Pavel TOROPOV, Vladimir MIKHALENKO, Stanislav KUTUZOV Physical mechanisms of the intensive melting of glaciers of the North Caucasus in the last 20 years Pavel TOROPOV, Vladimir MIKHALENKO, Stanislav KUTUZOV Fac. of Geography Institute of Geography

How the climate changed in the mountains last 20 years? Tibetan plateau 1961-1990 & 1991-2010 Himalayas: ΔT = 0.2 – 0.3 C Andes: ΔT = 0.3 – 0.4 C Alps: Pepin N., Bradley R. S., Diaz H. F., et al. Elevation-dependent warming in mountain regions of the world. // Nature Climate Change. Vol. 5. May 2015. pp. 424-430.

As a result of warming in the mountains rapid melting of glaciers across the world

Degradation of the glaciers of the Central Caucasus: Djankuat glacier (results from V. Popovnin) Garabashi glacier Cumulative mean annual mass balance Cumulative mean annual mass balance accumulation accumulation Ablation

How to estimate the climate change in the Caucasus? Using: WMO’s meteorological station Measurements of scientific expeditions can not be used because: a very small number of mountains stations statistically heterogeneous series of observations can not be used because: a very short time-serials of measurements

The only way - is to use the reanalysis’s data…For example, NCEP/NCAR Global model of atmospheric circulation Global observation data We used NCEP/NCAR reanalysis’s data for summer season since 1948 to 2011 years. Spatial resolution of data: 2 x 2 degrees Temporary resolution – 1 day Using data: air temperature, wind and humidity on the geopotential surfaces 500, 700, 850 hPa (in free atmosphere) reanalysis data were compared with the results of meteorological observations in the Elbrus expedition Gridded meteo-data

Example of radiation budjets’s data, they were received in the Elbrus expedition 2013 (подписи осей, и т.д.)

How to estimate the reanalysis ‘ s data? Western plateau, 5100 m Eastern top, 5635 m m.Elbrus Terskol, 2200 m Garabashi, 3850 m

Surface temperature according to our observations (red line) and reanalysis’s data (blue line) 01.VII 10.VII 20.VII 30.VII 10.VIII 20.VIII 01.VII 10.VII 20.VII 30.VII 10.VIII 20.VIII 01.VII 10.VII 20.VII 30.VII 10.VIII 20.VIII 01.VII 10.VII 20.VII 30.VII 10.VIII 20.VIII T, °C Eastern top, 5635 m CORREL = 0.86 Garabashi, 3850 m CORREL=0.81 Terskol, 2250 m CORREL = 0.79 Western plateau, 5100 m CORREL = 0.84

Wind speed according to our observations (green line) and reanalysis’s data (black line) on station Garabashi Garabashi, 3850 m CORREL=0.71

Temperature anomaly, renalisys data Wind speed anomaly, renalisys data The air temperature and wind speed (Garabashi) during the season of ablation for the period 1948-2010, reconstructed according to the reanalysis NCEP/NCAR. Temperature anomaly, renalisys data Gaussian distribution Temperature, °C ΔV, м/с Wind speed anomaly, renalisys data Weibull distribution Speed of wind, m/s Скорость ветра, м/с

Frequency of wind direction according to the reanalysis data Western plateau (5150 m) Garabashi (3850 m)

The summer temperature changed not fast…But why Caucasian’s glaciers melts so fast?

The structure of the heat balance of the «warm» glacier В Pliq H LE the contribution of the radiation budget in the melting: 85-90%

Comparison of the components of the heat balance of glaciers Dzhankuat (left) and Tyndall (right)

Components of the radiation budget of the Central Caucasus from reanalysis data MJ/m2 Short-wave budget Long-wave budget Total radiation budget Cumulative mean annual mass balance

Spatial distribution of linear trends of temperature 1984 - 2015 WINTER, C/10yr SPRING, C/10yr SUMMER, C/10yr AUTUMN, C/10yr

Spatial distribution of summer linear trends for 1984 - 2015 CAPE, Dj/kg MOISTURE IN THE COLUMN, kg/m2 TREND OF CAPE, Dj/kg/10yr TREND OF MOISTURE, kg/m2/10yr

Last 35 years in the summer is dominated by anticyclonic circulation LINEAR TREND OF DIVERGENCE LINEAR TREND OF VERTICAL SPEAD MERIDIONAL SECTION OF TREND OF VERTICAL SPEAD

Conclusions Increasing summer temperatures in the Central Caucasus in the last 20 years is statistically insignificant. Intensive ablation in the last 15-20 years, with an increase of radiation associated budget of 3-5% over the period 1961-1990 Similar results were obtained in the Alps, in particular in [Philipona, 2012]. In these studies analyzed the observational data - is very important. The reason for the increase in the radiation budget of the Central Caucasus - the growth of total radiation budget – firstly, long-wawe component. It may be associated with an increase atmospheric humidity, and increase in the frequency of anticyclones