Climate
An overall warming pattern is manifest in the long-term air temperature
record from Svartberget from 1980 to present, but becomes even more
visible when extending the time series back to 1891 by using the nearby
Stensele site (Fig 2) for extrapolation. Air temperature has increased
by about 3.5 ⁰C since 1891 of which approximately 2.0 ⁰C has occurred in
the last 40 years (Mann-Kendall test, p<0.001). The seasonal
air temperature for winter, spring, summer and fall have all increased
almost uniformly over the 40 years of monitoring by approximately 0.05
degrees ⁰C per year (Fig 2b, Mann-Kendall test, p<0.01 for all
seasons), which among other consequences are manifested in the 50 year
spring ice-off record for a lake just north of Krycklan (Fig 3b). Total
annual average precipitation equals 623 mm, ranging from 446 (1994) to
918 mm (1982), with no statistical trend over the last 40 years. Of the
precipitation, approximately 30% arrives as snow. The average snow
water equivalents (SWE) for the 40 years of record is 180 mm, ranging
from 64 (1996) to 321 (1988) mm. The 40-year average duration of winter
snow cover is 167 days, but this is decreasing over time. During the
first decade of measurement, the average date of initial snow cover was
in early November; since then, this onset has been delayed by
~0.5 day yr-1.(Laudon and Löfvenius,
2016). However, the melting of snow in spring has experienced no
significant trend, and on average occurs in late April. The long-term
average annual runoff at a forest dominated catchment (C7; Fig 3a) has
been 298 mm, with a minimum of 112 mm (1996) and maximum of 555 mm
(2000) (cf Teutschbein et al., 2018).