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Radan HUTH Institute of Atmospheric Physics, Prague, Czech Republic
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Radan HUTH Institute of Atmospheric Physics, Prague, Czech Republic

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  1. Synoptic-climatological evaluation of COST733 circulation classifications: Principles and first results Radan HUTH Institute of Atmospheric Physics, Prague, Czech Republic

  2. GOAL • assess the synoptic-climatological applicability of classifications • i.e., how well they stratify surface weather (climate) conditions

  3. TOOL • 2-sample Kolmogorov-Smirnov test • equality of distributions of the climate element under one type against under all the other types x

  4. TOOL • at each station • classes for which the K-S test rejects the equality of distributions are counted • the larger the count, the better the stratification, the better the synoptic-climatological applicability

  5. EXAMPLE • 20 objective class’s over domain 00 (whole Europe) • + 6 subjective (and objectivized) catalogues (not assigned to any domain) • from the v1.0 release of COST733 database

  6. EXAMPLE • winter (DJF) • maximum temperature • 97 European stations (ECA&D database) • Jan 1958 – Feb 1993

  7. Hess&Brez. – individual types Note geographical coherence of regions of acceptance / rejection of the hypothesis

  8. Hess&Brez. – individual types

  9. Hess&Brez. – individual types

  10. Summary over types: %age of test rejections subjective + objectivized catalogues 100 % 85-99 % 70-84 % x <70 %

  11. Summary over types: %age of test rejections objective catalogues I. 100 % 85-99 % 70-84 % x <70 %

  12. Summary over types: %age of test rejections objective catalogues II. 100 % 85-99 % 70-84 % x <70 %

  13. BRIEF SUMMARY • considerable differences between class’s, but several common features • are they season- & variable-specific or more general ? • bad stratification at edges (but not all) of the domain • SW (W Iberian Peninsula) • SE (Balkans) • NE (N Norway) • E (W Russian border) • good stratification in • central Europe (N of the Alps) • W Europe (incl. Ireland and whole France) • S & central Scandinavia • Baltic countries (EE, LV, LT) • Iceland (!!!) • Verona – bad stratification for almost all class’s  likely data problem

  14. RANKING OF CLASS’S • methods ranked by the %age of rejected K-S tests (= well separated classes) at all stations individually • higher %age  better  lower rank • ranks averaged over stations for each classification • area mean rank  ranking of the classification

  15. RANKING OF CLASS’S • dependence on no. of classes • lower number  larger class sizes  smaller difference necessary for significance  more (higher %age) of rejections  better stratification

  16. RANKING OF CLASS’Slow number of classes (7 to 14)

  17. RANKING OF CLASS’Smoderate number of classes (17 to 22)

  18. RANKING OF CLASS’Shigh number of classes (26 to 42)

  19. PRELIMINARY CONCLUSIONS • synoptic-climatological applicability widely differs among class’s • synoptic (& objectivized) catalogues compete successfully with objective methods (although not originally designed for the large domain) • objectivized Hess-Brezowsky slightly better than original subjective catalogue • Hess-Brezowsky outperforms all objective methods with comparable no. of types

  20. PRELIMINARY CONCLUSIONS • tentatively recommendable class’s: • Enke & Spekat • Beck • T-mode PCA • objectivized Hess & Brezowsky • SANDRA • but: other seasons & other climate elements may lead to different results •  task for near future