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Homogenization of

Sixth seminar for homogenization and quality control in climatological DB . Budapest 2008. Homogenization of. Italian precipitation series. Andrea Toreti 1,2 , Franco Desiato 1 , Guido Fioravanti 1 , Walter Perconti 1.

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Homogenization of

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  1. Sixth seminar for homogenization and quality control in climatological DB Budapest 2008 Homogenization of Italian precipitation series Andrea Toreti1,2, Franco Desiato1, Guido Fioravanti1, Walter Perconti1 1 APAT – Climate and Applied Meteorology Unit 2 University of Bern andrea.toreti@apat.it

  2. Sixth seminar for homogenization and quality control in climatological DB– Budapest 2008 59 stations – Air Force Weather Service and some Regional Environmental Agencies • Weak climatological control • Consistency control Outlier detection (using filter constructed in function of season, latitude and altitude + spatial comparison) www.scia.sinanet.apat.it Correction or elimination of wrong values Monthly Series

  3. Sixth seminar for homogenization and quality control in climatological DB– Budapest 2008 Monthly Series KZA – Kolmogorov Zurbenko Adaptive Filter1 Moving Window SNHT – Standard Normal Homogeneity Test2 MRPP – Multi Response Permutation Procedure3 1. Zurbenko et al. 1996. Detecting discontinuities in time series of upper air data: development and demonstration of an adaptive filter technique. J. of Climate 9, 3548 – 3560. 2. Alexandersson and Moberg. 1997. Homogenization of Swedish temperature data. Part I: homogeneity test for linear trends. Int. J. of Climatology 17, 25 – 34. 3. Mielke et al. 1981. Application of multi response permutation procedure for examining seasonal changes in monthly mean sea level pressure patterns. Monthly Weather Rev. 109, 120 - 126

  4. Sixth seminar for homogenization and quality control in climatological DB– Budapest 2008 KZA filter does not involve a reference series Let Xt be the ‘candidate’ … and Z is the Kolmogorov Zurbenko filter of X

  5. Sixth seminar for homogenization and quality control in climatological DB– Budapest 2008 An example of KZA filter

  6. Sixth seminar for homogenization and quality control in climatological DB– Budapest 2008 Moving Window SNHT • Reference Series: at least three stations chosen using best correlation criterion applied to first difference series. • Window length: 12 years. • Inhomogeneities identified in the first/last four years were discarded. MRPP • It is non parametric • Window length: 96 values; Centred at the inhomogeneity point • Two groups: before and after inhomogeneity • Comparison of Euclidean distances

  7. Sixth seminar for homogenization and quality control in climatological DB– Budapest 2008 MRPP a partition into g+1 disjoint subgroups: S1,…, Sg+1 where ΔIJ is the Euclidean distance between two members (I and J) of Si The Statistic

  8. Sixth seminar for homogenization and quality control in climatological DB– Budapest 2008 An example: Enna November 1964

  9. Sixth seminar for homogenization and quality control in climatological DB– Budapest 2008 Homogenized series Standardized anomaly series1. Reference period: 1971 - 2000 • Annual Series since December until November: Northern IT, Central IT and Southern IT • Seasonal Series: DJF / MAM / JJA / SON 1 Jones and Hulme. 1996. Calculating regional climatic time series for temperature and precipitation: methods and illustrations. Int. J. of Climatology 16, 361 – 377.

  10. Sixth seminar for homogenization and quality control in climatological DB– Budapest 2008 Northern Italy. Comparison

  11. Sixth seminar for homogenization and quality control in climatological DB– Budapest 2008 Northern Italy. Comparison

  12. Sixth seminar for homogenization and quality control in climatological DB– Budapest 2008 Central Italy. Comparison

  13. Sixth seminar for homogenization and quality control in climatological DB– Budapest 2008 Central Italy. Comparison

  14. Sixth seminar for homogenization and quality control in climatological DB– Budapest 2008 Southern Italy. Comparison

  15. Sixth seminar for homogenization and quality control in climatological DB– Budapest 2008 Southern Italy. Comparison

  16. Sixth seminar for homogenization and quality control in climatological DB– Budapest 2008 Annual series. Comparison

  17. Sixth seminar for homogenization and quality control in climatological DB– Budapest 2008 Annual series. Comparison

  18. Sixth seminar for homogenization and quality control in climatological DB– Budapest 2008 Ongoing Research • Application of other methods • Pairwise comparisons / correction method • Daily homogenization and analysis

  19. Sixth seminar for homogenization and quality control in climatological DB– Budapest 2008 A spatial analysis of the homogenized DB • S mode PCA applied to monthly gridded series • Varimax Rotation • Hierarchical Cluster Analysis with the average linkage method A, B are two PCs and a, b are the associated EOFs

  20. Sixth seminar for homogenization and quality control in climatological DB– Budapest 2008 7 significant clusters were identified.

  21. Sixth seminar for homogenization and quality control in climatological DB– Budapest 2008 Thank you!

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