2014 Northern Hemisphere Snow Cover Thread

[The_Global_Warmer]

Based on the models. It looks like Siberia will see an increase in snow cover before an explosion of snow cover towards the end of Sept into early Oct.

While the NA side side sees new snow limited to the Mtn ranges out NW around Alaska with this side getting the warmth.

[Sundog]

Is the negative snow anomaly impacted by a reduction of normal sea ice levels? In other words do they count the missing sea ice as a reduction in snow cover, therefore creating a perpetual negative anomaly every summer?

[The_Global_Warmer]

No it's not.  Not on the Ruttger's snow charts.

 

 

The snow cover anomaly in Spring comes regardless of weather pattern.  It's probably driven by GHG forcing.  But in Siberia may also be enhanced by thawing of the permafrost below the ice and extra heat being able to go to melting the bottom of the snow rather than warm the ground below to a higher freezing point. 

 

 

Very small subtle changes in incoming energy from whatever source can have a major effect on snow cover because we are talking about like 3" lasting a few more weeks vs it not. 

 

On top of that partial snow cover is still snow cover until a certain degree. It's not 100 percent of each pixel.  So again the actual amount of energy change when it comes to April-June as you go North in Latitude is not much for major changes in snow cover.

 

 

Another feedback is more snow fall = more water = more water on top of hardened snow pack = more heat absorption = faster melting.  Or again that snow water leaks to the frozen surface and melts the bottom of the ice and helps unthaw the top of the permafrost.

 

As long as GHG forcing increases or is how it is now and the Suns energy is increasing during Spring naturally its one big feedback for snow cover melting off faster.

[Jonger]

Sundog, its anomaly percentage.... So 2-3% of virtually nothing is virtually nothing. 2-3% in the winter is a big deal though.

Its splitting hairs.

[Geos]

Barrow, AK is becoming snow covered.

 

[tacoman25]

Sundog, its anomaly percentage.... So 2-3% of virtually nothing is virtually nothing. 2-3% in the winter is a big deal though. Its splitting hairs.

 

Yes, exactly. Snow cover anomaly in the winter (or even late fall and early spring) is much more significant than summer, when there is hardly any snow cover anyway.

[SVT450R]

Is the negative snow anomaly impacted by a reduction of normal sea ice levels? In other words do they count the missing sea ice as a reduction in snow cover, therefore creating a perpetual negative anomaly every summer?[/

quote]

The chart I posted above does include sea ice snow cover but they also do have one for NH land which isn't working ATM.

[skierinvermont]

Remember folks, these anomalies are on the 1995-2009 baseline which was very warm and low snow. For gauging long-term changes in snowcover, a longer and/or older baseline would be more appropriate. 

 

On a 1971-2000 baseline, year to date we have averaged close to -1 million sq/km, which is better than recent years but still below the 1971-2000 average. Older, colder baselines would of course show an even more negative departure. 

[skierinvermont]

Sundog, its anomaly percentage.... So 2-3% of virtually nothing is virtually nothing. 2-3% in the winter is a big deal though. Its splitting hairs.

 

This is false, tacoman and Jonger.

 

The "Anomalies %" is actually referring to the anomaly as a % of the entire northern hemisphere. It's not actually the "% Anomaly." So an anomaly of 2-3% in summer is exactly the same as an anomaly of 2-3% in winter. The top half of the FSU chart shows this quite well.

 

For example, in late September 2012 the top chart shows that the % of the NH with snow was only 3%, while the normal was 4%. If the second chart were actually showing the "% Anomaly" or the "% of Normal" it would be about 25% below average. Instead, it reads 1% (of the entire NH) below average. Or an absolute area of 2.55 million sq km.

 

 

The largest absolute anomalies occurred in June this year with an anomaly of -4.7 million sq km. The largest positive anomaly was a mere 2 million sq km in January. This is on a 1971-2000 baseline. On the 1995-2009 FSU baseline it would probably be more like -2.7 and +4 respectively.

