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WP3 Task 3.2 First experience in T3.2
Luciana Fenoglio-Marc (P14) Institute of
Physical Geodesy, Darmstadt University of
Technology ESEAS-RI WP1 - WP3 Meeting, Darmstadt
28-29 January 2004
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TASK / DELIVERABLES / MILESTONES
(1.1)
TASK 3.2 a) Estimate dominating spatial and
temporal variations on interannual to decadal
time-scales (P2, P5, P14) b) ...and their
relationship with physical phenomena like El
Nino/La Nina (P2, P5, P14) c) Interpolate sparse
TG data to grids using EOF derived from satellite
altimetry (P2,P14) DELIVERABLES (contributes
with T3.3 to) D3.2 Global interpolated data set
of decadal variations from TG data using EOF
derived from T/P altimetry MILESTONES M3.2
EOF Analysis completed (18 month) M3.3
Empirical Model of decadal variability (with
T3.3)
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1. Comparison of results at control stations (9)
as in WP3.1 (May 2003)
2. Results
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(1.0)
Comparison of results at CT
Partners P2, P5, P14
To do 1) correlation at inter-annual and
decadal freq. of climatic indices and TG (P2, P5,
P14) 2) correlation at inter-annual freq of
Altimetry and TG (P2, P14)
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(1.1)
Comparison of results at CT
Monthly - linear trend - seasonal residuals
Single field residuals (NAO, SOI, PDO, TG, ALT)
1. Simple correlation of residuals between NAO,
SOI, PDE and TG, /between ALT and TG 2.
lag-correlation of residuals 3. Cross-spectrum
of residuals
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(1.2)
Comparison of results at CT
- detailed definition of input / outputs - -
minor problems in formulation (necessary
details) --- general good agreement
Problems, discussion and Improvements 1)
Different start/end of series chosen
(criteria?) 2) Interpolation methods used ( P2
interpolates monthy val., P5 interpolates
residuals) HOW is in Dataset TG WP3.1 ? 3)
Parameters to be estimated - standard error of
estimated trend - significance of
correlation 4) Parameters for X Spectrum (P5,
P14) - cross amplitude spectrum A, -
squared coherence W - gain G and phase F
of dep y v x 5) order (XY or YX)
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(2.0)
Results last decade
Table 1. Linear trends in last decade at the 9 TG
control-stations
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(2.1)
Results last decade
Table 2. Pearson correlation between indices and
TG control-stations
1. Significance with 120 points is 0.180 with DF
n-2 2. NAO in European region and Atlantic 3.
Stockholm and Trieste of opposite sign 4. SOI in
Honolulu and San Francisco 5. PDO in San
Francisco
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Lag correlation between 4 indexes and Stockholm
in 1992-2002
(2.2)
NAO
SOI
PDO
NPI
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(2.3)
Results last decade
NAO
SOI
PDO
Figure 1. Lag-correlation with NAO, SOI, PDO
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(2.4)
Results last decade
Figure 2. Cross-spectrum NAO and Stockholm,
1992-2001
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(2.5)
Results last decade
Figure 2 bis
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(2.6)
Results last decade
Figure 3. Cross-spectrum ALT and TG at
Stockholm, 1992-2001
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(2.7)
Comparison altimetry and tide gauge data
- Trend - correlation of inter-annual and
long-term sea level change
- Selection of time series to be compared with
tide gauge (P2,P14) is different P14 closest
point in the altimetric grid - Need of
comparison of altimetry map solutions with
different resolutions already prepared and
estimation of differences
Table 3 Correlation between altimetry and tide
gauges in 1993-2001 and trend (mm/yr)
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Conclusions
(3.0)

3 3
0) Some points to be checked in preliminary work
(e.g. parameters for good agreement between TG
and altimetry data) 1) Define further
collaboration in Task 3.2 between P2, P5 and P14
2) Selection of test area (European Seas and
Atlantic)
3) EOF with tide gauge data in the last decade
and compare with EOF from altimetry use TG
dataset prepared by WP3.1
4) Relative importances of index in various
regions using the TG

5) Investigate this and methods for interpolation
from TG to open ocean in the past
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(4.1)

Caracteristics for the best agreement
Parameters 1. Distance (km) 2. Std deviation
of the differences (small) 3. Std devation of
the time-series () 4. Correlation coefficient
(1)
Tab.4 Difference of the sea level change
(linear-part) from pointwise data
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Conclusions
(6.1)

1) Harmonisation of the data for evaluation of
relative bias und drift between the
altimetermissions and for monitoring of the
altimeter instrument (Instrumental Drift,
environmental corrections)
2) Cross-calibration at same time and
different locations (DXT) for altimetry and TG
stations (long-term variability)
3) Average and pointwise differences of the sea
level heights between TP and TG (2 Methods
4) The averaged long-term change from altimetry
and TG are in agreement (regional sea level
variability, results depend on the lenght of the
time-series
5) Parameters characterising a good agreement
between TG and altimetry data.
SONEL data in nord-west Mediterranean Sea show
the best agreement
6) Cross-Calibration of Envisat altimeter
more data required for the statistical analysis
7) DXT as external Check, TG für Zeitraum lt 1991