1. IUFRO_20051 Variations of land water storage over the last half century K. Laval, T. Ngo-duc, J. Polcher University PM Curie Paris/Lab Meteor Dyn /IPSL

2. IUFRO_20052 Land Water Balance Variation of land water in Land Surface Models: -Precipitation (highly variable) -Melting of Snow and Ice -Evapotranspiration -Total Runoff Runoff yields river discharge Y to the surface water Network:integration over a basin

3. IUFRO_20053 Outline Construction of 53-year atmospheric data to force LSM Models Results on river discharges (Mekong): Seasonal and interannual variations Preliminary results on water storage (Grace Mission): Influence of inundated and irrigated areas

4. IUFRO_20054 The ORCHIDEE land surface model of IPSL SECHIBA : surface energy and water balances (land and soil) STOMATE : surface biochemical processes LPJ : evolution of the vegetation and the carbon budget Only Sechiba is used in the simulations. Only Sechiba is used in the simulations. Inclusion of a routing scheme, which routes water to oceans through a cascade of linear reservoirs. Inclusion of a routing scheme, which routes water to oceans through a cascade of linear reservoirs. Ducoudre,N, K. Laval and A. Perrier, 1993: a new set of hydrological exchanges at the land atmosphere interface. J. of Climate,6248-273. Ducoudre,N, K. Laval and A. Perrier, 1993: a new set of hydrological exchanges at the land atmosphere interface. J. of Climate,6248-273.

5. IUFRO_20055 Forced simulation over 53 years Construction of 53-y forcing data and integrations of Land Surface Model Validation of river discharges

6. 6 Construction of NCC data NCEP/NCAR Reanalysis 6h; 1°.875; 1948-present NCEP NPRE NCRU NCC Interpolation to the grid 1°×1°, differences in elevation between the grids were taken into account CRU (Climate Research Unit) precipitation 0.5°×0.5°, 1901-2000 CRU (Climate Research Unit) temperature 0.5°×0.5°, 1901-2000 Radiation : SRB (Surface Radiation Budget) (NCEP/NCAR Corrected by CRU) 6-hourly, 1°x1°, 1948-2000 http://dods.lmd.jussieu.fr/cgi-bin/nph- dods/Dods/NCC/ (~40GB) Ngo-duc, T., J. Polcher and K. Laval (JGR, 2005)

7. 7 Validation The river discharge of the world's 10 biggest rivers Observed discharge  GRDC (Global Runoff Data Center)  Data at UCAR (the University Corporation for Atmospheric Research) Station Obidos 55.51°W, 1.95°S

8. IUFRO_20058 Amazon River Discharge OBS NCEP/NCAR NCC NCEP/NCAR OBS  quality of the NCC forcing data is improved compared to NCEP/NCAR  high flow in simulated mean seasonal signal is too early  the interannual signal is well described by the NCC experiment

9. IUFRO_20059 Seasonal signal of Mekong discharge at Pakse

10. IUFRO_200510 Annual Discharge simulated at Pakse

11. IUFRO_200511 Taylor diagram: Taylor diagram: NCEP and NCC 1. Amazon 2. Congo 3. Orinoco 4. Changjiang 5. Brahmaputra 6. Mississippi 7. Yenisey 8. Parana 9. Lena 10. Mekong Precipitation: most important improvement Temperature: significant effect only at high latitudes Radiation: improves discharge amplitudes

12. IUFRO_200512

13. IUFRO_200513 From Frappart et al submitted GJI.

14. IUFRO_200514 Irrigated and Inundated areas

15. IUFRO_200515 > 0.3 mm day -1 > 0.2 mm day -1

16. IUFRO_200516 Simulated Soil Moisture by Orchidee

17. IUFRO_200517 Mekong discharge at the mouth of the river 18500 16600

18. IUFRO_200518 GRACE Mission (Gravity Recovery And Climate Experiment GRACE, twin satellites launched in March 2002, measure the Earth's gravity field with unprecedented accuracy. This produces estimates of changes in water storage for given terrestrial regions.

19. IUFRO_200519 Water storage variation as simulated by 2 versions of Orchidee (with and without routine scheme ) and evaluated by Grace Mission (o). The routine scheme improves the simulated water storage

20. IUFRO_200520 Conclusions Orchidee is able to reproduce seasonal and interannual changes of continental water reservoirs. NCC data set was found reliable. The influence of inundated and irrigated areas seems substantial for the water budget of Mekong basin. Estimations from GRACE seem to confirm the role of ground water.

21. IUFRO_200521

22. 22 GRACEORCHIDEE with routing ORCHIDEE without routing Seasonal variations of continental water April/May – November 2002 The routing scheme improves the signals over tropical basins