Climate trends from stations

Can we see an increase in air temperature from the Swiss climate network Swiss NBCN? If so, is it significant? Are precipitation sums increasing or decreasing? Are these trends the same for all stations? Are there differences concerning the seasons? The following graphics give answer to  these questions.

Annual and seasonal homogeneous climate trends of mean air temperature from 29 stations of the Swiss NBCN and of precipitations sums from 46 additional stations (NBCN-P) are illustrated for 14 different periods.

Legend: The area of the circles exemplifies the extent of the change per decade (°C for temperature an % for precipitation).

• Temperature: red = positiv, blue = negativ
• Precipitation: green = positiv, orange = negativ

Significant trends on the 95%-niveau are marked by filled circles. The calculation of the trends uses "least-squares" for temperature and the Theil-Sen method for precipitation (Sen, 1968; Theil, 1950). The level of significance was estimated non-parametric (Mann, 1945; Kendall, 1975).

• Kendall M.G., 1975: Rank Correlation Methods, Charles Griffin, London
• Mann H.B., 1945: Nonparametric tests against trend. Econometrika 13:245-259
• Sen P.K., 1968: Estimates of the regression coefficient based on Kendall's tau. Journal of the American Statistical Association, 63, 1379-1389.
• Theil H., 1950: A rank-invariant method of linear and polynomial regression analysis. Netherlands Akad. Wetensch. Proc., 53, pages: 386-392 (part I), 521-525 (part II), 1397-1412 (part III).