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. 2015;33:42–53. doi: 10.1016/j.dendro.2014.11.004

Table 3.

Mean monthly temperature, precipitation and radiation averaged for light ring years and remaining normal years. Student-t tests verify significance level of differences between those two groups of years. For calculations monthly averaged data for temperature (1780–2008 – 6 light ring years) and for solar radiation (1884–2008 – 4 light ring years), as well as monthly sums of precipitation (1800–2008 – 6 light ring years) were used.

Months Mean temperatures and in parentheses standard deviations
Verification of the difference between light ring years and remaining years
Mean precipitations and in parentheses standard deviations
Verification of the difference between light ring years and remaining years
Mean radiations and in parentheses standard deviations
Verification of the difference between light ring years and remaining years
Remaining years Light ring years Student t test Significance levels Remaining years Light ring years Student t test Significance levels Remaining years Light ring years Student t test Significance levels
January −5.2 (2.4) −6.4 (1.9) 1.514 P < 0.10 10.6 (6.2) 13.3 (8.0) −0.816 Not significant 4.7 (1.9) 4.7 (1.3) −0.001 Not significant
February −4.3 (2.4) −5.2 (3.0) 0.670 Not significant 10.5 (6.3) 9.1 (4.9) 0.709 Not significant 8.9 (3.3) 6.9 (1.3) 2.518 P < 0.01
March −1.6 (2.1) −2.1 (1.6) 0.686 Not significant 11.8 (6.3) 9.1 (5.2) 1.237 P < 0.10 13.5 (3.6) 15.1 (3.7) −0.751 Not significant
April 2.3 (1.7) 1.6 (1.5) 1.154 Not significant 12.0 (5.3) 11.7 (2.5) 0.260 Not significant 16.3 (4.2) 15.0 (7.4) 0.297 Not significant
May 7.3 (1.8) 6.8 (1.4) 0.815 Not significant 13.1 (4.6) 14.7 (4.6) −0.834 Not significant 22.1 (4.3) 23.2 (4.2) −0.437 Not significant
June 10.3 (1.5) 9.8 (0.9) 1.511 P < 0.10 20.0 (5.5) 22.8 (7.1) −0.938 Not significant 22.4 (4.3) 24.5 (4.1) −0.865 Not significant
July 12.2 (1.4) 11.9 (0.8) 0.995 Not significant 23.2 (6.7) 22.9 (3.2) 0.217 Not significant 23.0 (4.2) 22.9 (2.4) 0.012 Not significant
August 12.0 (1.4) 9.9 (0.9) 5.650 P < 0.0005 21.1 (6.2) 24.1 (5.4) −1.354 Not significant 23.4 (4.2) 17.3 (0.6) 11.533 P < 0.0005
September 9.1 (1.5) 7.5 (2.4) 1.655 P < 0.05 15.3 (6.6) 19.6 (7.1) −1.472 Not significant 17.7 (4.0) 11.7 (8.2) 1.267 Not significant
October 4.9 (1.7) 3.9 (1.6) 1.524 P < 0.10 11.2 (5.9) 9.2 (5.6) 0.829 Not significant 11.4 (3.7) 9.9 (2.9) 0.881 Not significant