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.
Jan 03, 2016
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)
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
Network TEMP/SUR1/000001
VISUAL INSPECTIONSTATISTICAL DETECTION
BREAKS VALIDATION
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
STATISTICAL DETECTION
Monthly results are confusing and noisy
Seasonal are better (only 4!)
Annual, optimum to start
PLOTS FOR BREAK VALIDATION
HOMOGENIZATION FOR SAINT-CORNIER Data series for main candidate and references. Red lines indicate breaks
PLOTS FOR BREAK VALIDATION
HOMOGENIZATION FOR SAINT-CORNIER Zeta-series for main candidate and references. Red lines indicate breaks
PLOTS FOR BREAK VALIDATION
HOMOGENIZATION FOR SAINT-CORNIER Data and Zeta-series for main candidate
PLOTS FOR BREAK VALIDATION
HOMOGENIZATION FOR SAINT-CORNIER test-values and break location
PLOTS FOR BREAK VALIDATION
HOMOGENIZATION FOR SAINT-CORNIER Histogram of Detected breaks, in all homogenizations where this station has participated
PLOTS FOR BREAK VALIDATION
HOMOGENIZATION FOR SAINT-CORNIER Detected breaks, drawn proportional to the largest one
SAINT-GEORGES
Large break in 1948
Smaller breaks after 1970
Pattern: BREAK 1948 TREND 1948-1981 or
BREAK 1970
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
GROIX Question: is my decision
influenced by the existence of larger breaks?
Plot 1 = no
Plot 2 = maybe!
CHARTRES
Looking at annual + Spring (plotted)
BREAK 1980 BREAK 1948 (Clear) BREAK 1926 BREAK 1919 (?)
CHARTRES
SUMMER: non detected outlier (level is 3.5 sd) going in the oposite direction of a potential break: no detection!
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
GIEVRES
Breaks are small
BREAK 1985
BREAK 1943
MAYBE TREND 1943-END?
SAINT CORNIER
BREAKS 1994
BREAK 1959
BREAK 1942 (missing?)
BREAK 1928 (?)
Annual
Summer: detection around 1935, but seems to be ~ 1928
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
LA MOTE-ACHARD
Breaks have small amplitude. Visual inspecetion of z-series suggests:
TREND 1951-1980?
BREAK 1951
BREAK 1939
BIARD
BREAK ~ 1970?
BREAK 1943
MANY OUTLIERS FOUND