 

Yes the graph is not very clearly labeled, but honestly I'm surprised both of you would jump to this improbable assumption without some red flags going up.

[tacoman25]

This is false, tacoman and Jonger.

 

The "Anomalies %" is actually referring to the anomaly as a % of the entire northern hemisphere. It's not actually the "% Anomaly." So an anomaly of 2-3% in summer is exactly the same as an anomaly of 2-3% in winter. The top half of this chart shows this quite well.

 

For example, in late September 2012 the top chart shows that the % of the NH with snow was only 3%, while the normal was 4%. If the second chart were actually showing the "% Anomaly" or the "% of Normal" it would be about 25% below average. Instead, it reads 1% (of the entire NH) below average. Or an absolute area of 2.55 million sq km.

 

 

The largest absolute anomalies occurred in June this year with an anomaly of -4.7 million sq km. The largest positive anomaly was a mere 2 million sq km in January. This is on a 1971-2000 baseline. On the 1995-2009 FSU baseline it would probably be more like -2 and +4.7 respectively.

 

My point stands: winter anomalies are more significant than summer because you are talking about much larger absolute numbers for winter snow cover than summer snow cover.

[Jonger]

This is false, tacoman and Jonger.

 

The "Anomalies %" is actually referring to the anomaly as a % of the entire northern hemisphere. It's not actually the "% Anomaly." So an anomaly of 2-3% in summer is exactly the same as an anomaly of 2-3% in winter. The top half of this chart shows this quite well.

 

For example, in late September 2012 the top chart shows that the % of the NH with snow was only 3%, while the normal was 4%. If the second chart were actually showing the "% Anomaly" or the "% of Normal" it would be about 25% below average. Instead, it reads 1% (of the entire NH) below average. Or an absolute area of 2.55 million sq km.

 

 

The largest absolute anomalies occurred in June this year with an anomaly of -4.7 million sq km. The largest positive anomaly was a mere 2 million sq km in January. This is on a 1971-2000 baseline. On the 1995-2009 FSU baseline it would probably be more like -2 and +4.7 respectively.

 

My point stands: winter anomalies are more significant than summer because you are talking about much larger absolute numbers for winter snow cover than summer snow cover.

Using his numbers would show a bigger summer anomaly.

Summer snowcover anomalies have been suspicious to anyone with a set of eyes. The negative anomaly began like a light switched was flipped in 1980. We know that snow cover anomalies are determined by satellite, earlier measurements were by more primitive satellites, with more modern and higher resolution satellite's, the anomaly has stuck at 1-3% consistently.

[skierinvermont]

My point stands: winter anomalies are more significant than summer because you are talking about much larger absolute numbers for winter snow cover than summer snow cover.

 

False. A -2  or +2 million sq km in summer is just as significant as a -2 or +2 millions sq km anomaly in winter. Both have a similar effect on albedo (actually the albedo effect in summer is stronger). And both tell us similar things about how the climate has changed. In fact, the anomalies in summer tell us more because there is less variability.

[Jonger]

My point stands: winter anomalies are more significant than summer because you are talking about much larger absolute numbers for winter snow cover than summer snow cover.

 

False. A -2  or +2 million sq km in summer is just as significant as a -2 or +2 millions sq km anomaly in winter. Both have a similar effect on albedo. And both tell us similar things about how the climate has changed. In fact, the anomalies in summer tell us more because there is less variability.

I'm sure sun shining on 0.5% to 1% of the earth is going to make no impact on the planets albedo. Winter positive anomalies will take the snow cover down into lower latitudes, where albedo reflection is going to make a larger impact anyhow.

[skierinvermont]

Using his numbers would show a bigger summer anomaly. Summer snowcover anomalies have been suspicious to anyone with a set of eyes. The negative anomaly began like a light switched was flipped in 1980. We know that snow cover anomalies are determined by satellite, earlier measurements were by more primitive satellites, with more modern and higher resolution satellite's, the anomaly has stuck at 1-3% consistently.

