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oren

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Re: Northern Hemisphere snow cover
« Reply #300 on: June 25, 2018, 03:18:26 AM »
Anyone here ever played with Google Earth Engine? (Satellite view time lapse starting in 1984) 
Never heard of it. Thanks for the link!

Rob Dekker

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Re: Northern Hemisphere snow cover
« Reply #301 on: June 26, 2018, 05:18:49 AM »
But also if you zoom out and look at the entirety of North America you can see a sharp reduction in snow cover.  Is this real snow loss or an illusion caused by enhanced satellite imagery? Watch for several loops, notice how the snow snaps back when it returns to 1984.

https://earthengine.google.com/timelapse/#v=68.21841,-109.73974,1.673,latLng&t=0.14

Thanks for that Google Earthengine site. That's a really cool tool.

Regarding the disappearing land snow cover since 1984, I think it is real.
Rutgers snow lab shows a remarkable decline for the month of June over the decades :
https://climate.rutgers.edu/snowcover/chart_anom.php?ui_set=1&ui_region=nhland&ui_month=6
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Daniel B.

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Re: Northern Hemisphere snow cover
« Reply #302 on: June 26, 2018, 07:29:42 PM »

bbr2314

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Re: Northern Hemisphere snow cover
« Reply #303 on: June 30, 2018, 12:38:54 AM »
Still snowing in Quebec!


Brigantine

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Re: Northern Hemisphere snow cover
« Reply #304 on: June 30, 2018, 01:05:26 AM »
Still snowing in Quebec!

The subtle difference between "it is forecast to snow 10 days (!) from now" and "it is currently snowing"
(like Newfoundland 4 days ago)

10 day forecasts come with extra salt.

Meanwhile snow cover is starting to blink out on Baffin Island - in the Western end and in a spot to the west of Cumberland Sound. Victoria Island is mostly snow free now. Summer has arrived in the CAA.

gerontocrat

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Re: Northern Hemisphere snow cover
« Reply #305 on: July 01, 2018, 11:31:19 AM »
https://www.ccin.ca/ccw/snow/current

Sorry, but methinks "snowmageddon" is postponed, at least until next year. The new ice age will have to wait.

The attached map shows there is snow still lying here and there much later than usual, but mostly only 5-10 cm depth.

The North America extent and SWE graphs also show higher extent and SWE than average, but nothing like they were earlier in the year.
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bbr2314

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Re: Northern Hemisphere snow cover
« Reply #306 on: July 01, 2018, 04:57:46 PM »
https://www.ccin.ca/ccw/snow/current

Sorry, but methinks "snowmageddon" is postponed, at least until next year. The new ice age will have to wait.

The attached map shows there is snow still lying here and there much later than usual, but mostly only 5-10 cm depth.

The North America extent and SWE graphs also show higher extent and SWE than average, but nothing like they were earlier in the year.
??? We are already dealing with catastrophic impacts. Greenland is also still whiter than normal. As are the Himalayas / elsewhere. A limited area at peak insolation is as impactful as a broad area at polar night.

I agree that Quebec etc is not yet re-glaciating but parts are still under 1M+ of cover. We may not have to wait more than another few years for coverage to make it through August. I would classify our current situation as "snowmaggedon" even if it isn't yet at the stage of glacial advance over wide regions.

Here is 2018 versus 2012, March to May. Look at the North Atlantic! And the North Pacific. They are now getting worse on both ends in tandem.

Another interesting thing to note is the attached comparison of 2014 to 2012. It looks remarkably similar to 2018. If you roll that year forward, the winter featured extremely severe cold across many regions, roughly correlated with Jan-May anomalies.

Versus 2014, 2018 has been substantially colder across the areas S of Kara. And Kara itself. I would think combined with the precedent over N America this portends an extremely and brutally cold and snowy winter across much of Eurasia and North America.

It may also mean that the Bering will not refreeze much at all in the winter of 2018-19!

jai mitchell

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Re: Northern Hemisphere snow cover
« Reply #307 on: July 01, 2018, 05:20:29 PM »
I agree that Quebec etc is not yet re-glaciating but parts are still under 1M+ of cover. We may not have to wait more than another few years for coverage to make it through August. I would classify our current situation as "snowmaggedon" even if it isn't yet at the stage of glacial advance over wide regions.

 ??? ??? ??? ??? ???


