Addition of the CLM3 Land-Surface 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-to-interannual 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)?

• Hydrologic cycle• Carbon and nitrogen cycles• Mineral aerosols• Vegetation dynamics• Land use and land cover change

Research tool is the Community Land Model

• Land model for Community Climate System Model• Partnership among NCAR, universities, and government labs through the CCSM land model working group

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 which they represent meteorological, hydrological, and ecological processes and how they utilize satellite data

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.

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

Ongoing Activities

CLM And WRF: IssuesInclusion 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 …

ScienceAre there common experiments that should be done with CCSM and WRF?Can CLM meet the needs of data assimilation?

Software engineeringSurface datasets for WRF gridsInitial datasetsHow 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 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)

Melt

Transpiration

Canopy Water

Snow

Hydrology

Drainage

Evaporation

Interception

Sublimation

ThroughfallStemflow

Infiltration Surface RunoffEvaporation

Precipitation

Soil Water

Redistribution

Direct Solar

Radiation

Absorbed SolarRadiation

Diff

use

Sol

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Rad

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Long

wav

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Reflected Solar Radiation

Em

itted

Lon

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Rad

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Sen

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lux

Late

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ua0

Momentum FluxWind Speed

Soil Heat Flux

Heat Transfer

Pho

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Biogeophysics

Community Land Model

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; 10-layer 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 Wind stress Sensible heat flux Latent heat flux and water vapor flux Albedo Surface (skin) temperature (upward longwave) 2m T and q

WRF-CLM Coupling

WRF

CLM

WRF SICLM preprocessor

WRF

CLM

Lat/long, land mask

Initialization Run

Land-surface map Initial atmospheric state

Declination angleSkin temp, albedo

Lowest level height, wind components, theta, water vapor, pressure, temperature.

Downward longwave, shortwave flux.

Precipitation (rain/snow)

Skin temp, albedo

Wind stress, sensible and latent heat flux, water vapor flux.

2m T and q.

Initial land state (arbitrary)

current

WRF-CLM Coupling

WRF

CLM

WRF SI

WRF

CLM

Initialization Run

Landuse/soil, etc. mapped to grid

Initial atmospheric state

Declination angle

Initial land state: Snow, Soil temp, soil moisture, canopy water

Skin temp, albedo

Lowest level height, wind components, theta, water vapor, pressure, temperature.

Downward longwave, shortwave flux.

Precipitation (rain/snow)

Skin temp, albedo, emissivity

Wind stress, sensible and latent heat flux, water vapor flux.

2m T and q.

Soil temp, soil moisture, canopy water, snow, snow depth, runoffs, ground flux (for WRF output)

planned

Soil T,q interpolated vertically in REAL

Conclusion So far we have done tests with fixed initial land-

state 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