Institut für Wasserbau Stuttgart Geodätisches Institut Stuttgart Institut für Meteorologie und Klimaforschung IMK-IFU SPP 1257 DIRECT WATERBALANCE An interdisciplinary approach towards the determination of large scale actual evapotranspiration and the evaluation of atmospheric moisture flux Sneeuw 1 N., W. Keller 1 , B. Devaraju 1 , M. Antoni 1 , M. Weigelt 1 , A. Bárdossy 2 , J. Riegger 2 , H. Kindt 2 , B. Fersch 3 , H. Kunstmann 3 1 Institute of Geodesy, Universität Stuttgart 2 Institute for Hydraulic Engineering, Universität Stuttgart 3 Institute for Meteorology and Climate Research IMK-IFU, Forschungszentrum Karlsruhe
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Institut für Wasserbau Stuttgart Geodätisches Institut Stuttgart Institut für Meteorologie und Klimaforschung IMK-IFU SPP 1257 DIRECT WATERBALANCE An interdisciplinary.
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Institut für WasserbauStuttgart
Geodätisches InstitutStuttgart
Institut für Meteorologie und Klimaforschung IMK-IFU
SPP 1257
DIRECT WATERBALANCE
An interdisciplinary approach towards
the determination of large scale actual evapotranspiration
and the evaluation of atmospheric moisture flux
Sneeuw1 N., W. Keller1, B. Devaraju1, M. Antoni1, M. Weigelt1, A. Bárdossy2,
J. Riegger2, H. Kindt2, B. Fersch3, H. Kunstmann3
1 Institute of Geodesy, Universität Stuttgart
2 Institute for Hydraulic Engineering, Universität Stuttgart
3 Institute for Meteorology and Climate Research IMK-IFU, Forschungszentrum Karlsruhe
Institut für WasserbauStuttgart
Geodätisches InstitutStuttgart
Institut für Meteorologie und Klimaforschung IMK-IFU
Project Structure
Geodesy
• Evaluation and
Correction of GRACE
Errors
Calculation of Mass
Variations for Climatic
Zones and Catchments
Hydrology
• Identification of Climatic
Zones and known
Hydrologic Signals
Determination of Water
Balance
(ETa, dS/dt, Q)
on large Catchments
Atmosphere
• Determination of
Atmospheric Water
Transport
Determination of large
scale source / sinks of
atmospheric moisture
Institut für WasserbauStuttgart
Geodätisches InstitutStuttgart
Institut für Meteorologie und Klimaforschung IMK-IFU
Evaluation Approach
Large Scale Water Balance for Catchments :
Hydrology GRACE Atmosphere
Hydrology :
• Meteorology : P = Padv + Pconv and ETa (Soil, Vegetation)
• amplitudes differ• in general congruence but for selected periods large differences possible
Modelled Atmospheric Mass VariationsAustralian mean JAN 20026 hours resolution
Institut für WasserbauStuttgart
Geodätisches InstitutStuttgart
Institut für Meteorologie und Klimaforschung IMK-IFU
0,4
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y = 1,2545x + 10,659
R2 = 0,3482
0
5
10
15
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25
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40
0 5 10 15 20
STDEV (dS / dt)
ST
DE
V (
dM
/ d
t)
GRACE Signal Variations
for catchments
for long time series when ETa <~ 15mm/mo
GRACE variations
Threshold = 10mm
GRACE Hydrology
Task for Atmosphere Research
Task for Geodesy
Institut für WasserbauStuttgart
Geodätisches InstitutStuttgart
Institut für Meteorologie und Klimaforschung IMK-IFU
Geodesy Tasks
Effect of filters: attenuation, biased estimation
• functional vs. stochastic• isotropic vs. anisotropic e.g. Han et al.
• filter parameter choice (e.g. cap radius) e.g. (Chen, Wilson, Famiglietti, Rodell; 2007)
• destriping or not e.g. (Swenson, Wahr; 2006)
• omission and commission errors e.g. (Gunter, Ries, Bettadpur, Tapley; 2006)
Effect of correlation/decorrelation
• propagation of full error VC matrix e.g. Schrama
• simulation of normal matrix structure e.g. Kusche
Effect of basin function e.g Wilson et al.
