Transcript Slide 1

Addition of the CLM3 LandSurface Model to WRF
Jimy Dudhia (MMM/NCAR)
Ruby Leung (PNNL)
Tom Henderson (MMM/NCAR)
Mariana Vertenstein (CGD/NCAR)
Gordon Bonan (CGD/NCAR)
Current LSMs in WRF
 Noah LSM (NCEP/NCAR/AFWA)
 RUC LSM (FSL)
 5-layer soil model (NCAR)
Why another LSM?
 Beneficial in regional climate model applications
driven by CCSM boundaries (downscaling climate
scenarios)
 Want to use the same physics as CCSM
 CLM3 LSM
 CAM3 radiation
 Expertise with CLM3 is here at NCAR
 Bonan, Vertenstein and others
Community Land Model 3.0
 Land component of the Community Climate
System Model (CCSM)
 Actively under development
 Technical Description of the Community Land
Model
 Oleson, Dai et al. (May 2004)
 NCAR/TN-461+STR (online PDF file)
Community Land Model
What is the contribution of land surface processes to seasonal-tointerannual variability in climate and atmospheric CO2?
• Snow
• Soil water
• Leaf phenology (the seasonal emergence and senescence of leaves)
• Photosynthesis and stomatal conductance
What is the contribution of land surface processes to climate
sensitivity (paleoclimates, future climate)?
Note: The CLM is not designed
specifically for coupling to WRF, but
there is no fundamental difference
between land models for climate models
and NWP models. Both are 1-D models of
the soil-plant-atmosphere system. They
differ primarily in the complexity with
Research tool is the Community Land Model
which they represent meteorological,
hydrological, and ecological processes and
• Land model for Community Climate System Model
how they utilize satellite data
• Partnership among NCAR, universities, and government labs through
• Hydrologic cycle
• Carbon and nitrogen cycles
• Mineral aerosols
• Vegetation dynamics
• Land use and land cover change
the CCSM land model working group
Ongoing Activities
Ecology and biogeochemistry
• Carbon and nitrogen cycles
• Vegetation dynamics
• Leaf phenology
• Fire
• Mineral aerosols
• Biogenic volatile organic compounds
Land use and land cover change
• Agroecosystems
• Urbanization
• Soil degradation
• Historical and future land cover datasets driven by population change
Hydrology
• Global Land-Atmosphere Coupling Experiment (GLACE)
• Watershed processes
• River flow and biogeochemistry
• Water isotopes
High resolution CLM
• Subgrid orography
• Downscaling
• WRF
Community support
The model simulates a variety of ecological, biogeochemical,
and hydrological processes as climate feedbacks that are
traditionally considered when assessing the impact of climate
change. The model blurs the distinction between climate
feedbacks and climate impacts.
CLM And WRF: Issues
Inclusion of CLM in WRF provides an important scientific opportunity for
NCAR and the atmospheric (global, regional) modeling communities:
• Same land model for use with both a global climate model (CCSM) and a
regional model (WRF)
• New terrestrial science for WRF (e.g., carbon cycle, land use, BVOCs)
But …
Science
Are there common experiments that should be done with CCSM and WRF?
Can CLM meet the needs of data assimilation?