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bbr2314

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Re: Northern Hemisphere snow cover
« Reply #308 on: July 01, 2018, 05:56:21 PM »
I agree that Quebec etc is not yet re-glaciating but parts are still under 1M+ of cover. We may not have to wait more than another few years for coverage to make it through August. I would classify our current situation as "snowmaggedon" even if it isn't yet at the stage of glacial advance over wide regions.

 ??? ??? ??? ??? ???
Quebec City is not all of Quebec FYI.


Alexander555

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Re: Northern Hemisphere snow cover
« Reply #309 on: July 01, 2018, 07:15:00 PM »
In volume it can not be that much, if this pic is correct. But it shows how much meltwater entered the sea in just 14 days. From half way April until the start of May, that's like 800 km3. Normaly it takes 2 months to unload that volume.

Is there any data about the temperature of the water in the rivers in Canada ? It's getting hot there in the next weeks, and there is some rain. That should give the opposite situation, compared to the meltwater from last months.
« Last Edit: July 01, 2018, 07:27:50 PM by Alexander555 »

bbr2314

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Re: Northern Hemisphere snow cover
« Reply #310 on: July 01, 2018, 07:19:47 PM »
In volume it can not be that much, if this pic is correct. But it shows how much meltwater entered the sea in just 14 days. From half way April until the start of may, that's like 800 km3. Normaly it takes 2 months to unload that volume.

Is there any data about the temperature of the water in the rivers in Canada ? It's getting hot there in the next weeks, and there is some rain. That should give the opposite situation, compared to the meltwater from last months.
I would say NATL anomalies are a reasonable proxy. For now, everything is frigid.


oren

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Re: Northern Hemisphere snow cover
« Reply #311 on: July 01, 2018, 07:33:03 PM »
I agree that Quebec etc is not yet re-glaciating but parts are still under 1M+ of cover. We may not have to wait more than another few years for coverage to make it through August. I would classify our current situation as "snowmaggedon" even if it isn't yet at the stage of glacial advance over wide regions.

 ??? ??? ??? ??? ???
Quebec City is not all of Quebec FYI.
Seriously, snow melt-out dates have been less than 2 weeks late compared to normal, and not far from normal variability. The locations of current Quebec snow are not even where the snow depth anomalies have been concentrated in April, all those areas have melted a long time ago. Nothing suggests pending glaciation. Nothing.

jai mitchell

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Re: Northern Hemisphere snow cover
« Reply #312 on: July 01, 2018, 09:11:41 PM »
I agree that Quebec etc is not yet re-glaciating but parts are still under 1M+ of cover. We may not have to wait more than another few years for coverage to make it through August. I would classify our current situation as "snowmaggedon" even if it isn't yet at the stage of glacial advance over wide regions.

 ??? ??? ??? ??? ???
Quebec City is not all of Quebec FYI.
Seriously, snow melt-out dates have been less than 2 weeks late compared to normal, and not far from normal variability. The locations of current Quebec snow are not even where the snow depth anomalies have been concentrated in April, all those areas have melted a long time ago. Nothing suggests pending glaciation. Nothing.

We prevented pending glaciation with the advent of early human agriculture in 5,000 B.C.E. and especially with rice cultivation in 3,000 B.C.E.  whose absence would have produced glaciation conditions forming around 0 A.D. and would have certainly taken hold by the mid 1800's. 

We won't see another ice age for at least 200,000 years and probably longer.

much much much longer.

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jai mitchell

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Re: Northern Hemisphere snow cover
« Reply #313 on: July 01, 2018, 09:17:52 PM »
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Rob Dekker

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Re: Northern Hemisphere snow cover
« Reply #314 on: July 04, 2018, 08:26:05 AM »
Rutgers published the June numbers for Northern Hemisphere land snow cover.
It's still higher than most of the past 10 years, but significantly below the 'average' number recorded in May.

The take-away message : A lot of snow melted in June.

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Niall Dollard

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Re: Northern Hemisphere snow cover
« Reply #315 on: July 04, 2018, 06:36:55 PM »
The Rutgers figure for June was 7.84 million km2. That is a departure of -1.58 million below the 1981-2010 mean.

There was more snow than usual over parts of the far east of Russia (Chukotka and Kamchatka) and northern Quebec but less than normal over western and northern Canada and north central Siberia.

