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Author Topic: Snow Cover changes on regional scale  (Read 545 times)

Tealight

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Snow Cover changes on regional scale
« on: January 07, 2019, 01:25:37 AM »
I finished calculating regional snow extent data and will post my analysis here. The main snow cover thread doesn't quite fit for this detailed long term analysis. At the moment all data is still in one long list, but after formatting we can graph things like snow extent for region x in month y. I attached a map showing all regions and an example for Greenlands snow extent.

Eventually regional graphs should also get daily updates on my main snow cover webpage
https://sites.google.com/site/cryospherecomputing/snow-cover

Data Download (csv & formatted ExcelSheet)
https://github.com/NicoSun/CryosphereComputing/tree/master/ScienceData/Snow_Cover_Regional

« Last Edit: January 08, 2019, 02:21:01 PM by Tealight »

Tor Bejnar

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Re: Snow Cover changes on regional scale
« Reply #1 on: January 07, 2019, 05:29:44 AM »
I note the two lowest August Greenland snow extent years matche the two lowest August Arctic sea ice extent years.
Arctic ice is healthy for children and other living things.

Tealight

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Re: Snow Cover changes on regional scale
« Reply #2 on: January 08, 2019, 02:37:53 PM »
The data is now available as a formatted Excel sheet through the Link in the first post. I try to post 2-3 regions every day until we covered all of them.

Today we continue the northern regions with northern Canada and Alaska. They feature a pattern I've seen in several northern regions. Early summer snow cover was lowest in the 2010-2012 region and increases moderately for earlier years and slightly later years.

Tealight

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Re: Snow Cover changes on regional scale
« Reply #3 on: January 09, 2019, 11:21:42 PM »
Today we continue with Canada. This post is about the Canadian Rockies and Central Canada. The next one is exclusive to eastern Canada. Check the region map in the first post for the exact boundaries.

For the Rockies May, June and October seem to have a consistent downward tend in snow cover over the last 20 years. The other months are very close to either the maximum extent or to the minimum extent. Only November has a very slightly positive trend in snow cover.

In Spring/Autum snow cover in Central Canada is highly variable from year to year. However October and November show a very clear upwards tend. So the data is confirming the theory that the higher atmospheric moisture from an increasingly ice free Arctic causes more snow cover in the autumn.

Tealight

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Re: Snow Cover changes on regional scale
« Reply #4 on: January 09, 2019, 11:40:55 PM »
Eastern Canada doesn't have a downwards trend during Spring. Instead it's positive like in the autumn. The theory here is that eastern Canada receives so much more snowfall that it offsets any increased snow melt during spring. See the Northern Hemisphere snow cover thread for discussion, maps & graphs (around post 200).

snow cover trend per month
April: slight increase
May: clear increase
June: neutral
July: slight increase
Aug: None
Sep: clear increase (although at very low level)
Oct: clear increase
Nov: clear increase
« Last Edit: January 09, 2019, 11:51:59 PM by Tealight »

Tealight

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Re: Snow Cover changes on regional scale
« Reply #5 on: January 11, 2019, 02:31:58 AM »
Today we continue with the Arctic region with Siberia. This post is about the Eastern and Central Siberia. The next one is exclusive to western Siberia. Check the region map in the first post for the exact boundaries.

Like the Arctic in Northern America early summer snow cover was lowest in the 2010-2012 region and increases for earlier years and later years. For eastern Siberia this is most pronounced in June and for Central Siberia in May.

Autumn Snow Cover shows no significant trend for eastern Siberia, possibly due to almost complete coverage by the end of October. Central Siberia experiences a slight increase in October and November snow cover.

Tealight

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Re: Snow Cover changes on regional scale
« Reply #6 on: January 11, 2019, 02:32:41 AM »
West Siberia varies more noticably from year, but has again an early summer low point around 2010-2012. October shows the typical long-term autumn increase in snow cover which we have observed in other regions. November only has a very small increase due to the large year to year variability.
« Last Edit: January 11, 2019, 02:46:30 AM by Tealight »

Tealight

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Re: Snow Cover changes on regional scale
« Reply #7 on: January 12, 2019, 02:26:01 PM »
Today we complete the Arctic region with Eastern Europe and Scandinavia.

Both regions are heavily influenced by the North Atlantic and snow extent varies considerably from year to year. Neither follows the typical spring decrease and autumn increase trend of other Arctic regions. Overall Eastern Europe experiences a modest decline in snow cover over most month, but as 2017 shows new record high snow cover (for the last 20 year period) is also possible.

The only months with a trend in Scandinavia are February and October showing a slight increase and June with a slight decrease.

Tealight

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Re: Snow Cover changes on regional scale
« Reply #8 on: January 12, 2019, 03:06:32 PM »
We finish the Arctic regions with the mean extent over the whole year to see when each region starts to melt and at what rate. For example Alaska melt starts early at the end of April, but takes until the end of June. In contrast Eastern Siberia doesn't start until mid May, but also finishes at the end of June.

The 2000s and 2010s mean snow extents of Alaska and Eastern Canada show the magnitude of low spring snow cover or high autumn snow cover compared to the whole year.