Software engineering
Surface datasets for WRF grids
Initial datasets
How to maintain compatibility of CCSM and WRF CLMs
Main Features of CLM3
 Surface Heterogeneity
 3 levels of grid-cell sub-division
 Landunits (5 types currently)
 Vegetated, Glacier, Lake, Wetland, Urban
 Columns (1 currently)
 multi-layer soil and snow column in Vegetated Landunit
 Plant Functional Types (4 PFTs currently/column)
 % of vegetation types in Vegetated Landunit
Nested Hierarchy of Data Structures in CLM3
15 Plant Functional Types
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Needleleaf Evergreen Tree - Temperate
Needleleaf Evergreen Tree - Boreal
Needleleaf Deciduous Tree - Boreal
Broadleaf Evergreen Tree - Tropical
Broadleaf Evergreen Tree - Temperate
Broadleaf Deciduous Tree - Tropical
Broadleaf Deciduous Tree - Temperate
Broadleaf Deciduous Tree - Boreal
Broadleaf Evergreen Shrub - Temperate
Broadleaf Deciduous Shrub - Temperate
Broadleaf Deciduous Shrub - Boreal
C3 Arctic Grass
C3 Grass
C4 Grass
Crop1/Crop2
Soil Layers
 10 soil layers
 mid-points near 0.7, 2.8, 6.2, 11.9, 21.2, 36.6,
62.0, 104, 173, 286 cm
 Up to 5 snow layers on top
Biogeophysical Processes
 Vegetation composition, structure, phenology
 Absorption, reflectance, 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 the soil and snow including phase
changes
Biogeophysical Processes (cont’d)
 Canopy hydrology (interception, throughfall and drip)
 Snow hydrology (snow accumulation and melt,
compaction, water transfer between snow layers)
 Soil hydrology (surface runoff, infiltration, sub-surface
drainage, redistribution of water within the columns)
 Stomatal physiology and photosynthesis
 Lake temperatures (multi-layer) and fluxes
 Routing and runoff from rivers to ocean (not in WRF yet)
 Biogenic volatile organic compounds (BVOCs) (could be
coupled to WRF-Chem)
Community Land Model
Reflected Solar
Radiation
Absorbed Solar
Radiation
Photosynthesis
Sensible Heat Flux
Latent Heat Flux
Longwave Radiation
Hydrology
Precipitation
Evaporation
Momentum Flux
Wind Speed
0
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Interception
Canopy Water
Transpiration
Emitted Longwave Radiation
Diffuse Solar
Radiation
Biogeophysics
Throughfall
Stemflow
Sublimation
Melt
Evaporation
Infiltration
Surface Runoff
Snow
Soil Water
Redistribution
Soil Heat Flux
Heat Transfer
Drainage
CLM simulates energy and moisture exchanges between land and atmosphere
Energy exchanges include radiative transfer, turbulent fluxes, and heat storage in soil
These are controlled in part by the hydrologic cycle
CLM has a detailed representation of the hydrologic cycle including: interception of
water by leaves; infiltration and runoff; multi-layer snow accumulation and melt; 10layer soil water; and partitioning of latent heat into evaporation of intercepted water,
soil evaporation, and transpiration
Bonan (2002) Ecological Climatology (Cambridge University Press)
Coupling CLM to WRF
 CLM modules are kept in tact
 Software maintenance easier with single code
 Code will be shared between WRF, CCSM, and offline
CLM implementations
 CLM will operate on distributed-memory
processors geographically collocated with WRF
DM patches
 Unlike coupling to CCSM where CLM is independently
distributed from CAM for load-balancing
Initializing CLM
 Use CLM global datasets for landunits,
PFTs, soil textures, etc. (static data)
 Later use WRF hi-res global vegetation/soil
data
 Interpolate soil temperature, soil moisture,
snow from WRF input to CLM levels
(dynamic data)
Run-time Coupling
 WRF to CLM
 Lowest level atmospheric wind, temperature,
water vapor
 Downward radiation
 Precipitation
Run-time Coupling
 CLM to WRF
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Wind stress
Sensible heat flux
Latent heat flux and water vapor flux
Albedo
Surface (skin) temperature (upward longwave)
2m T and q
current
WRF-CLM Coupling
Initialization
CLM
preprocessor
Lat/long,
land mask
Land-surface map
Run
WRF SI
Initial atmospheric
state
WRF
Lowest level
height, wind
components,
theta, water
vapor, pressure,
temperature.
WRF
Wind stress,
sensible and
latent heat flux,
water vapor
flux.
Downward
longwave,
shortwave flux.
Declination angle
Skin temp, albedo
2m T and q.
Precipitation
(rain/snow)
CLM
CLM
Initial land state
(arbitrary)
Skin temp,
albedo
planned
WRF-CLM Coupling
Initialization
Run
WRF SI
Soil T,q
interpolated
vertically in
REAL
Landuse/soil, etc.
mapped to grid
WRF
Initial atmospheric
state
Lowest level
height, wind
components,
theta, water
vapor, pressure,
temperature.
WRF
Wind stress,
sensible and
latent heat flux,
water vapor
flux.
Downward
longwave,
shortwave flux.
Declination angle
Skin temp, albedo
Initial land state: Snow,
Soil temp, soil moisture,
canopy water
2m T and q.
Precipitation
(rain/snow)
CLM
CLM
Skin temp,
albedo,
emissivity
Soil temp, soil
moisture,
canopy water,
snow, snow
depth, runoffs,
ground flux (for
WRF output)
Conclusion
 So far we have done tests with fixed initial landstate
 Work is ongoing to provide real initial state to
CLM
 Work is planned to provide WRF hi-res USGS
landuse and FAO soil to initialize CLM landunits
and PFTs
 CLM3 coupled to WRF will be released to the
WRF community when this work is completed