 

False. Summer snowcover anomalies have declined steadily since satellite records began in 1967. The majority of this decline has taken place after 1980, not before. This could not possibly be related to the nearly 2C of celsius warming in the arctic that has occurred since 1980, could it?

 

Also you're assumption that satellite technology 1967-1980 was not accurate enough to detect 6 million sq km of extra snow (over 80% of the size of the contiguous U.S.) is based on zero evidence, even if the decline had occurred before 1980, which it didn't.

 

 

 

From the NOAA Arctic Report Card:

 

[skierinvermont]

I'm sure sun shining on 0.5% to 1% of the earth is going to make no impact on the planets albedo. Winter positive anomalies will take the snow cover down into lower latitudes, where albedo reflection is going to make a larger impact anyhow.

 

It's amazing how consistently wrong you are.

 

First of all, the absence of snow on a mere 1% of the earth's surface surface provides .75W/m2 of forcing if the anomaly is year round and receiving 150/m2 of solar radiation.*  In other words, a significant forcing. Fortunately, I don't believe the global snow anomaly averages 1% of the earth on an annual basis. 

 

Second of all, summer anomalies are far more significant than winter anomalies at affecting albedo. In June (the month of greatest decline), the arctic receives about 500W/m2 of solar radiation. In December, the mid-latitudes (where the anomalies are occurring) receive about 100W/m2 of solar radiation. In other words, the effect of a 1 million sq km anomaly in snow in June is about 5X that of one in December. 

 

 

*Calculation: 150W/m2 * (1%) = 1.5W/m2 * (change in albedo of .5) = .75W/m2

[skierinvermont]

Also the sole purpose of my post was to show that your reading of the chart was incorrect. Instead of recognizing this, your reaction was to switch topics with incorrect and conspiratorial assertions about the accuracy of the data.

[The_Global_Warmer]

Using his numbers would show a bigger summer anomaly. Summer snowcover anomalies have been suspicious to anyone with a set of eyes. The negative anomaly began like a light switched was flipped in 1980. We know that snow cover anomalies are determined by satellite, earlier measurements were by more primitive satellites, with more modern and higher resolution satellite's, the anomaly has stuck at 1-3% consistently.

 

 

This might be you're worst post to date.  Maybe I was wrong.  I don't think you could make this up.  Instead of taking 15 seconds to find out how they derive the data you make up baseless lies.  This in my opinion is a banable offense.  You shouldn't be allowed to post here anymore. 

 

 

From 1967-1972 the resolution used was 4KM.  After 1972 the resolution was 1KM.  We have no reliable Sea ice tracking under 6.25KM resolution, but have had snow cover tracking resolution at 1KM since 1972.

 

 

Data History

In 1966, NOAA began to map the snow and ice areas in the Northern Hemisphere on a weekly basis. That effort continues today, and remains the only such hemispheric product. NOAA maps are based on a visual interpretation of photographic copies of shortwave imagery by trained meteorologists. Up to 1972, the subpoint resolution of the meteorological satellites commonly used was around 4 km. Beginning in October 1972, the Very High Resolution Radiometer (VHRR) provided imagery with a spatial resolution of 1.0 km, which in November 1978, with the launching of the Advanced VHRR (AVHRR), was reduced slightly to 1.1 km. Maps show boundaries on the last day that the surface in a given region is seen. Since May 1982, dates when a region was last observed have been placed on the maps. An examination of these dates shows the maps to be most representative of the fifth day of the week.

It is recognized that in early years the snow extent was underestimated on the NOAA maps, especially during Fall. Mapping improved considerably in 1972 with the deployment of the VHRR sensor, and since then mapping accuracy is such that this product is considered suitable for continental-scale climate studies.

 

 

 

 

Secondly they use 89KM2 grid resolution for the snow cover product and it requires at least 50% of it to be covered to be considered snow covered, otherwise it's considered snow free.  The large grid res is used to eliminate snow edge error by giving such a large range above the actual scanning resolution. 

