kaiyuan y. li and dennis p. lettenmaier university of washington
DESCRIPTION
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. Outline. What is CLM? What are the problems with CLM? How is VIC fitted to CLM? How does the upgraded CLM work?. - PowerPoint PPT PresentationTRANSCRIPT
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
Outline
What is CLM? What are the problems with CLM? How is VIC fitted to CLM? How does the upgraded CLM work?
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).
CLM: data structure
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.
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).
CLM EvaluationThe FIFE Prairie Site (39.0ºN 96.5ºW)
• CLM overestimates surface runoff;• CLM underestimates latent heat and soil moisture contents.
CLM EvaluationThe 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.
CLM EvaluationThe Valdai Grassland Site (57.6ºN 33.1ºE)
• CLM poorly simulated soil moisture content.
CLM Evaluation The HAPEX-MOBILHY Soybean Site (43.7ºN 0.1ºW)
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.
CLM EvaluationTorne-Kalix Basin
• CLM tends to overestimate runoff peak for most basins;• CLM tends to melt snow earlier than observed.
CLM EvaluationArkansas and Red river basin
CLM EvaluationArkansas and Red river basin – Cont.
CLM EvaluationArkansas and Red river basin – Cont.
• CLM tend to overestimate runoff
CLM Evaluation The Colorado river basin
CLM Evaluation The Colorado river basin – Cont.
CLM Evaluation The Colorado river basin – Cont.
• CLM overestimated runoff;
• CLM melt snow one month earlier;
CLM EvaluationConclusions
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.
Upgrading CLMIncorporation of the VIC surface runoff and
baseflow schemes
10-Layer CLM 3-Layer VIC
Fixed Depth Dynamic Depth
VIC Upper Layer
VIC Lower Layer
Diagram: Matching CLM layer scheme to VIC Layer scheme
3.43 m
10-Layer CLM 3-Layer VIC
Fixed Depth Dynamic Depth
VIC Upper Layer
VIC Lower Layer
Diagram: Matching CLM layer scheme to VIC Layer scheme
3.43 m
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 CLMIncorporation of the VIC surface runoff and baseflow
schemes – Cont.
Performance testing of Upgraded CLM
The Arkansas-Red basin
Performance testing of Upgraded CLM
The Arkansas-Red basin – Cont.
Performance testing of Upgraded CLMThe Colorado basin
Performance testing of Upgraded CLM
The Colorado basin – Cont.
Performance testing of Upgraded CLM
The FIFE Prairie Site (39.0ºN 96.5ºW)
Performance testing of Upgraded CLM
The FIFE Prairie Site (39.0ºN 96.5ºW) – Cont.
Performance testing of Upgraded CLM
The ABRACOS Forest Site (10.1ºS 61.9ºW)
Performance testing of Upgraded CLM
The ABRACOS Forest Site (10.1ºS 61.9ºW) – Cont.
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.
AcknowledgementTed BohnFengge SuJenny AdamJoanna GaskiChunmei ZhuNiklas ChristensenMariza Costa-CbralNathalie VoisinKostas AndreadisAlan HamletLan Cuo