Chart showing the monthly anomalies 2016 -2018 attached. It is proving difficult to get a positive anomaly during the summer months.

gerontocrat

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Re: Northern Hemisphere snow cover
« Reply #316 on: July 05, 2018, 11:02:41 AM »
I think this is my last post until it starts snowing again. As expected, despite the massive
winter / spring snowfall, the snow melted - just a bit late, is all.

https://www.ccin.ca/ccw/snow/current
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Rob Dekker

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Re: Northern Hemisphere snow cover
« Reply #317 on: July 07, 2018, 05:01:55 AM »
Most of you will know that since 2013, I use I use the "whiteness" of the Arctic in June as a predictor for how much ice will melt out between June and September.

http://neven1.typepad.com/blog/2013/07/problematic-predictions-2.html

Specifically, I use three variables to make this prediction :
- Land snow cover in June
- Ice 'area' in June
- (Extent - Area) in June, which represents the amount of 'water' in the ice pack in June.

A combination of these variables, each one of which affects the 'albedo' of the Northern Hemisphere, represents how much solar energy gets absorbed by the Northern Hemisphere in summer, and this correlates remarkably well with September sea ice cover.

Details of this method is described in one of my entries into Arcus Sea Ice Prediction Network :

https://www.arcus.org/files/sio/25738/sio-2016-july_dekker.pdf

This year, land snow cover in June was quite high compared to recent years :



Also, ice 'area' is quite high in June (in between 2014 and 2015) and the ice is still fairly compact.

As a result, prediction for Sept 2018 September sea ice extent is quite high at 5.19 km2, with a standard deviation of 340 k km2.

My gut feeling this year tells me that this an upper bound, but it's fairly clear that given the past performance of this method, it is highly unlikely (less than 2.5% chance) that Sept 2018 will end up below 4.5 M km2.

Here is what this hind-cast method did for the past 26 years :



Comments and suggestions on this method are welcome in the "Re: Land snow cover effect on sea ice" thread :

https://forum.arctic-sea-ice.net/index.php/topic,292.msg162415.html#msg162415
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gerontocrat

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Re: Northern Hemisphere snow cover
« Reply #318 on: July 21, 2018, 08:48:39 PM »
"Alas, Snowmageddon, I knew you well"
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oren

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Re: Northern Hemisphere snow cover
« Reply #319 on: July 25, 2018, 08:30:52 AM »
Following a discussion on another thread, here's a summary of snow trends in the Alps. Hat tip to Magnamentis who provided the link.

Quote
Snowpack responds to climate change
Thanks to the long-term measurement data, we have been able to identify some clear trends. The last 30 years have seen very low levels of snow, particularly on the Swiss Plateau. The trend towards less snowy winters at most stations below 1300 m is statistically significant. The lower the altitude of the observation station, the more apparent the changes are. By contrast, above 2000 m the snow depths in midwinter (December to February) show no clear trend. The same is not true of snow cover duration: the vast majority of stations are seeing a clear reduction in the number of days with snow-covered ground, regardless of their altitude or location. The primary reason for this is earlier snow melt in the spring. The delay of snow onset in autumn is also a factor at lower-altitude stations. In addition, the annual maxima for snowfall and snow depths have tended to decline at all stations over recent decades.

https://www.slf.ch/en/snow/snow-and-climate-change.html

Tor Bejnar

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Re: Northern Hemisphere snow cover
« Reply #320 on: July 25, 2018, 03:13:18 PM »
Tamino recently did a post on Colorado, USA snow trends:
Global Warming: Let It Snow. The results of his inquiry would not be surprising to anybody who frequents these threads or his posts.
Quote
...
But 15 stations [in Colorado] show statistically significant rates of snow-out day, all of them trending earlier, and 15 reached significance for maximum SWE, all of them trending lower. This is not an accident. It’s the result of climate change. Man-made climate change.
...
SWE = snow water equivalent
Arctic ice is healthy for children and other living things.

Shared Humanity

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Re: Northern Hemisphere snow cover
« Reply #321 on: July 25, 2018, 04:10:08 PM »
Following a discussion on another thread, here's a summary of snow trends in the Alps. Hat tip to Magnamentis who provided the link.

