









Statistics for polar willow growth-ring chronology_
| Parameter | |
|---|---|
| Time period (>3series) | 1951–2011 |
| Chronology length (>3series) | 60 |
| Number of series | 21 |
| Mean series length | 38 |
| Mean growth-ring width (Standard deviation) (mm) | 0.14 (0.08) |
| Mean index (Standard deviation) | 0.96 (0.58) |
| Mean series correlation with master | 0.44 |
| Mean inter-series correlation (Rbar) | 0.32 |
| Expressed population signal (EPS) | 0.82 |
| Mean sensitivity | 0.56 |
| Autocorrelation 1storder, unfiltered / filtered | 0.27/-0.01 |
Values of trend coefficients of climate and tree-ring variables and their statistical characteristics_
| Variable | Trend coefficient | R | R2 | p< | N | Trend per decade |
|---|---|---|---|---|---|---|
| Mean growth ring width | 1.20 (± 0.50) | 0.33 | 0.11 | 0.019 | 50 | 12.0 μm |
| Maximum growth ring width | 3.50 (± 1.10) | 0.42 | 0.17 | 0.003 | 50 | 35.0 μm |
| Annual air temperature | 0.10 (± 0.02) | 0.70 | 0.49 | 0.000 | 34 | 1.1 °C |
| Annual precipitation | 4.27 (± 1.51) | 0.45 | 0.20 | 0.008 | 34 | 42.7 mm |
Climatic conditions of the negative pointer years_
| Year | The annual air temperature of the previous year | Absolute minima of air temperature | Number of days with positive mean diurnal air temperature in winter (Jan-Feb) | Totals of atmospheric precipitation in May | Percentage of relative sunshine duration in July | Sunshine duration in July | Mean thickness of snow cover in January | Mean thickness of snow cover in May | Mean thickness of snow cover in June | Number of days with snow cover in June | |
|---|---|---|---|---|---|---|---|---|---|---|---|
| (°C) | (°C) | (mm) | (%) | (hours) | (cm) | (cm) | (cm) | ||||
| Reference period means | 1978-2012 | -4.1 | -26.9 | 3.3 | 20.1 | 20.9 | 155.4 | 17.9 | 28.4 | 13.8 | 13.8 |
| Negative pointer years | 1958 | - | -24.8 | - | - | - | 104.2 | - | - | - | - |
| 1967 | - | - | - | - | - | - | - | - | - | - | |
| 1975 | - | - | - | - | - | - | - | - | - | - | |
| 1980 | -6.2 | -30.2 | 5 | 9.1 | 15.5 | 115.0 | 17 | 44 | 21 | 10 | |
| 1981 | -5.8 | -35.9 | 0 | 26.3 | 19.5 | 145.2 | 7 | 40 | 35 | 30 | |
| 1989 | -7.3 | -28.5 | 0 | 5.2 | 9.8 | 72.7 | 22 | 7 | 0 | 0 | |
| 1999 | -4.9 | -22.9 | 1 | 11.2 | 21.5 | 159.8 | 14 | 11 | 6 | 4 | |
| 2006 | -2.6 | -20.5 | 15 | 45.6 | 7.1 | 53.0 | 10 | 5 | 0 | 0 | |
| 2010 | -2.7 | -23.7 | 9 | 20.3 | 10.6 | 78.9 | 21 | 13 | 5 | 10 |