass: Silver

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    Southern Lakes South Island?
     
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  6. Red_switch

    Red_switch Old n' Crusty Ski Pass: 30 Day

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    Yeah, you're on the right track geographically. But it's not topography.
     
  7. Red_switch

    Red_switch Old n' Crusty Ski Pass: 30 Day

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    I've got a script I can sell them ;)
     
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  8. teleroo

    teleroo One of Us Ski Pass: Silver

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    Some sort of snow depth variable as Z, position as X,Y? Seems to line up with general topography though, which is a reasonable proxy for snow depth, aspect aside. Lake Wakatipu seems to be manifest in one form or another as a bit of distinctive pattern.
     
  9. Red_switch

    Red_switch Old n' Crusty Ski Pass: 30 Day

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    Ding ding ding.

    It's mean snow cover duration (i.e., the number of days a year snow is on the ground) from a satellite observation record. Yep, Wakatipu, Wanaka and Hawea are all there, and Ohau too. It's a bit more obvious in an orthographic view than the oblique perspective there.

    This is the whole thing, it's all geographically correct in terms of NZTM projection (tossing up going down the t shirt path, have been getting a lot of requests from mates haha):
     
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  10. teleroo

    teleroo One of Us Ski Pass: Silver

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    Anyway, back on topic. Nice to hear NZ snow is holding up (if wonky year to year). The problem we seem to be having here in Aus with the change in pressure patterns, is two fold. Firstthe strong anti-cyclones are more prone to keeping cold fronts well to the south. But also, with more persistent highs over the Tasman, their western halves seem particularly effectively at dragging heat from NW Western Australia (Kimberly, Pilbara, Broome etc) and central Aus over south eastern Australia. We just had this in early June 2019, after 71 cm of snow fall in late-May early June, we lost 40 cm in about five days of not-below-zero temperatures. Summer 2018-2019, temp records were smashed out of the park as heat from the heat engine of NW Australia was consistently stream the south east across the continent by a high east of Australia. We were lucky that there weren't big winds associated with it from a bush fire perspective. But it was a very very unpleasant run of hot days. Seems the new norm. Makes the move to NZ seem a little tempting....



    This was the recent weather in June that smashed the best start in 20 years...

     
  11. POW_hungry

    POW_hungry Part of the Furniture Moderator Ski Pass: Gold

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    May, June are susceptible to blocking high patterns.
    Whilst we haven’t seen much of a blocking pattern in our region this month, the good snowfalls at the start of June were an anomaly, not the High pressure ridging.
     
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