Quote
Snowpack responds to climate change
Thanks to the long-term measurement data, we have been able to identify some clear trends. The last 30 years have seen very low levels of snow, particularly on the Swiss Plateau. The trend towards less snowy winters at most stations below 1300 m is statistically significant. The lower the altitude of the observation station, the more apparent the changes are. By contrast, above 2000 m the snow depths in midwinter (December to February) show no clear trend. The same is not true of snow cover duration: the vast majority of stations are seeing a clear reduction in the number of days with snow-covered ground, regardless of their altitude or location. The primary reason for this is earlier snow melt in the spring. The delay of snow onset in autumn is also a factor at lower-altitude stations. In addition, the annual maxima for snowfall and snow depths have tended to decline at all stations over recent decades.

https://www.slf.ch/en/snow/snow-and-climate-change.html

It would appear that, as the earth warms, we generally get less snow.  :)

crandles

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Re: Northern Hemisphere snow cover
« Reply #322 on: July 25, 2018, 04:12:29 PM »
It would appear that, as the earth warms, we generally get less snow.  :)

Or more melting  ;)

gerontocrat

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Re: Northern Hemisphere snow cover
« Reply #323 on: July 25, 2018, 08:51:53 PM »
Following a discussion on another thread, here's a summary of snow trends in the Alps. Hat tip to Magnamentis who provided the link.

Quote
Snowpack responds to climate change
Thanks to the long-term measurement data, we have been able to identify some clear trends. The last 30 years have seen very low levels of snow, particularly on the Swiss Plateau. The trend towards less snowy winters at most stations below 1300 m is statistically significant. The lower the altitude of the observation station, the more apparent the changes are. By contrast, above 2000 m the snow depths in midwinter (December to February) show no clear trend. The same is not true of snow cover duration: the vast majority of stations are seeing a clear reduction in the number of days with snow-covered ground, regardless of their altitude or location. The primary reason for this is earlier snow melt in the spring. The delay of snow onset in autumn is also a factor at lower-altitude stations. In addition, the annual maxima for snowfall and snow depths have tended to decline at all stations over recent decades.

https://www.slf.ch/en/snow/snow-and-climate-change.html

It would appear that, as the earth warms, we generally get less snow.  :)
On Environment Canada I found a mention of a study showing that there is more snow at very high latitudes, and less at lower latitudes, and the snowline is moving up the slopes of the mountains. Seems a logical progression to me as water vapour increasing as are air temperatures.
No comment from BBR yet?
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bbr2314

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Re: Northern Hemisphere snow cover
« Reply #324 on: July 25, 2018, 08:55:05 PM »
These studies do not include 2017 or 2018. It would be like a sea ice study that only went up to 2005. Inflection points matter but all these measurements compare to XX decades ago -- mostly meaningless. So I am not going to engage.

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Re: Northern Hemisphere snow cover
« Reply #325 on: July 26, 2018, 09:23:02 AM »
I think in the highest lattitudes there will be more snowfall, in other regions less. In the highest latitudes more evaporation will lead to more snow, in the lower latitudes the higher heat will reduce the area that is cold enough for snow and will cause more drought.

But that is not based on scientific field research, just some logical reasoning, which could make no sense at all

Tealight

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Re: Northern Hemisphere snow cover
« Reply #326 on: July 27, 2018, 03:13:21 AM »
I'm working on a simple (non-gridded) version of my AWP anomaly model for the Northern Hemisphere land cover in order to quantify the effect of the increased snow extent we had the last few springs. There will still be a continental breakdown of Eurasia, North America and Greenland because the Latitude changes differently on each for the same snow extent values.

What's definitely clear is that the most important months are May and June. The autumn does hardly matter because the solar intensity is too low. Overall there is of course a strong warming trend. 2017 causes a drop in the 5 year moving average, and 2018 doesn't make up for it. (until June)

Maybe I finish it sometime in August and will post a better description and analysis on my website.
https://sites.google.com/site/cryospherecomputing/awp

All snow extent data is from Rutgers University:
https://climate.rutgers.edu/snowcover/table_area.php?ui_set=2

Here are some preliminary Graphs for the whole Northern Hemisphere.
« Last Edit: July 27, 2018, 03:19:04 AM by Tealight »

bbr2314

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Re: Northern Hemisphere snow cover
« Reply #327 on: July 27, 2018, 03:16:13 AM »
I'm working on a simple (non-gridded) version of my AWP anomaly model for the Northern Hemisphere land cover in order to quantify the effect of the increased snow extent we had the last few springs. There will still be a continental breakdown of Eurasia, North America and Greenland because the Latitude changes differently on each for the same snow extent values.

