The comparison of snowiness changes over the mountains and over the plains according Caucasus and Ea

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The comparison of snowiness changes over the
mountains and over the plainsaccording Caucasus
and East European plain example

• Natalia Volodicheva, Lev Kitaev,
• Alexander Krenke and Alexander Oleinikov

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The goal

• To compare the snowiness changes in the
  mountains and over the plain in relation to the
  general circulation patterns.

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Data

• 636 plain stations including 290 to the south
  from 50? N
• of East European plain and 60 over the
  Northcaucasien
• piedmont and plains.
• 27 stations in the Great Caucasus.
• Inventory of atmospheric circulation patterns
• according to B.Dzerdzeevsky
• western Lows 1a5a5b 7bw 8bw 11a 11b
  11c 12d
• southern Lows 1b 5d 7aw 8a 9b12bw 12cw
  
• arctic intrusions 4a 8bw
• stationary Highs 5b 13w.

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Snowiness

• Snowiness is the average snow thickness for the
  winter period in percent
• less than 30 - minimal snowiness
• 30-100 - mean snowiness
• more than 100 - anomalous snowiness
• Snowiness and maximum snow water storage
• couincide in more than 80 cases. They differ in
  case
• of very early or late accumulation of snow.

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Location of stations with snow depth observations
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Spatial changes

• Snowiness in the mountains is 6 times and
  interannual amplitude is seven times more in the
  mountains. The increase to the NE over the plain
  and to the SW and with the altitude in the
  mountains.

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Spatial changes

• The coefficient of variation for
• the averaged values for all the
• plain and for all mountain
• stations is of the order 30.
• For the single Caucasian
• stations with the high
• snowiness the coefficient of
• variation is about 30-45, the
• maximum deviation is about
• 90. For the single stations
• with the low snowiness the
• coefficient of variation is about
• 90-100 with 3-5 times
• maximum deviation.

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Interannual variability

• Cv is close to 0,3 everywhere for averaged
  figures. For the single low snow stations it
  grows up to 1,0.
• Trend is positive last decades over the plain,
  only oscillation in the Caucasus.

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Interannual variability

• The anomalies signs are
• opposite between the plain
• and mountains in half of the
• cases.
• Sometimes (1986/1987)
• the same very strong
• anomalies. The anomalies
• are similar over the whole
• plain, including
• Northcaucasian piedmont.
• Though they differ from the
• Great Caucasus.

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Circulation factors of anomalies

• Sinchronous positive anomalies over the plains
  and in the mountains are related to the strong
  southern intrusions. High snow years only over
  the plain arctic intrusions, only in the
  Caucasus stationary High over the plain and
  deviation of western Lows to the south.

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CONCLUSIONS

• 1.   SNOWINESS CHANGES ARE SIMILAR
• OVER THE WHOLE RUSSIAN PLAIN,
• INCLUDING NORTHCAUCASIAN
• PIEDMONT. HOWEVER THEY
• DIFFER FROM THE MOUNTAINS
• THE ANOMALIES SIGNS ARE
• OPPOSITE IN THE HALF OF THE
• CASES.

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CONCLUSIONS

• 2. DURING THE LAST DECADES THERE IS
• THE POSITIVE TREND OF THE
• SNOWINESS OVER THE PLAIN. IN THE
• MOUNTAINES ONLY INTENSIVE
• OSCILLATION ARE MARKED.

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CONCLUSIONS

• 3. THE BIG SNOWINESS OVER THE
• PLAIN IS DETERMINDED BY THE
• ARCTIC INTRUSIONS, THE WESTERN
• OR VERY STRONG SOUTHERN LOWS.

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CONCLUSIONS

• 4.  THE BIG SNOWINESS IN THE
• GREAT CAUCASUS IS DETERMINDED
• BY THE SOUTHERN LOWS OR BY
• THE WESTERN ONES, WHOSE
• TRACKS ARE DEVIATED TO THE
• SOUTH BY THE GREAT HIGHS OVER
• THE EAST EUROPEAN PLAIN.

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