Kitaev3 Slides

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

The comparison of snowiness changes over the mountains and over the plains according Caucasus and East European plain example Natalia Volodicheva, Lev Kitaev, Alexander Krenke and Alexander Oleinikov

The goal : 

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

Data : 

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 – 1a;5a;5b; 7bw; 8bw; 11a; 11b; 11c; 12d; southern Lows – 1b; 5d; 7aw; 8a; 9b;12bw; 12cw; arctic intrusions – 4a; 8bw; stationary Highs – 5b; 13w.

Snowiness: 

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.

Location of stations with snow depth observations: 

Location of stations with snow depth observations

Spatial changes: 

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.

Spatial changes: 

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.

Interannual variability : 

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.

Interannual variability: 

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.

Circulation factors of anomalies : 

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.

CONCLUSIONS: 

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.

CONCLUSIONS: 

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.

CONCLUSIONS: 

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

CONCLUSIONS: 

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.