L’Hydrologie Continentale vu par T/P, ERS, GRACE, … (LEGOS/GOHS)

Applications de l’Observation Spatiale à l’Hydrologie Continentale Technique Humidité des sols Eaux souterraines Neige Eaux de surface Imagerie visible *** (étendue) Imagerie radar Radiométrie micro-ondes ** (épaisseur) Altimétrie radar *** (hauteur d’eau) Gravimétrie spatiale *** (masse) Interférométrie radar *** (déformation de surface) Lidar Doppler ** (vitesse de surface) non testé

Bassin Amazonien Couverture de Topex/Jason (rouge) et ERS/Envisat (noir)  stations hydrographiques in situ

Station Virtuelle Trace du satellite Série temporelle de Mesure alti à 1/10 sec cycle 11 cycle 12 cycle 13 Trace du satellite FLEUVE Série temporelle de hauteurs d’eau 1993 2002

Rio Negro (Bassin de l’Amazone) --------------------------------------------------- Série temporelle de hauteurs d’eau à partir des données Topex/Poseidon 2002 1993

AMAZONE Débit (m3/s) Topex In situ différences

Lac Balbina (Amazonie) Hauteurs d’eau d’après Topex/Poseidon

Topex 1 BASSIN DU MEKONG 3 2 Plaine d’inondation 3 m

Réseaux hydrographiques in situ GRDC GRDC : Global Runoff Data Center

INVERSION OF GRACE GEOIDS FOR LAND HYDROLOGY C. Reigber, R. Schmidt (GFZ, Potsdam) G. Ramillien, A. Cazenave (LEGOS, Toulouse)

STEP 1 STEP 2 Global Models : Inversion for « De-correlation » Atmosphere : ECMWF(79-93), NCEP(79-96) Oceans : POCM(79-97),ORCA(92-99), MIT(85-96), ECCO assimilation (1993 -…) Soil moisture & Snow cover : LaD(81-98),GSWP(87-88),Huang(79-98) Observed monthly mean variations of the geoid A priori uncertainties of Models and GRACE obs. Inversion for « De-correlation » (Generalized least-squares matrix solving) STEP 1 Maps of geoid anomaly for each hydrological contribution Atmosphere Oceans Soil moisture Snow cover Predictive filtering of the spherical coefficients + compensation (elastic Earth’s response to surface loads) STEP 2 Distribution of surface water masses

GRACE geoids : time span

GRACE geoids (GFZ) April 2002 May 2002 November 2002

May-Nov. (seasonal cycle); Models Total land water (soil water + snow) LaD GSWP

May 2002-Nov.2002 (seasonal cycle) Total land water (soil water + snow) Lad(1rst guess) GSWP (1rst guess)

May02-Nov02 (seasonal cycle) GRACE geoids from CSR Total land water (soil water + snow)

Seasonal cycle of total land waters (April+May) 2002 minus November 2002 GFZ geoids Same solution whatever the first guess

Residuals : GRACE(GFZ) minus solution; seasonal cycle LaD as 1rst guess GSWP as 1rst guess

Demande Budgétaire 2004

) The solution is computed by solving the linear equation: : solution vector formed by the list of all spherical harmonic coefficients to be solved : vector formed with GRACE-derived geoid coefficients : vector formed by the list of all spherical harmonic coefficients of the ‘first guess’ : matrix composed of 4 diagonal blocks for separating the 4 reservoirs contributions : covariance matrices of the ‘a priori’ GRACE errors and a priori model uncertainties : covariance matrix which describes the statistical properties of the water mass variations in the ‘k-th’ reservoir