An Examination of External Influences in Utahs Historical Snow Data

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An Examination of External Influences in Utahs
Historical Snow Data Because things change and
so does perspective!
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What makes a Scientist MAD? Finding out after
results and conclusions that the data used
have SYSTEMATIC BIAS AND ERRORS
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Lets start with physical change
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1. Statistically comparing 90-05 with 37-50 shows
less snow and 2. the decline occurred prior to
1990! From 90 on, little change.
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Burts Miller Ranch - 1936
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Note the open meadow and the height of the trees
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Burts Miller Ranch 2005 note a subtle change
not vegetation topography!
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Impact from sub-surface irrigation
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Influence of a spring/sub surface water on
snowpack Franklin Basin
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Sample points 4 and 5 get statistically less snow
now and have switched places with 5 getting much
less
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Yankee Meadows Snow course with the stream
re-routed through the course
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Beaver Dams hit by mud flow moved to meadow
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Harris Flat wind patterns thru the trees.
Pillow moved.
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Sensor Changes Steel to Hypalon average 13
reduction of SWE
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All of SNOTEL had Steel on original installation
some areas went carte blanc to hypalon, others
as steel pillows fail. There is a systematic SWE
decrease in the SNOTEL data due to sensor change
ranging from 0 to 25, avg 13. Changes are
more predominant at lower elevations.
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Soil plug from snow sample under 121 inches of
snow at Snowbird, Utah, May 11, 2006. There is
sufficient light to generate photosysnthesis.
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Transducer errors 0.1 to 5.0 inches of SWE
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Lets move to VEGETATION CHANGE
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No statistical difference between 90-05 and 39-48
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Garden City Summit
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Garden City Summit
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Garden City Summit
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Garden City looking north - affects of aging
conifers and new growth on accumulation and
ablation - lowering the average SWE over time.
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Impact of long wave radiation on snow this hole
was caused by a 1.48 inch soil plug from the snow
course total time was about 1 month.
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Redden Mine influenced by Vegetation, Pollution
and Cloud Seeding
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Snow Course plotted against the SNOTEL site
clearly observed is a decrease in SWE
accumulation on the pillow beginning in the early
90s - due to ???
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Here is context we got new neighbors, they cut
trees, cleared brush and changed the snow
accumulation patterns.
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Buckboard Flat influenced by Vegetation change.
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Timberline
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Fish Lake no substantial Vegetation Change
Cloud Seeding?
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GBRC Meadows observed data shown cloud
seeding? Using adjusted data, statistically less
snow.
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Gooseberry cloud seeding?
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Huntington observed data. Using adjusted data
has statistically less snow not due to
vegetation or other change.
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And we thought we had problems with snowmobiles.
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Brian Head snow course pre-beetle kill and logging
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Brianhead post beetle kill and logging
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Lily Lake
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Weather Modification impacts on snow measurement
sites in Utah 50 and 100 mile radius from
generator sites. A general 14 increase for the
specific years of operation in any given area.
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Mill D South Pollution impacts? -15 to -25
Note the hillside in the background
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Snow Course no change. Hillside a complete
forest. Predicted in the 70s, conversion from
aspen to conifer could impact watershed runoff as
much as 7 inches or more. 4 to 10 million acres
of aspen has been replaced by conifer. Impacting
streamflow?
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Timing errors, SNOTEL vs Snow Course, about 0.5
inches or 1.7
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The total percent change to the 1971-2000 average
for each site in Utah to NORMALIZE the data.
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Temperature Data Initial system could not
transmit temperature data Added later Sometimes
on the shelter Sometimes on a tower Various
aspirators Various thermistors Mid 90s
standardization to tower installation, 7, 17 or
27 feet, white aspirator and extended range
thermistor.
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Tower mounted thermistor with wind direction
funnel aspirator mounted at 20 feet, 24 inches
from tower.
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Mounted near top and offset on shelter, silver
aspirator
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Current installation 5 to 6 feet from tower,
white aspirator, extended range thermistor
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• Current temperature data collection status
• All sensors currently are mounted on
  meteorological tower at 7, 17 or 27 feet and
  about 5 feet from the tower.
• All sensors are currently extended range
  thermistors.
• About 50 have white aspirators, the rest have
  the older aluminum aspirators. We still have a
  ways to go to completely standardize temperature
  data collection.
• Much of the temperature data pre 2000 could have
  significant bias due to mounting location some
  would be reasonably good if mounted on the tower.
• Meteorological towers were installed starting in
  the mid 1990s standardizing all data
  collection at the snow pillow.
• SUMMARY I WOULDNT GIVE A TINKERS DAMN FOR MOST
  OF THE DATA SET AT THIS POINT!

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• General Findings Major Impacts
• Physical changes 21 sites, 16 of total
• Vegetation Change 11 major, 32 Moderate and 91
  had little to no change. 32 of sites have change
  that impacts accumulation. (-5
  to -30)
• Pollution 32 sites (24 of total) potentially
  impacted by pollution (-15 to -25)
• Weather Modification All sites but Lasal
  Mountain snow course and Snotel, Camp Jackson and
  Buckboard Flat. (5 to 20)

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64 sites in Utah 48 of the total have had
either significant vegetative, physical or
pollution impacts that could negatively change
snow accumulation / ablation patterns.
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Statistical comparison of observed April 1 SWE
data
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Statistical comparison of adjusted April SWE data
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• General Observations
• No real pattern of statistically significant
  decreased SWE in the long term snow courses using
  these statistical methods.
• A presumed signature of Global Warming
  (decreased snowpack at lower elevations and
  southern latitudes) is not statistically
  detectable from other influences in Utahs
  snowpack data at this time using these
  techniques. Other researchers have found
  decreased SWE.

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3. Attributing a change (decrease/increase) in
snowpack accumulation/ablation characteristics to
a single specific cause is difficult to
statistically prove given the multiplicity of
other influences impacting snowpack in Utah.
4. This is precisely why we use 30 year averages
to reflect CURRENT conditions.
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Our Recommendation for Long Term Snow Study in
Utah