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BENCHMARK DATASET HOMOGENIZATION. A first test.

BENCHMARK DATASET HOMOGENIZATION. A first test. Contribution to the Working Groups Meeting of COST-HOME action, Tarragona, 9-11 March 2009. Enric Aguilar, Center on Climate Change, URV, Tarragona. C3-SNHT APPLICATION. New software (F95) ‏

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BENCHMARK DATASET HOMOGENIZATION. A first test.

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  1. BENCHMARK DATASET HOMOGENIZATION. A first test. • Contribution to the Working Groups Meeting of COST-HOME action, Tarragona, 9-11 March 2009 • Enric Aguilar, Center on Climate Change, URV, Tarragona.

  2. C3-SNHT APPLICATION • New software (F95)‏ • Detection (done) and taylored correction modules (almost done) • Reference selection (distance, correlation, overlap) • One homogenization for station: for each station/element/month-season-annual a special “network” is created and only the results for the main candidate are retained • Series are split until the most recent significant break is found and the remaining series is tested until no more breaks are found or the segment is too small • Breaks need to be inspected and a correction pattern created. This is better done with annual and seasonal averages (problem with benchmark; run over anomalies?)‏ • R-code for output inspection • WORK IN PROGRESS: • feed breaks to HOM; use weather types to calculate daily factors

  3. VISUAL INSPECTION STATISTICAL DETECTION BREAKS VALIDATION Network TEMP/SUR1/000001

  4. VISUAL INSPECTION • Saint-Cornier (06): large break around 1959 & missing 1945 • Chartres (03): large break around 1950 • Saint Georges (01): break around 1970 & missing 1945 • Groix (02) : break around 1955 & and missing 1945 • Rennes (04): break around 1985 & missing 1940

  5. STATISTICAL DETECTION • Monthly results are confusing and noisy • Seasonal are better (only 4!)‏ • Annual, optimum to start

  6. PLOTS FOR BREAK VALIDATION HOMOGENIZATION FOR SAINT-CORNIER Data series for main candidate and references. Red lines indicate breaks

  7. PLOTS FOR BREAK VALIDATION HOMOGENIZATION FOR SAINT-CORNIER Zeta-series for main candidate and references. Red lines indicate breaks

  8. PLOTS FOR BREAK VALIDATION HOMOGENIZATION FOR SAINT-CORNIER Data and Zeta-series for main candidate

  9. PLOTS FOR BREAK VALIDATION HOMOGENIZATION FOR SAINT-CORNIER test-values and break location

  10. PLOTS FOR BREAK VALIDATION HOMOGENIZATION FOR SAINT-CORNIER Histogram of Detected breaks, in all homogenizations where this station has participated

  11. PLOTS FOR BREAK VALIDATION HOMOGENIZATION FOR SAINT-CORNIER Detected breaks, drawn proportional to the largest one

  12. SAINT-GEORGES • Large break in 1948 • Smaller breaks after 1970 • Pattern: • BREAK 1948 • TREND 1948-1981 or BREAK 1970

  13. GROIX • Annual detects nothing • Z-plots point to 1950-1960 • Histogram plot indicates 1949 and 1955 or 1956 • They're detected in summer • Pattern: • BREAK 1949 • BREAK 1956

  14. GROIX • Question: is my decision influenced by the existence of larger breaks? • Plot 1 = no • Plot 2 = maybe!

  15. CHARTRES • Looking at annual + Spring (plotted)‏ • BREAK 1980 • BREAK 1948 (Clear)‏ • BREAK 1926 • BREAK 1919 (?)‏

  16. CHARTRES • SUMMER: non detected outlier (level is 3.5 sd) going in the oposite direction of a potential break: no detection!

  17. RENNES • ANNUAL: • BREAK 1990 • BREAK 1951 • OTHER POSSIBLE BREAKS: • 1919 & 1926 ... (remember last slide?) Influenced by others or margin effect? • ~ 1979 -1984 ==> forced by outlier

  18. GIEVRES • Breaks are small • BREAK 1985 • BREAK 1943 • MAYBE TREND 1943-END?

  19. SAINT CORNIER • BREAKS 1994 • BREAK 1959 • BREAK 1942 (missing?)‏ • BREAK 1928 (?)‏ Annual Summer: detection around 1935, but seems to be ~ 1928

  20. ILE-YEU • Annual does not detect breaks, but there is an evident (short) problem between 1931-1934 (2 breaks?)‏ • Winter (shown bottom pannel) and Spring identify: • BREAK 1963

  21. LA MOTE-ACHARD • Breaks have small amplitude. Visual inspecetion of z-series suggests: • TREND 1951-1980? • BREAK 1951 • BREAK 1939

  22. BIARD • BREAK ~ 1970? • BREAK 1943 • MANY OUTLIERS FOUND

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