 

The 89KM2 grid res is 3X larger than any SIE product back to 1972.  It's 9x larger than Jaxa currently is. 

 

In case you don't know because at this point the assumption should be made you don't.  If the grid res was lower like 25km or 10km.  The snow cover extent would drop not go up. 

 

 

The NOAA maps are digitized on a weekly basis using the National Meteorological Center Limited-Area Fine Mesh grid. This is an 89 x 89 cell Northern Hemisphere grid, with cell resolution ranging from 16,000 sq. km to 42,000 sq. km. If a cell is interpreted to be at least fifty percent snow covered it is considered to be completely covered, otherwise it is considered to be snowfree.

 

 

 

Lastly:

 

More than 40 years ago they ensured high accuracy with daily reports from thousands of stations. 

 

 

 

Early NOAA Snow Cover Charts (1966-1971)

Snow cover between 1966 and 1971 was reanalyzed here at the Rutgers University Climate Lab using daily gridded composites of visible imagery for the eastern and western hemispheres of the Northern Hemisphere. Surface resolution of the imagery is approximately 25 km. The imagery was supplemented with daily reports of snow depth at several thousand stations in the U.S., Canada, China and the former Soviet Union, gridded to 1° x 1° grid cells using all reports from within a given cell. Daily surface weather charts also provided information on cloud cover, precipitation and temperature. Infrared imagery and the above ancillary information were employed in many areas to confirm interpretations made from visible data. The weekly maps were digitized to the National Meteorological Center Limited-Area Fine Mesh grid. This is an 89 x 89 cell Cartesian grid laid over a polar stereographic projection of the Northern Hemisphere. Cell resolution ranges from 16,000 to 42,000 square kilometers (this product has also been regridded to the equal area EASE-grid for November 1966 to June 2007 and is distributed by the National Snow and Ice Data Center). Each grid cell in the digitized product has a binary value. Cells with at least 50% of their surface covered with snow were considered snow covered. All other cells were considered snow free.

 

[Jonger]

 

As we know, this means all earlier measurements were retroactively tweaked upward.

 

Let me know if you can find the revision history on this, it might prove to me how wrong I might be in questioning the NOAA in this case.

 

 

[Jonger]

This is false, tacoman and Jonger.

The "Anomalies %" is actually referring to the anomaly as a % of the entire northern hemisphere. It's not actually the "% Anomaly." So an anomaly of 2-3% in summer is exactly the same as an anomaly of 2-3% in winter. The top half of the FSU chart shows this quite well.

For example, in late September 2012 the top chart shows that the % of the NH with snow was only 3%, while the normal was 4%. If the second chart were actually showing the "% Anomaly" or the "% of Normal" it would be about 25% below average. Instead, it reads 1% (of the entire NH) below average. Or an absolute area of 2.55 million sq km.

The largest absolute anomalies occurred in June this year with an anomaly of -4.7 million sq km. The largest positive anomaly was a mere 2 million sq km in January. This is on a 1971-2000 baseline. On the 1995-2009 FSU baseline it would probably be more like -2.7 and +4 respectively.

Yes the graph is not very clearly labeled, but honestly I'm surprised both of you would jump to this improbable assumption without some red flags going up.

Interesting.... that N hemisphere anomaly chart shows the positive anomaly being much higher than the negative anomaly for the year, where did you get these figures from?

[The_Global_Warmer]

You didn't question NOAA.

 

You accused Rutgers snow lab of manipulating data.  And completely made up assumptions out of thin air.  This is called lying.

 

 

You do this a lot.  It makes me wonder how far off from reality you must be..  Which means you have some issue with being way overly paranoid.

 

Or you're just playing people and intentionally lying.

[Jonger]

You didn't question NOAA.

 

You accused Rutgers snow lab of manipulating data.  And completely made up assumptions out of thin air.  This is called lying.

