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Author Topic: Northern Hemisphere snow cover  (Read 8962 times)

Neven

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Northern Hemisphere snow cover
« on: March 07, 2013, 11:24:11 PM »
Okay, so I added 'snow cover' to this board's subtitle, just so I would have somewhere to put this. Al Rodger wrote a great guest piece last summer for the ASIB explaining why snow cover is important, and how its summer decline is at least as important as that of Arctic sea ice.

This year's February anomaly comes in lower than the previous three years:



Graphs comes from Rutgers University Global Snow Lab.
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Juan C. García

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Re: Northern Hemisphere snow cover
« Reply #1 on: March 12, 2013, 03:16:36 AM »
It will be interesting to see if we will have a new snow cover anomaly record at June/2013. The last five years were of impresive anomalies and of course, it has a relation with the permafrost and methane emissions, even that I would say that there is not good measurement of methane emssions related to the thawing of the permafrost.

(image also from Rutgers University Global Snow Lab:
http://climate.rutgers.edu/snowcover/chart_anom.php?ui_set=1&ui_region=nhland&ui_month=6
Which is the best answer to Sep-2012 ASI lost (compared to 1979-2000)?
50% [NSIDC Extent] or
73% [PIOMAS Volume]

Volume is harder to measure than extent, but 3-dimensional space is real, 2D's hide ~50% thickness gone.
-> IPCC/NSIDC trends [based on extent] underestimate the real speed of ASI lost.

ggelsrinc

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Re: Northern Hemisphere snow cover
« Reply #2 on: April 02, 2013, 03:49:59 AM »
It will be interesting to see if we will have a new snow cover anomaly record at June/2013. The last five years were of impresive anomalies and of course, it has a relation with the permafrost and methane emissions, even that I would say that there is not good measurement of methane emssions related to the thawing of the permafrost.

(image also from Rutgers University Global Snow Lab:
http://climate.rutgers.edu/snowcover/chart_anom.php?ui_set=1&ui_region=nhland&ui_month=6

I've been using the same chart to paint a picture of what will happen if this trend continues. The June anomaly doesn't have to increase, it's magnitude is already at three times the area of Greenland or the remaining arctic sea ice at minimum. I picture a large NH area having air masses warmed by the albedo change during the most direct times of sunlight. I think those Greenland melts are going to become much more usual and hope it will motivate governments to show their proper concern about climate change. Afterall, Rip Van Winkle only slept for 20 years.

Neven

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Re: Northern Hemisphere snow cover
« Reply #3 on: April 07, 2013, 12:09:10 PM »
March ended up a positive anomaly:



It will be interesting to see what April does, no positive anomaly in 9 years:

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ChrisReynolds

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Re: Northern Hemisphere snow cover
« Reply #4 on: April 07, 2013, 12:13:35 PM »
Eurasian snow retreat in May is leading to warming and this early start to the melt season is occurring over major areas of permafrost. That latter point is missing from my blog post, but I thought my readers would be all too aware.
http://dosbat.blogspot.co.uk/2013/03/eurasian-snow-cover-and-atmospheric.html

crandles

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Re: Northern Hemisphere snow cover
« Reply #5 on: April 07, 2013, 01:36:42 PM »
March ended up a positive anomaly:

I am sure that is true but at the moment graph says it runs to 2012. I guess that is one way to appear to be first to post on release of graph. Or did graph update and then revert?

Neven

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Re: Northern Hemisphere snow cover
« Reply #6 on: April 07, 2013, 08:47:31 PM »
I am sure that is true but at the moment graph says it runs to 2012. I guess that is one way to appear to be first to post on release of graph. Or did graph update and then revert?

I just looked at the bars and it looked to me like the 2013 bar was there. At the top it says 1967-2013 as well. We're talking about the March bar graph, right?
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crandles

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Re: Northern Hemisphere snow cover
« Reply #7 on: April 07, 2013, 09:17:41 PM »
This is what I see above and when I go to site and control-F5.



Says 1967-2012 March at top and last bar is negative.

Control-F5 should clear any cache and download it again shouldn't it? Am I looking in wrong place? I'm confused.  :(

Edit: sorry ignore me. Control-F5 didn't make a difference but tried a simple reload of the page and it worked. Shows above too now.
« Last Edit: April 07, 2013, 09:24:00 PM by crandles »

Artful Dodger

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Re: Northern Hemisphere snow cover
« Reply #8 on: April 08, 2013, 11:06:43 AM »
Snow cover over sea ice is an important, under-reported measure during the dark cold Arctic Winter.

Snow is an excellent thermal insulator. When snow covered, sea ice attains thermodynamic equilibrium with the atmosphere when it is much thinner than bare sea ice. Alternatively, snow-covered sea ice will grow to the same thickness only if the atmosphere is much colder.

We know from the 80N temperature plot this Winter that the atmosphere WAS not much colder, in fact it was warmer than normal except for the period spanning Feb/Mar with high winds, which tends to scour the surface of warm air by mixing in higher colder layers.

Additionally, the Feb/Mar break-up event itself argues that the sea was not as strong as in past years, which may indicate that it's thickness was reduced.

Two important results will come out in May. First will be the report from NASA Icebridge, which flew at least two missions over the Beaufort sea in late March. Second is the scheduled public release of AMSR2 Level-2 data, which includes 'Snow-over-sea-ice' data.

