River routing at the global scale: Application to Climate Model output Stefan Hagemann Max Planck Institute for Meteorol

1. River routing at the global scale: Application to Climate Model output StefanHagemann Max Planck Institute for Meteorology, Hamburg

2. Closure of water balance between atmosphere and ocean in a coupled AO-GCM Impact of climate change on river flow Validation of the simulated hydrological cycle in climate models River routing required

3. Hydrological Cycle D. Gerten, PIK

4. Atmosphere MPI-ESM: Processes Sun Emissions Dynamics Aerosols Chemistry Land Surface Dust DMS CO2 MomentumEnergyWater Hydrology Photosynthesis Phenology Respiration Ocean Dynamics Sea-ice Biology Chemistry River runoff

5. Atmosphere ECHAM HAM MESSy/MOZART MPI-ESM: model components Sun Emissions Dust DMS CO2 JSBACH Land MomentumEnergyWater HD model PRISMcoupler MPI-OM HAMOCC Ocean

6. Concentrations (GHG, SO4) ECHAM5 T63L31 Sun MomentumEnergyWater ECHAM5 HD PRISMcoupler MPI-OM 1.5°L40 IPCC simulation:GCMmodel components

7. Lateral Soil Water Fluxes 1/2 º 1/6 º 1 d 1 h dx HD Model (Hydrological Discharge) Soil Hydrology Scheme Surface Runoff Overland Flow Hagemann & Dumenil (1998), Clim. Dyn. 14 Hagemann & Dumenil Gates (2001), J Geo. Res. 106 State of the art discharge model Applied and validated on global scale at 1/2 deg. Part of ECHAM5-MPIOM Time step: 1 day (internally 6 hours for riverflow) European version by Kotlarski: k = f (dx, innerslope, wetlands, lakes) Drainage Baseflow k = f (dx) Riverflow Gridbox Outflow Gridbox Inflow k = f (dx, dh/dx, wetlands, lakes)

8. Problems in HD model applications • 0.5 degree resolution is a good compromise beween the large-scale meteorological and the small-scale hydrological processes • Creation of realistic model orography is time consuming •  Interpolation of climate model input required • Climate models often do not archive surface runoff and drainage separately •  Land Surface Hydrology Model (LHSM) required

9. RCM Precipitation, Evaporation & 2m Temperature(daily values) Interpolation to 0.5 degree SimplifiedLand surface scheme Discharge HydrologicalDischarge model SL scheme/HD model LSHM as used in PRUDENCE Surface Runoff Drainage

10. Precipitation & 2m Temperature Snowpack Land Surface Single Soil Layer Drainage Runoff The SL Scheme Snow Rain Snowmelt Throughfall (Simplified Land surface scheme) Infiltration Evapotranspiration Time Step: 1 day Hagemann & Dümenil Gates, 2003

11. Precipitation & 2m Temperature Snowpack Land Surface Single Soil Layer Drainage Runoff The SL Scheme Evapotranspiration Snow Rain Snowmelt Throughfall (Simplified Land surface scheme) Infiltration Time Step: 1 day Hagemann & Dümenil Gates, 2003

12. Model validation and intercomparison Example: PRUDENCE 50 km x 50 km Current climate: 1961-1990 Future climate: A2 scenario 2071-2100 Hagemann & Jacob, Climatic Change,2007 Application to regional climate models

13. Baltic Sea catchment Elbe Rhine Danube

15. Discharge 1961-90 Large Spread

16. DischargeChanges 2071-2100

18. SL scheme forced by CRU2 data of precipitation and temperature for 1961-90 (Spin-up 1960). Daily variations are taken from ERA40 Application to observations and GCMs

19. A A A Baltic Sea A A A Danube Amur Mississippi Yangtze Kiang Nile Amazon Ganges/Brahmaputra Congo Parana Murray A = 6 largest Arctic Rivers = Mackenzie, N Dvina, Ob, Yenisey, Lena, Kolyma Large catchments are considered

20. Validation of the hydrological cycle

21. Validation of the hydrological cycle

22. Effect of Interpolation on SL scheme hydrology

23. Effect of Interpolation on SL scheme hydrology

24. Effect of Interpolation on SL scheme hydrology

25. Application to GCM: MPI-M IPCC simulations • Historical Climate (1860 – present), Focus: 1961-1990 • Scenarios (present to 2100), Focus: 2071-2100 • Low emission scenario: B1 • Moderate emission scenario: A1B • High emission scenario: A2 • GCM: ECHAM5 / MPI-OM • 3 ensemble members for historical control simulation and each scenario • Horizontal Resolution of ECHAM5: T63 ~ 200 km • Forcing with observed / prescribed (for scenarios) concentrations of CO2, Methane, N2O, CFCs, Ozone (Tropos-/Stratosphere), Sulfate Aerosols (direct and 1. indirect effect)

26. Vertical fluxes by GCM or by SL scheme

27. Vertical fluxes by GCM or by SL scheme

28. Implication on projected changes of discharge

29. Summary • Problems in river routing • Interpolation from climate model grid to 0.5 grid required • Often a Land Surface Hydrology Model (LHSM) is required to force river routing model • Simulated discharge largely depends on the quality of precipitation and snowmelt used as forcing • Available discharge observations (e.g. from GRDC) often end in the 80s • Future Work • One aim of WATCH is to provide global LSHMs and methods to use forcing from climate models • These LSHMs shall include river routing, irrigation, dams, and groundwater schemes

30. © Canadian Space Agency, 1999 Thank you for your attention!

31. Climate Change

32. Climate Change

33. Climate Change

34. Climate Change

35. Summary of IPCC results • Trends for future climate (2071-2100 compared to 1961-90) • Pronounced changes of the hydrological cycle in all 3 scenarios, B1 changes tend to be smaller than for A1B and A2 whose changes are quite similar • Regional characteristics • High northern latitudes: Strongest warming in winter, generally enhanced hydrological cycle • Central Africa: Generally enhanced hydrological cycle • Pronounced drying in southern South Africa, southern Australia, and Mediterannean throughout the year • Drying in the dry seasons/Wetting in wet seasons for Danube (summer/winter), Indian and East Asian monsoon area (winter/summer), Amazon (summer-early fall/winter-spring)

36. PRUDENCE: Runoff

37. Precipitation 1961-90 Common RCM problems

38. PRUDENCE: Runoff changes