Long-term variability and trends in annual snowfall/total precipitation ratio in Finland and the role of atmospheric circulation patterns

• This study evaluated variabilities and trends in annual snowfall to total precipitation (S/P) ratio at Sodankyla, Kajaani and Kaisaniemi weather stations in northern, central and southern Finland during 1909-2008. Annual S/ P ratio was estimated using daily precipitation and temperature records as input to a calibrated and validated temperature-index snowmelt model developed to simulate snowpack accumulation and melt processes in Finland. Factors controlling variations in annual S/P ratio and their relationships with large-scale atmospheric circulation patterns (ACPs) were also studied. The results show that there were significant declines in annual S/P ratio during 1909-2008, which were principally attributable to century-long decreasing trends in annual snowfall (S) in Finland. These reductions in annual S were predominantly controlled by both annual rainfall (R) and snowfall-day temperature (ST) in the south, annual ST in the centre, and annual R in the north. However, dividing the 100-year study period into an early (1909-1958) and late (1959-2008) periods revealed non-linear trend behaviours in annual S and consequently annual S/P ratio during 1909-2008. The Arctic Oscillation, East Atlantic, East Atlantic/West Russia and Scandinavia patterns were the most influential ACPs for annual S variability.

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Miljövetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Environmental Sciences (hsv//eng)

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Meteorologi och atmosfärforskning (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Meteorology and Atmospheric Sciences (hsv//eng)

Nyckelord

Snowfall/precipitation ratio

Temperature

Trend analysis

Atmospheric circulation

Finland

snow cover

northern-hemisphere

air-temperature

decadal trends

united-states

climate

classification

oscillation

projections

streamflow

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