Looking forward to this analysis since I think it will be quite useful for prediction as the 2013 melt season progresses.
Cheers!
Lodger

Artful Dodger

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Re: Northern Hemisphere snow cover
« Reply #9 on: April 08, 2013, 12:04:06 PM »
...the period spanning Feb/Mar with high winds, which tends to scour the surface of warm air by mixing in higher colder layers.
Since this is a related topic, I want to highlight some recently published science:

Sterk, H. A. M., G. J. Steeneveld, and A. A. M. Holtslag. "The role of snow‐surface coupling, radiation, and turbulent mixing in modeling a stable boundary layer over Arctic sea ice." Journal of Geophysical Research: Atmospheres (2013).

There is also a freely-available PDF for interested readers.

Now, an excerpt from the Abstract:

Keywords:
  • Arctic stable boundary layer;
  • modeling;
  • GABLS;
  • turbulent mixing;
  • surface coupling;
  • radiation
Results indicate a shift in process significance for different wind regimes. For low wind regimes, the model sensitivity is larger for surface coupling and radiation, while for high wind speeds, the largest sensitivity is found for the turbulent mixing process. An interesting non-linear feature was found for turbulent mixing for frequently occurring wind speeds and low wind speed cases, where the 2 m temperature increases for decreased amounts of mixing.

So it seemly likely that decreased 80N surface temps during Feb/Mar 2013 were the result of enhanced wind-mixing of the surface layer with colder higher air.
« Last Edit: April 08, 2013, 12:11:19 PM by Artful Dodger »
Cheers!
Lodger

Apocalypse4Real

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Re: Northern Hemisphere snow cover
« Reply #10 on: May 26, 2013, 07:28:25 PM »
The Siberian snow drought is apparent in the Rutgers and Drought Monitor imagery.

Attached are the Rutgers Snow and Departure from norm for May 25 2013, and the Drought Monitor for Siberia as of May 16, 2013.

Very warm air continues to flow north over Siberia for the next 5 days.

Apocalypse4Real

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Re: Northern Hemisphere snow cover
« Reply #11 on: May 26, 2013, 07:56:04 PM »
Here are two better perspectives for the UCL drought data, that help make the snow drought glaringly obvious for the Northern Hemisphere:

Attached are the Euro-Asia, North America and Arctic 90 day drought levels as of May 16 2013

Neven

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Re: Northern Hemisphere snow cover
« Reply #12 on: July 08, 2015, 07:56:03 AM »
Nightvid Cole posted in a separate thread:

NH snow cover for June is second lowest on record

See chart. (Note: This only includes land snow, not snow on sea ice, so this is a separate measurement from the very low June snow seen on sea ice this year).
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Jim Hunt

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Re: Northern Hemisphere snow cover
« Reply #13 on: July 08, 2015, 09:50:56 AM »
Certain "skeptical" sorts would have us believe otherwise:

http://GreatWhiteCon.info/2015/06/alaska-may-snow-cover-at-record-low-levels/

Nightvid & Vergent get a mention!
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

Niall Dollard

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Re: Northern Hemisphere snow cover
« Reply #14 on: October 19, 2017, 09:26:50 PM »
I could n't see a more recent thread, although I am sure NH snow cover crops up regularly in other threads so I've resurrected this one.

Kind of surprising there is n't more about this topic. As the NSIDC put it "in terms of area, snow cover is the largest single component of the cryosphere, covering an average of about 46 million square kilometers (about 17.8 million square miles) of Earth's surface each year ."

Interesting to look back on some of the posts from the start of this thread or indeed prior to that in this blog five years ago from Neven.

In recent years the lack of snow cover was especially evident in the crucial late spring/early summer period.

"At the height of this summer's melt, 2012 was 8.5 million sq kilometres ahead of the 1972-1979 average. This is a full month advance in the melt over a 27 year period."

So here is an update from Rutgers University. 2017 is turning out to be a snowy year. I've put it alongside 2016 for comparison. 2016 was much like the years prior showing serious decline in snow cover. 2017 has seen quite a turnaround. Most months so far with positive anomalies and the negative ones were only slight.

The question is, are we seeing a shift in the climate of the Arctic, a change from a once desert climate to a more snowy one. Will the warming world lead to more snow in the Arctic ? Or is this recent change only a blip ? 


Shared Humanity

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Re: Northern Hemisphere snow cover
« Reply #15 on: November 04, 2017, 04:35:42 PM »
I could n't see a more recent thread, although I am sure NH snow cover crops up regularly in other threads so I've resurrected this one.



I know you have a particular interest in this topic (I find it interesting myself as increased precipitation is an expected response of climate change.) Posting here is the right thing to do and, if you continue to use this thread, it will remain active and draw more visitors.

Question....hasn't there been a trend of increased earlier NH snowfall over the past decade? I remember someone posting this but cannot remember where.

Niall Dollard

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Re: Northern Hemisphere snow cover
« Reply #16 on: November 14, 2017, 06:20:27 PM »

Question....hasn't there been a trend of increased earlier NH snowfall over the past decade? I remember someone posting this but cannot remember where.

All the months from September through to January show a positive trend for monthly northern hemisphere snow cover (1967-2016). You can check out the plots here for each month.

For the other months there is a negative trend. This year continues to see mostly positive anomalies.

For October 2017 the NH snowcover was 21.17 million sq km. (+3.63  above the 1981-2010 norm).

A little bit less than October 2016. This being the first month that 2016 had higher anomaly than 2017.