 

 

You do this a lot.  It makes me wonder how far off from reality you must be..  Which means you have some issue with being way overly paranoid.

 

Or you're just playing people and intentionally lying.

You need to chill out on the accusations, there is a big line you are crossing with being that personal.

[The_Global_Warmer]

You need to no break out the dictionary and read the word integrity over and over and over until it sinks in. 

[Geos]

Newest 1-year Northern Hemisphere snow chart.

 

[tacoman25]

False. A -2  or +2 million sq km in summer is just as significant as a -2 or +2 millions sq km anomaly in winter. Both have a similar effect on albedo (actually the albedo effect in summer is stronger). And both tell us similar things about how the climate has changed. In fact, the anomalies in summer tell us more because there is less variability.

 

Actually, as far as temperatures go, snow cover in winter has a more significant effect than the small amount of snow cover in summer.

 

The fact that we are building up a lot of early snowcover already (and the anomaly will likely explode upwards over the next 7-10 days as much of northern Russia will get snow) bodes well for cold air masses this coming winter.

[tacoman25]

Interesting.... that N hemisphere anomaly chart shows the positive anomaly being much higher than the negative anomaly for the year, where did you get these figures from?

 

He changed the baseline to 1971-00.

 

Going by the more recent baseline that chart is based on, yes, the positive anomalies were more significant.

[WidreMann]

Actually, as far as temperatures go, snow cover in winter has a more significant effect than the small amount of snow cover in summer.

 

The fact that we are building up a lot of early snowcover already (and the anomaly will likely explode upwards over the next 7-10 days as much of northern Russia will get snow) bodes well for cold air masses this coming winter.

Not according to Mallow: http://www.americanwx.com/bb/index.php/topic/41113-and-we-begin/?p=2418495

[skierinvermont]

Actually, as far as temperatures go, snow cover in winter has a more significant effect than the small amount of snow cover in summer.

 

The fact that we are building up a lot of early snowcover already (and the anomaly will likely explode upwards over the next 7-10 days as much of northern Russia will get snow) bodes well for cold air masses this coming winter.

 

False. Snowcover in summer has a far more significant impact on both regional (the region in which the snow anomaly is occurring) and global temperatures. 

 

A given snow anomaly in summer usually will receive 400 or 500W/m2 of solar radiation per day. The same areal anomaly in winter would likely receive only 100 or 200W/m2 of solar radiation per day, depending on exactly where it was located. Thus the effect on both regional and global temperatures in the latter case is smaller. 

 

The anomalies that occur in both summer and winter are usually of similar areal coverage. The large areas of the arctic that have seen snowcover anomalies up to 5 million sq km in recent June's have seen huge temperature anomalies over 10C.

[tacoman25]

False. Snowcover in summer has a far more significant impact on both regional (the region in which the snow anomaly is occurring) and global temperatures. 

 

A given snow anomaly in summer usually will receive 400 or 500W/m2 of solar radiation per day. The same areal anomaly in winter would likely receive only 100 or 200W/m2 of solar radiation per day, depending on exactly where it was located. Thus the effect on both regional and global temperatures in the latter case is smaller. 

 

The anomalies that occur in both summer and winter are usually of similar areal coverage. The large areas of the arctic that have seen snowcover anomalies up to 5 million sq km in recent June's have seen huge temperature anomalies over 10C.

 

It's not as simple as solar radiation albedo. You realize that snowcover extent effects air temperatures at night too, right? Snow cover extends much further south in the winter, and the greater the snow cover, the easier it is to generate very cold air masses further south.

[tacoman25]

Not according to Mallow: http://www.americanwx.com/bb/index.php/topic/41113-and-we-begin/?p=2418495

 

I believe that correlation is mainly linked to a big increase during October. Which I suppose could be more difficult if you start off October with a big +anomaly....but looking at previous years that got off to a fast start early in the fall, it seems to be a good sign.

[tacoman25]

Just to give an idea of how much more of the NH is covered by snow during winter.