Water mass changes inferred by gravity field variations with GRACE
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Water mass changes inferred by gravity field variations with GRACE E. Fagiolini 1 , Ch. Gruber 1 , H. Apel 2 , N. V. Dung 2 , A. Güntner 2 (1) GFZ, 1.2 Global Geomonitoring and Gravity Field (2) GFZ, 5.4 Hydrology EGU 2013, Vienna, Austria
Transcript of Water mass changes inferred by gravity field variations with GRACE
Water mass changes inferred by gravity field variations with GRACE
E. Fagiolini1, Ch. Gruber1, H. Apel2, N. V. Dung2, A. Güntner2
(1) GFZ, 1.2 Global Geomonitoring and Gravity Field
(2) GFZ, 5.4 Hydrology
EGU 2013, Vienna, Austria
Overview
Gravity field determination: RL05, RBF, Kalman.
Characteristics and potentiality.
Comparisons with global hydrological model (WGHM).
Regional time series.
Mekong delta.
RL05, RBF, Kalman Inputs and post-filtering
KBRR LEVEL 1B
EPOSOC dynamic orbit processing
AOD1B atmosph. ocean
TIDES solid E. direct t. ocean t.
EIGEN6C static
EIGEN6C annual semiannualtrends
WGHM monthly
Gauss 200 km
Kusche DDK2 ~340 km
RL05
RBF
Kalman (daily)
stochastic
• RL05: standard dynamic approach (spherical harmonics).
• RBF: radial basis function (Poisson kernel), boundary value problem, regularized (Tikhonov) inversion of 1 month accumulated in-situ data.
• KALMAN daily: Kalman filter, prediction matrix.
Seasonal Amplitude
Annual Phase
Trends
Offset to background
Degree variances: spatial resolution
Correlation with hydrology
r( RL05 , WGHM ) , p < 0.005 r( RBF , WGHM ) , p < 0.005
Correlation differences
r( RL05 , WGHM) - r(RBF , WGHM)
RBF RL05
Amplitude differences
ARL05 – AWGHM ARBF – AWGHM
Amplitude differences
RBF RL05
| ARBF – AWGHM | - | ARL05 – AWGHM |
Alps
Bangladesh
Tigris
Deserts: noise level [Ewh]
Mekong Delta
Dung et al.“Multi-objective automatic calibration of hydrodynamic models utilizing inundation maps and gauge data” (2011), Hydrology and Earth System Sciences.
Comparing mass changes from GRACE with explicit hydraulic simulations of the large scale annual inundation volume (red points: calibration).
Mekong Delta
how to choose a good mask? leakage in / leakage out
Mekong Delta
Mekong Delta
Mekong Delta
Outlook and conclusion
• Intention: higher spatial and temporal resolution by radial basis function and Kalman filtering.
• Different approaches: similar results and new potentiality.
• Conversion of KBRR to in-situ gravitational acceleration works well.
• Relatively low computational cost.
• More signal power in short wavelength.
• Global and regional solutions feasible.
• Very good agreement with hydrologic modeling in Mekong Delta.