Institut für WasserbauStuttgart
Geodätisches InstitutStuttgart
Institut für Meteorologie und Klimaforschung IMK-IFU
Error Budgets: Wiener Filtering
But:• when is signal really signal?
• what is noise?
• anisotropic?
monthly deviation from long-term mean field
mean monthly deviation
power law fit through mean deviation
power law minus mean deviation
monthly formal errors
mean formal error
2
2 2l
ll l
sw
s n
ls
ln
Institut für WasserbauStuttgart
Geodätisches InstitutStuttgart
Institut für Meteorologie und Klimaforschung IMK-IFU
filters and windows
Institut für WasserbauStuttgart
Geodätisches InstitutStuttgart
Institut für Meteorologie und Klimaforschung IMK-IFU
some filtering effects
Institut für WasserbauStuttgart
Geodätisches InstitutStuttgart
Institut für Meteorologie und Klimaforschung IMK-IFU
some filtering effects
Institut für WasserbauStuttgart
Geodätisches InstitutStuttgart
Institut für Meteorologie und Klimaforschung IMK-IFU
Summary
• No systematic Correlation between Residuals of
GRACE Mass Changes and Hydrologic Storage Changes
• Significant Impact of Global Atmospheric Driving Data and
Spatial Resolution on MFD and Atmospheric Masses
• Significant Impact of Filter Choice (and Spectral Correlations)
on Mass Estimates and their Uncertainties
Use of Mass Constraints from Hydrology as Reference
for GRACE (25% area of land masses)
Institut für WasserbauStuttgart
Geodätisches InstitutStuttgart
Institut für Meteorologie und Klimaforschung IMK-IFU
End
Institut für WasserbauStuttgart
Geodätisches InstitutStuttgart
Institut für Meteorologie und Klimaforschung IMK-IFU
Mean Monthly Water Balance
-50
0
50
100
Ma
ss
Ch
an
ge
[m
m/M
o]
dM/dt
P-Q
ETa
Water Balance
Mean Monthly Behaviour Northern Sahara
Reasonable Annual Behaviour
Institut für WasserbauStuttgart
Geodätisches InstitutStuttgart
Institut für Meteorologie und Klimaforschung IMK-IFU
Monthly Values
-50
0
50
100
Mas
s C
hang
e [
mm
/Mo]
P-Q 2003
P-Q 2004
ETa 2003
ETa 2004
dM/dt 2003
dM/dt 2004
Water Balance
Monthly Behaviour Northern Sahara
Variations +/- 20% - 30% of Annual Amplitudes (for Tundra)
Institut für WasserbauStuttgart
Geodätisches InstitutStuttgart
Institut für Meteorologie und Klimaforschung IMK-IFU
GRACE Residuals
Monthly Residual of GRACE Global Solutions Release IV Nov 05
Relationship to Orbits ?
Institut für WasserbauStuttgart
Geodätisches InstitutStuttgart
Institut für Meteorologie und Klimaforschung IMK-IFU
GRACE Residuals
Monthly Residual of GRACE Global Solutions Release IV Destriped Nov 05
Relationship to Orbits ?
Institut für WasserbauStuttgart
Geodätisches InstitutStuttgart
Institut für Meteorologie und Klimaforschung IMK-IFU
Noise / Signal for GRACE
Stdev of GRACE Residual / GRACE Mean Annual Range
Stdev from 25% Mean
Institut für WasserbauStuttgart
Geodätisches InstitutStuttgart
Institut für Meteorologie und Klimaforschung IMK-IFU
Next StepsHydrology :
• Quantification of Hydrological Uncertainties• Selection of appropriate Reference Areas (dS/dt<10mm/mo)
• Correlations Hydrology - GRACE
Atmosphere : • Evaluation of Moisture Flux on Regional Scales• Evaluation of Regional Pressure Distrubutions
Geodesy :• filter optimization• improved error budgets• Investigation of correlations• functional modeling of residual signal with radial base functions• Correlations spatial vs. spectral• developing mass correction models for hydrological constraints
(25% of land masses)• incorporating regional atmospheric constraints