Transcript HOMOGENEITY OF THE ECA TEMPERATURE DATA

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:
– 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)