1. Upgrading Community Land Model (CLM) Hydrology Incorporation of the VIC Surface Runoff and Baseflow Schemes Kaiyuan Y. Li and Dennis P. Lettenmaier University of Washington

2. Outline  What is CLM?  What are the problems with CLM?  How is VIC fitted to CLM?  How does the upgraded CLM work?

3. What is CLM?  Stands for Community Land Model (used to be Common Land Model);  Community-developed land surface model: lead by NCAR in collaboration with universities;  Intended to be coupled into CAM or CCSM;  A framework into which other land surface models can be feasibly incorporated;  Professional software written in FORTRAN90 (similar to C with pointer and dynamic memory);  Optimum performance on both cache-dependent and vector- based computational platforms (parallel computing).

4. CLM: data structure

5. CLM: functionalities Vegetation composition, structure, and phenology. Absorption, reflection, and transmittance of solar radiation. Absorption and emission of longwave radiation. Momentum, sensible heat (ground and canopy), and latent heat (ground evaporation, canopy evaporation, transpiration) fluxes. Heat transfer in soil and snow including phase change. Canopy hydrology (interception, throughfall, and drip). Snow hydrology (snow accumulation and melt, compaction, water transfer between snow layers) Soil hydrology (surface runoff, infiltration, subsurface drainage, redistribution of water within the column). Stomatal physiology and photosysnthesis. Lake temperatures and fluxes. Routing of runoff from rivers to ocean. Volatile organic compounds. Vegetation dynamics and carbon cycle -- coming soon.

6. CLM Hydrology  Canopy hydrology Interception; Throughfall; Drip.  Soil Hydrology Surface runoff (Based on TOPMODEL); Baseflow; Soil water (based on Richard’s flow equation).  Snow Hydrology Based on Jordan (1991).

7. CLM Evaluation The FIFE Prairie Site (39.0ºN 96.5ºW) CLM overestimates surface runoff; CLM underestimates latent heat and soil moisture contents.

8. CLM Evaluation The ABRACOS Forest Site (10.1ºS 61.9ºW) CLM overestimated surface runoff; CLM underestimated latent heat and overestimated sensible heat; CLM poorly simulated soil moisture and evapotranspiration.

9. CLM Evaluation The Valdai Grassland Site (57.6ºN 33.1ºE) CLM poorly simulated soil moisture content.

10. CLM Evaluation The HAPEX-MOBILHY Soybean Site (43.7ºN 0.1ºW)

11. CLM Evaluation The HAPEX-MOBILHY Soybean Site (43.7ºN 0.1ºW) – Cont. CLM overestimated runoff; CLM undersimulated latent heat and overestimated sensible heat; CLM poorly simulated soil moisture content.

12. CLM Evaluation Torne-Kalix Basin CLM tends to overestimate runoff peak for most basins; CLM tends to melt snow earlier than observed.

13. CLM Evaluation Arkansas and Red river basin

14. CLM Evaluation Arkansas and Red river basin – Cont.

15. CLM tend to overestimate runoff

16. CLM Evaluation The Colorado river basin

17. CLM Evaluation The Colorado river basin – Cont.

18. CLM overestimated runoff; CLM melt snow one month earlier;

19. CLM Evaluation Conclusions  CLM tends to overestimate runoff;  CLM tends to melt snow earlier;  CLM poorly simulates soil moisture contents;  In general, VIC performs better than CLM in terms of hydrologic predictions;  Improvements of CLM are expected by incorporating some aspects of VIC hydrologic parameterizations into CLM.

20. Upgrading CLM Incorporation of the VIC surface runoff and baseflow schemes 10-Layer CLM3-Layer VIC Fixed Depth Dynamic Depth VIC Upper Layer VIC Lower Layer Diagram: Matching CLM layer scheme to VIC Layer scheme 3.43 m

21.  The Upgraded CLM retains: Data structure; Input and output format; Model structure.  The Upgraded CLM requires 5 VIC parameters: Upper layer depth (first plus second layer in VIC-3L); b: Infiltration parameter; Ws: Fraction of maximum soil moisture content when baseflow occurs; Dsmax: Maximum velocity of baseflow; Ds: Fraction of Dsmax where non-linear baseflow occurs. Upgrading CLM Incorporation of the VIC surface runoff and baseflow schemes – Cont.

22. Performance testing of Upgraded CLM The Arkansas-Red basin

23. Performance testing of Upgraded CLM The Arkansas-Red basin – Cont.

24. Performance testing of Upgraded CLM The Colorado basin

25. Performance testing of Upgraded CLM The Colorado basin – Cont.

26. Performance testing of Upgraded CLM The FIFE Prairie Site (39.0ºN 96.5ºW)

27. Performance testing of Upgraded CLM The FIFE Prairie Site (39.0ºN 96.5ºW) – Cont.

28. Performance testing of Upgraded CLM The ABRACOS Forest Site (10.1ºS 61.9ºW)

29. Performance testing of Upgraded CLM The ABRACOS Forest Site (10.1ºS 61.9ºW) – Cont.

30. Performance testing of Upgraded CLM Conclusions The Upgraded CLM, into which VIC runoff parameterization is incorporated, performs significantly better than original CLM; The Upgraded CLM requires only 5 VIC parameters, which are transferable to CLM without massive calibration although some systematical adjustment may be required for some basins; The enhancement of the CLM snow model remains to be done.

31. Acknowledgement Ted Bohn Fengge Su Jenny Adam Joanna Gaski Chunmei Zhu Niklas Christensen Mariza Costa-Cbral Nathalie Voisin Kostas Andreadis Alan Hamlet Lan Cuo