What's definitely clear is that the most important months are May and June. The autumn does hardly matter because the solar intensity is too low. Overall there is of course a strong warming trend. 2017 causes a slight drop in the 5 year moving average, but 2018 is similar to recent years.

Maybe I finish it sometime in August and will post a better description and analysis on my website.
https://sites.google.com/site/cryospherecomputing/awp

All snow extent data is from Rutgers University:
https://climate.rutgers.edu/snowcover/table_area.php?ui_set=2

Here are some preliminary Graphs for the whole Northern Hemisphere.
Can you please plot the derivative? I think it may have more value to the sea ice than absolute as it is indicative of trend instead of gross anomaly.

gerontocrat

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Re: Northern Hemisphere snow cover
« Reply #328 on: July 27, 2018, 12:24:40 PM »
Interesting contrast between North America SWE and SCE at this fag-end of the snow year.

SWE approaching zero while SCE still a good bit higher than average. Must be a low average snow depth ? This is the reverse of the situation during the snowfall period especially in February to April.
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Shared Humanity

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Re: Northern Hemisphere snow cover
« Reply #329 on: July 27, 2018, 07:44:37 PM »
Interesting contrast between North America SWE and SCE at this fag-end of the snow year.

SWE approaching zero while SCE still a good bit higher than average. Must be a low average snow depth ? This is the reverse of the situation during the snowfall period especially in February to April.

Fresh recent snow in areas that had been snow free?

Alexander555

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Re: Northern Hemisphere snow cover
« Reply #330 on: July 27, 2018, 08:52:55 PM »
Tealight, what exactly is the 2th graph showing us ?

Tealight

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Re: Northern Hemisphere snow cover
« Reply #331 on: July 28, 2018, 01:42:58 AM »
Can you please plot the derivative? I think it may have more value to the sea ice than absolute as it is indicative of trend instead of gross anomaly.

I will make all data available soon and then everyone can create their own investigations and graphs. More useful for sea ice are probably sub-seasonal time-frames like March to June or September.

Tealight, what exactly is the 2th graph showing us ?

It shows the anomaly of the maximum possible absorbed solar energy assuming clear sky conditions. The only difference between years is the snow extent (albedo of the land surface)
By the way I set the snow free land albedo as 0.25, snow covered albedo as 0.6 for the continents and snow albedo on Greenland as 0.8. Different values would not change the ranking between years, only make the differences larger or smaller.

---------------------------

I don't think absolute energy numbers are very intuitive or does anyone here know how 180*10^21 Joule influence the earth over 100 million square kilometer and 365 days?

Alternatively the data can be presented in percent.

e.g. In 2012 the land absorbed 1.9% more and in 1985 2% less energy compared to the long term mean.

edit: the differences are actually a bit higher than that. It's just difficult to estimate a good latitude and incoming solar energy with a non-gridded model. At least for now this issue reduces the differences between years in my model.
« Last Edit: July 28, 2018, 01:58:19 AM by Tealight »

bbr2314

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Re: Northern Hemisphere snow cover
« Reply #332 on: July 30, 2018, 01:29:45 AM »
Though limited, extant cover should survive in Quebec well into August...!


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Re: Northern Hemisphere snow cover
« Reply #333 on: July 30, 2018, 04:38:37 AM »
I'm not sure about "well into August", but as of 29 July there is still snow according to NIC.

2018:


2017 also had just a speck, in the same place on Uganva peninsula:


2013 was in-between - there were several small specks: (The last one finally disappeared on August 2)
« Last Edit: July 30, 2018, 04:47:15 AM by Brigantine »

Niall Dollard

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Re: Northern Hemisphere snow cover
« Reply #334 on: July 30, 2018, 06:18:56 PM »
By the way I set the snow free land albedo as 0.25, snow covered albedo as 0.6 for the continents and snow albedo on Greenland as 0.8.

I was just comparing the western section of the Greenland Ice Sheet on Worldview and noticed this time last year the surface at the edges of the sheet were a lot more grey coloured than this year. Similar grey edges 2017 vs whiter edges 2018 were observed at other parts of the Greenland sheet also.

