Long-term change, interannual and intra-seasonal variability in climate and glacier mass balance in the central Greater Caucasus, Russia

Abstract

Long-term trends, interannual and intra-seasonal variability in the mass-balance record from Djankuat glacier, central Greater Caucasus, Russia, are related to local climate change, synoptic and large-scale anomalies in atmospheric circulation. A clear warming signal emerged in the central Greater Caucasus in the early 1990s, leading to a strong increase in ablation. In the absence of a compensating change in winter accumulation, the net mass balance of Djankuat has declined. The highest value of seasonal ablation on record was registered in the summer of 2000. At the beginning of the 21st century these trends reversed. Ablation was below average even in the summer of 2003, which was unusually warm in western Europe. Precipitation and winter accumulation were high, allowing for a partial recovery of net mass balance. The interannual variability in the components of mass balance is weakly related to the North Atlantic Oscillation (NAO) and the Scandinavian teleconnection patterns, but there is a clear link with the large-scale circulation anomalies represented by the Rossby pattern. Five synoptic categories have been identified for the ablation season of 2005, revealing a strong separation between components of radiation budget, air temperature and daily melt. Air temperature is the main control over melt. The highest values of daily ablation are related to the strongly positive NAO which forces high net radiation, and to the warm and moist advection from the Black Sea.

A sensitivity study for water availability in the Northern Caucasus based on climate projections

“…Atmospheric circulation is dominated by westerly flow in the upper atmosphere above the 500 hPa level (Lydolph, 1977). In summer, extensions of the Azores high prevail (Shahgedanova et al, 2007). Superimposed on the general circulation is the influence of the Black Sea (exerting greater influence due to its position to the southwest) and the Caspian Sea, as well as more complex orographic effects resulting in complex spatial precipitation patterns and extremely strong precipitation gradients (Volodicheva, 2002;Shahgedanova et al, 2007).…”

“…The inter-seasonal variability in precipitation intensity in the catchment was also shown to be strong especially in the warm season. In the summer of 2005, the daily precipitation amounts ranged on average from 2 mm day − 1 on the days when extensions of the Azores high dominated to 9 mm day − 1 when the advection from the Black Sea prevailed (Shahgedanova et al, 2007).…”

“…Regional meteorological indices were selected on the basis of prior knowledge of physical links between regional indices and local processes (e.g. Shahgedanova et al, 2007) and using partial correlation coefficients between the indices and the target variables (Table 1). Multiple regression models were calibrated for both temperature and precipitation using the selected predictor variables.…”

“…The water yield from the Caucasus Mountains has profound impact on the Caspian Sea, where the current rise of the water level threatens coastline infrastructure (Shayegan and Badakhshan, 1996;Kislov and Toropov, 2008). The previous studies have shown that summer temperatures have been increasing in the glaciated regions of the Caucasus since the late 1960s at a rate of 0.05°C a − 1 (Shahgedanova et al, 2005(Shahgedanova et al, , 2007(Shahgedanova et al, , 2009 and the extent of glaciated area has declined by 10% between 1980 and 2000 in response to the observed warming (Stokes et al, 2006). Results of regional climate modelling have shown that the summer air temperature will increase in the glaciated regions by 4-7°C and 3-5°C in 2071-2100 and the A2 and B2 emission scenarios (Nakicenovic et al, 2000) in comparison with and deglaciation of the region will continue (Shahgedanova et al, 2009).…”

Climate Change Impacts and Adaptations in the Countries of the Former Soviet Union

“…Warmer summer temperature (increased by 0.05 • C per annum since the late 1960s) has resulted in an intensified glacier melt with the pick in the 1990s, which has not been offset by the cold season precipitation increase. This trend has been especially strong in the last two decades possibly as a response to the weakening Arctic High (Georgia's Initial National Communication under the UNFCC 1999) and strongly positive phase of the North Atlantic Oscillation (NAO; Shahgedanova et al 2007Shahgedanova et al , 2009b. Even though it can be fairly said that the climate in the region becomes drier, there is a lot of heterogeneity.…”