BENCHMARK DATASET HOMOGENIZATION. A first test.

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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.

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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

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Network TEMP/SUR1/000001

• VISUAL INSPECTION
• STATISTICAL DETECTION
• BREAKS VALIDATION

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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

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STATISTICAL DETECTION

• Monthly results are confusing and noisy
• Seasonal are better (only 4!)?
• Annual, optimum to start

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PLOTS FOR BREAK VALIDATION
HOMOGENIZATION FOR SAINT-CORNIER Data series
for main candidate and references. Red lines
indicate breaks
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PLOTS FOR BREAK VALIDATION
HOMOGENIZATION FOR SAINT-CORNIER Zeta-series
for main candidate and references. Red lines
indicate breaks
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PLOTS FOR BREAK VALIDATION
HOMOGENIZATION FOR SAINT-CORNIER Data and
Zeta-series for main candidate
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PLOTS FOR BREAK VALIDATION
HOMOGENIZATION FOR SAINT-CORNIER test-values
and break location
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PLOTS FOR BREAK VALIDATION
HOMOGENIZATION FOR SAINT-CORNIER Histogram of
Detected breaks, in all homogenizations where
this station has participated
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PLOTS FOR BREAK VALIDATION
HOMOGENIZATION FOR SAINT-CORNIER Detected
breaks, drawn proportional to the largest one
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SAINT-GEORGES

• Large break in 1948
• Smaller breaks after 1970
• Pattern
• BREAK 1948
• TREND 1948-1981 or BREAK 1970

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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

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GROIX

• Question is my decision influenced by the
  existence of larger breaks?
• Plot 1 no

• Plot 2 maybe!

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CHARTRES

• Looking at annual Spring (plotted)?
• BREAK 1980
• BREAK 1948 (Clear)?
• BREAK 1926
• BREAK 1919 (?)?

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CHARTRES

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

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RENNES

• ANNUAL
• BREAK 1990
• BREAK 1951
• OTHER POSSIBLE BREAKS
• 1919 1926 ... (remember last slide?)
  Influenced by others or margin effect?
• 1979 -1984 gt forced by outlier

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GIEVRES

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

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SAINT CORNIER

• BREAKS 1994
• BREAK 1959
• BREAK 1942 (missing?)?
• BREAK 1928 (?)?

Annual
Summer detection around 1935, but seems to be
1928
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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

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LA MOTE-ACHARD

• Breaks have small amplitude. Visual inspecetion
  of z-series suggests
• TREND 1951-1980?
• BREAK 1951
• BREAK 1939

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BIARD

• BREAK 1970?
• BREAK 1943
• MANY OUTLIERS FOUND