I am not sure whether this is down to enhanced July melt conditions last year vs this year (although the NSIDC graph does not show much difference between the two years) or whether it is smoke/dust/particulate related or maybe even different Worldview visual processing between the two years ?
« Last Edit: July 30, 2018, 06:46:57 PM by Niall Dollard »

gerontocrat

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Re: Northern Hemisphere snow cover
« Reply #335 on: July 31, 2018, 12:12:55 PM »
North America Snow Cover Extent at 30 July is still more than 1 standard deviation above the average, just about exactly the same as at the beginning of the snow year (1st August 2017). i.e. as near as makes no odds, last year's snow year ended up in the same place as this year. Snow Water Equivalent (Km3) is minimal.

ps:- And although Hudson bay was late and slow to melt (and logic says that must be partly due to loads of snow), area is now in the same place as just about every year, i.e. well under 10% of maximum. At an average latitude around 60o North, plenty of time for this very shallow sea to warm up per usual before the freeze.

https://www.ccin.ca/ccw/snow/current
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gerontocrat

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Re: Northern Hemisphere snow cover
« Reply #336 on: August 01, 2018, 01:50:30 PM »
Environment Canada has a snowfall year of August to July - so yesterday was the end of the 2017-
18 year. Attached are the July 31 graphs.

By winter spring 2018-19 it looks like an El Nino will be in place. It will be interesting to see if that has an effect of snowfall (and to see how bbr2314's snowmageddon develops). Apart from a peek now and then to see how much more snow melts during August,  I guess I will put this thread into sleep mode until at least mid-September.
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)

bbr2314

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Re: Northern Hemisphere snow cover
« Reply #337 on: August 07, 2018, 01:15:24 AM »
Oh la la

L'hiver approche rapidement

Il neige a Quebec, peut etre la neige dans la nord vivre sur tous l'ete? Maintenant c'est vraiment possible!


colchonero

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Re: Northern Hemisphere snow cover
« Reply #338 on: August 07, 2018, 02:39:38 AM »
Oh la la

L'hiver approche rapidement

Il neige a Quebec, peut etre la neige dans la nord vivre sur tous l'ete? Maintenant c'est vraiment possible!




Bbr are you French? And why aren't you ;D? No man, just kidding about some grammar there, nice post and we'll see if the forecast will hold in the next couple of days.

bbr2314

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Re: Northern Hemisphere snow cover
« Reply #339 on: August 07, 2018, 03:07:35 AM »
Oh la la

L'hiver approche rapidement

Il neige a Quebec, peut etre la neige dans la nord vivre sur tous l'ete? Maintenant c'est vraiment possible!




Bbr are you French? And why aren't you ;D? No man, just kidding about some grammar there, nice post and we'll see if the forecast will hold in the next couple of days.
Je parle parfait franglais -- mon francais est seulement moyenne, desolee :(

bbr2314

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Re: Northern Hemisphere snow cover
« Reply #340 on: August 07, 2018, 12:13:35 PM »
EURO wants winter to begin early across much of the Shield while the Arctic absolutely torches thanks to all the latent heat release from severe tropical cyclones in the PAC:


Niall Dollard

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Re: Northern Hemisphere snow cover
« Reply #341 on: August 08, 2018, 07:22:06 PM »
Rutgers NH snow cover figure for July was 3.01 million km2.

That is a negative departure of -0.66 million km2.

This is the third monthly negative departure in a row, but the departure for July was not as big as that of July 2016.

Negative departures were over Kamchatka, north tip of Siberia, western Canada and the southern CAA

Positive departures were over southern Baffin, NE Quebec and the north CAA.

Shared Humanity

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Re: Northern Hemisphere snow cover
« Reply #342 on: August 09, 2018, 05:02:18 AM »
Puts away parka and snow shoes.

bbr2314

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Re: Northern Hemisphere snow cover
« Reply #343 on: August 09, 2018, 02:01:39 PM »
Winter is cominggggg!  ;D







Repeated and generally sustained cold should mean that snows will once again be falling fairly consistently across higher terrain. Also, Foxe Basin's forecast is C-O-L-D. I wonder if much of its ice is retained? Conditions for melt through D10 look generally unfavorable or actually positive for snowfall.

bbr2314

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Re: Northern Hemisphere snow cover
« Reply #344 on: August 12, 2018, 10:16:02 PM »
I think it may be time for a new thread on the 2018-19 winter and what I think will unfold. I have seen some discussion amongst friends that the Gulf Stream is either now failing more completely or shifting modes substantially (i.e., shifting in the same way that FRAM export is now close to 0 because all the ice melts out before it can get exported).

