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Author Topic: Atmospheric connections, structure, and long range weather forecasting  (Read 39195 times)

sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #400 on: October 20, 2020, 08:59:17 PM »
Find me another single month that is split at 500mb in the NH as I have shown repeatedly and I would reconsider this stat as a measure of anything.  feel free to adjust the scale, it may be not what I am imagining.

pointing at a massive average of the geopotential heights is not yet useful, and when it becomes apparent that annual or even seasonal averages are split at 500mb, I'm not confident we will retain the capacity to observe it.

The Earth is still round.. Is that the test?

Is splitting at 500mb a useful test?  It's a valid question.
« Last Edit: October 20, 2020, 09:22:01 PM by sark »
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sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #401 on: October 20, 2020, 09:28:50 PM »
It seems that what would clear things up is a simple vorticity heat map of the hemisphere.  This might show that the split in heights is accompanied by a split in vorticity, which is really the issue.  Anyone got that?
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El Cid

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #402 on: October 20, 2020, 11:10:20 PM »
you are right
2020 October is highly unusual

sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #403 on: October 21, 2020, 12:37:41 AM »
Wow, it really is.  Hopefully a lot of this fills in as we had peak events around the 4th and 17th of the month.
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sark

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #404 on: October 22, 2020, 07:36:03 AM »
Building in positive AAM could change the polar blocking situation in coming months, but unlike last year, our La Nina episode favors more negative AAM.

Looks like we're coming into a seasonal acceleration,  but in La Nina perhaps not as much as last year.

https://www.aer.com/science-research/earth/earth-mass-and-rotation/special-bureau-atmosphere/
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Glen Koehler

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Re: Atmospheric connections, structure, and long range weather forecasting
« Reply #405 on: October 29, 2020, 11:34:16 PM »
Warmer climate and Arctic sea ice in a veritable suicide pact https://yaleclimateconnections.org/2020/10/warmer-climate-and-arctic-sea-ice-in-a-veritable-suicide-pact/

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      Excerpt:  “Ever since the record-smashing summer of 2012, Arctic scientists have watched melt seasons unfold with bated breath: Will this year break the record again? Will this year bring the long-anticipated sea-ice-free summer?” said climate scientist Jennifer Francis of the Woodwell Climate Research Center. “And almost every August, the rate of ice loss came to a screeching halt, averting a new record minimum. But why?”

"What froze the death spiral?
      Francis and her co-author Bingyi Wu of Fudan University in Shanghai have a theory that the rapid warming in the Arctic prompted a change in the polar jet stream, the narrow band of strong wind circling the region; they theorize that this change helped preserve some sea ice. Their new study in Environmental Research Letters notes that the winter and spring sea ice extent reached record low levels nearly every year since 2012 … but then the trajectory took a sharp turn late into the summer season, with the loss curbing early and therefore avoiding setting a new record low annual minimum in September.

      Francis and Wu identified a common pattern in atmospheric air circulations during many of the summers since 2012: Low-pressure systems would develop in the Arctic, forming clouds that kept temperatures cool by blocking sunlight and generating winds that spread out the remaining ice."

      The study discussed is available via open access at https://iopscience.iop.org/article/10.1088/1748-9326/abc047/pdf
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      Good article, but I don't think ASIF vets have been very surprised that the devastating 2012 freak-cyclone bottom-fell-out crash has not been repeated in the few years since.  Maybe Francis should call sark for additional insight on those jet stream patterns.

      What is more notable than the 2012 records lasting this long is that due to continuation of the long-term trends, both 2019 and 2020 approached the same melt levels as 2012 without input from freak events.  The GAC 2012 certainly made its mark, but because it used up some stored heat in doing so, the subsequent years saw a regression back to the trend line.  But now even the "new normal" levels are near (and going below in 2021?) what used to be freakishly low record-breaking levels less than a decade before.  Welcome to the future.  It didn't take very long to get here. 

       So that I can tell myself I'm not just kvetching, here is my attempt at an inspiring conclusion: - Do not go quietly into this dark night, talk about it, and please make sure that you, and folks in your social networks, vote climate wherever you live at every opportunity.  This insanity won't end until we make it end.  The infrastructure and other changes required to remake society (Make Earth Great Again?  :-\) is not only essential, it is the perfect opportunity to address many other interconnected social, economic and environmental problems.  To the guy who recently said "We can do this", I'll add "We HAVE to do this."
« Last Edit: Today at 01:45:06 AM by Glen Koehler »