HOMOGENEITY OF THE ECA TEMPERATURE DATA Janet Wijngaard KNMI, The Netherlands PISA, 16-20 October

High quality data Climate variability and extremes analysis What about the quality of the data? Annual DTR series: - artificial changes opposite effect - natural changes same effect

HomogeneityTests No reference stations used: Four tests applied: stations are too diverse and coarse network Four tests applied: Standard Normal Homogeneity Test (Alexandersson) Buishand Range test, based on cumulative sums Pettitt test, non-parametric (Sneyers) Von Neumann ratio

CONCLUSIONS Test results: first indication for homogeneity Meta data should be used to verify results Quality/Homogeneity check important take full advantage of the ECA data set ECD

Testing Variables Diurnal Temperature Range annual mean annual standard deviation of day-to-day changes Annual number of wet days (>1 mm)