This link contains charts that are quite fascinating in illustrating how severe and unprecedented this past April was across much of the US. Interestingly, while other cool periods in winter are characterized by lower maxes than mins vs. normal (usually), this past April saw lower MINIMUMS than maximums vs. normal.

In fact, this past April was the *coldest on record* for minimums across a vast swath of Middle America (as well as absolute averages over a smaller portion).

https://www.esrl.noaa.gov/psd/cgi-bin/data/timeseries/timeseries1.pl


bbr2314

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Re: Northern Hemisphere snow cover
« Reply #345 on: August 13, 2018, 01:02:15 AM »
First run of the GFS with extremely substantial totals in Quebec and falls across areas of Canada S of Nunavut:


bbr2314

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Re: Northern Hemisphere snow cover
« Reply #346 on: August 16, 2018, 06:40:27 PM »
Q: What do you call it when snow survives the summer across certain areas where it normally doesn't?

A: Re-glaciation!

New GFS, CMC, and EURO (shown below) are all showing sustained falls now occurring through D10, not without intermittent melt, but whatever melt there is will be overwhelmed by feet of new snow. It's happening (?)



bbr2314

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Re: Northern Hemisphere snow cover
« Reply #347 on: August 16, 2018, 08:52:13 PM »
The 12z EURO appears much more aggressive with re-establishing the cryosphere across the Canadian shield, I suspect this is due to all the heat in the PAC front and Laptev.

850s are off and on below 0 until 168 when first major-ish blast comes through.



By 216 cold is loading into NWT and Yukon. I suspect EURO is also being too progressive with removing cold from Quebec (as it has been most months this year). Winter is just about here for much of the Canadian Shield...



It looks like the +500MB anoms over Pac front / Laptev have tightened the persistent -500MB vortex over Greenland that has dominated this summer's weather, and as a result, it will continue firing rapid blasts of -GAK airmasses into NW Canada / Quebec.



Snow-liquid equivalent through hr 204


Tor Bejnar

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Re: Northern Hemisphere snow cover
« Reply #348 on: August 16, 2018, 08:52:43 PM »
"A glacier is a large, long-lasting mass of ice found on land that moves because of gravity." (link)  A snowfield is not a glacier.  Perennial ice that does not move is not a glacier.  If you want to read about a new glacier, look to Mt. St. Helens' Crater Glacier.
Arctic ice is healthy for children and other living things.

bbr2314

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Re: Northern Hemisphere snow cover
« Reply #349 on: August 16, 2018, 09:32:34 PM »
"A glacier is a large, long-lasting mass of ice found on land that moves because of gravity." (link)  A snowfield is not a glacier.  Perennial ice that does not move is not a glacier.  If you want to read about a new glacier, look to Mt. St. Helens' Crater Glacier.
I said re-glaciation has begun, not that it was a glacier. We will have to wait a few more years for perennial snowcover to result in "glaciers" but the process "re-glaciation" is now underway, IMO.

It should be noted that the maps for climate at -1C vs today show "glacier accumulation zones" covering precisely the areas that are now seemingly seeing perennial snowcover.



While temps in NRN Quebec were WAY warmer than normal during winter, so far this summer (when warmth vs. normal is relative to melt, instead of resulting in +++snowfall), temps have been way below normal. In fact, since 6/1, large swaths of Quebec have been up to -2.5C vs. normal.

I think people are conflating what is necessary for perennial snowcover to exist. We need SUMMERTIME temps of -1C or lower vs. averages for perennial snowcover in the highest regions, and from -3C or lower in the lower elevations of Quebec. The only critical period for negative anomalies is in between the start of melt and the start of new snows -- and the longer melt is held off, the quicker new snows begin falling due to remaining extant cover and residual sea ice in the vicinity (i.e. Foxe Basin still has substantial thick ice). If wintertime temps average -20C, a +10C three-month departure from Dec to Feb only serves to allow more moisture and thicken the snowpack. On the otherhand, if that +++wintertime departure is matched by a -2 or -3C JJA anomaly, we see snows remain extant through summer and re-glaciation begins very rapidly.

« Last Edit: August 16, 2018, 09:40:12 PM by bbr2314 »