HYDROMETEOROLOGICAL FORCING OF WESTERN RUSSIAN ARCTIC COASTAL DYNAMICS: XX-CENTURY HISTORY AND CURRENT STATE

Abstract

The Arctic coasts in permafrost regions are currently quickly retreating, being extremely vulnerable to the ongoing environmental changes. While the spatial variability of their retreat rates is determined by local geomorphological and cryolithological aspects, their temporal evolution is governed mainly by hydrometeorological factors, namely, wave action coupled to thermoabrasion (thermodenudation), are active during ice- free period. We define the combined wave and thermal action as “hydrometeorological stress”, and analyze its components and evolution, confirming it by known natural and remote sensing observations of coastal retreat rates. We estimated changes in the main hydrometeorological factors in the XX and XXI centuries for several sites on the coasts of the Kara andBarentsSeasbasing on observation and ERA reanalysis data. The term of hydrometeorological forcing is intended as an increment of the hydrometeorological stress, occurring because of changes of the hydrometeorological factors. Our results show that the current thermodenudation forcing amounts 15-50% of the 1979-1988 mean level and thermoabrasion forcing is equal to 35-130%. We detected 1989 (1993) – 1997 and 2005 – 2013 as periods of extreme hydrometeorological stress, as far as both thermodenudation and thermoabrasion were in a positive phase. It was also revealed that the hydrometeorological stress of the recent 10 years was apparently unprecedentedly high at the Barents-Kara region: the previous Arctic warming of the 1930-40s caused high thermoabrasion rates due to longer ice-free period despite cold summer temperatures, while, the latest ongoing warming shows previously unseen simultaneous increase in both thermodenudation and thermoabrasion.