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RUC Land Surface Model implementation in WRF

Tanya Smirnova, WRFLSM Workshop, 18 June 2003

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Part 1: Current and Future Initialization of

WRF Land States at FSL

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Goal for use of WRF in the Rapid Update Cycle

• 2006 - Use WRF model in Rapid Update Cycle (or Rapid Refresh) application at NCEP

• First step – test WRF model against current RUC hydrostatic model using common RUC initial conditions

WRFRUC – WRF initialized with RUC-20 initial conditions, full-resolution native coordinate data, including 3-d hydrometeor, land-sfc data

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• NCAR mass-coordinate dynamic core - v.1.2.1 • 35 vertical sigma-p levels• Initial conditions including land states for WRFRUC

- native coordinate data from FSL RUC20 cycle including assimilation of observations not yet used in

NCEP operational RUC20 – Coupled Data Assimilation System (CDAS) – available for outside users from

the FSL ftp site in GRIB format

• Lateral boundary conditions from the same FSL RUC20 48h forecast • RUC post-processing adapted to WRF output to produce RUC look-alike GRIB output

WRFRUC model configuration

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RUC CDAS - four-dimensional system (funded by GAPP)

• Uses a forward full-physics model• Cycles surface/soil fields depending on the RUC atmospheric

forcing • Cycles 5 hydrometor species : cloud, ice, rain, snow and

graupel. Cloud clearing/building based on GOES data

New compared to RUC operational –1. Forecast length (48-hour forecasts with hourly outputs)

2. Assimilation of:• NEXRAD Radar reflectivity observations• GPS precipitable water• Boundary-layer profilers• Mesonet observations collected at FS

Main Goal: to improve 1-h precipitation forcing and the land surface model climate

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24-hour precipitation accumulationending at 1200 UTC 6 May 2003

RUC Control

RUC CDAS

Stage IV Rainfall

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Spatial Correlation fields of 24-h Accumulated Precipitation ending at 1200 UTC 6 May 2003

(Dongsoo Kim)RUC CDAS

RUC Control

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Western US

Diurnal cycle of biases from RUC control and RUC CDAS averaged for the period 1 December – 1 March 2003

2-m dew point

2-m temperature

Western US

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Two WRFRUC systems run at FSL in real time:

1. WRFRUC with 10-km horizontal resolution for the TAQ (Temperature and Air Quality) project- 48-hour forecasts twice a day (00 and 12 UTC, runs on JET since June 2002)

2. WRFRUC with 20-km horizontal resolution onCONUS domain- 24-hour forecasts twice a day (00 and 12 UTC, runs on JET since February 2003)

http://ruc.fsl.noaa.gov - real-time fields

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Physics options used in WRFRUC at FSL:

- NCEP 5-class microphysics scheme (option 4)

- RRTM longwave radiation (option 1)

- Dudhia shortwave radiation (option 1)

- Mellor-Yamada-Janjic Monin-Obukhov surface layer (option 2)

- RUC land-surface model (option 3)

- Mellor-Yamada-Janjic TKE scheme (option 2)

- Kain-Fritsch (for CONUS) and Betts-Miller - Janjic (for TAQ) cumulus parameterization

(option 1, 2) as of May 2003

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Schematic presentation of processes included into RUC-LSM

6 levels in soil – 0, 5, 20, 40, 160, 300 cmState variables - volumetric soil moisture, soil temperature,

snow cover/depth/temperature - cycled in RUC 1h cycle since 1997.

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WRFRUC initialization needed:

• Changes to WRF SI (Brent Shaw) –

use of native RUC vertical coordinate rather than isobaric levels to provide initial fields of

atmospheric variables including hydrometeors (vapor, cloud, ice, rain, snow, graupel)

The most recent official release of WRF SI includes all these changes

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REAL changes for WRFRUC initialization :• Changes to REAL (Dave Gill)

• accommodate for level structure in RUC soil domain

• pass through hydrometeor fields

Further changes needed to pass through from SI to WRF model other land-surface related variables such as:• 2 fields for snow temperature • snow density • water vapor mixing ratio at surface• liquid volumetric soil moisture and others

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WRFRUC LSM uses :

- soil and vegetation parameters, vegetation fraction and albedo provided by WRF SI

- cycled soil temperature and moisture from RUC20 (RUC and WRFRUC use the same LSM, land-use and soil classifications, and the same parameter tables)

- cycled snow depth and temperature from RUC20

- ice in soil is initialized in WRF

Atmospheric forcing is provided by WRF. Still need from WRF modeling framework:

- precipitation type (solid versus liquid)- option in surface driver for implicit solution

of energy and moisture budgets

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Vegetation types – both provided by WRF SI(24 USGS classes)

RUC20

WRF10

Land-use parameters:• roughness length• emissivity• plant coefficient

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RUC20

WRF10

Soil types – both provided by WRF SI (16 classes)

Soil parameters –look-up table

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Soil moisture analysisValid 0000 UTC17 June 2003

RUC20

WRF10

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RUC10TerrainElevation(dm)

TAQ domain

RUC20

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Surface temperature 0000 UTC, 17 June 2003

RUC20

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Part 2: Evaluation of LSM performance

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RUC LSM participated in:

Project for the Intercomparison of Land-Surface Parameterization Schemes (PILPS) - Phase 2d

Snow Models Intercomparison Project (SNOWMIP) – Phase 1

RUC LSM is implemented in:

• Operational RUC20 at NCEP

• Real-time RUC20 at FSL (CDAS)

• MM5 chemistry package (Georg Grell) used for

- air quality predictions

- regional climate simulations (FSL, Germany, Israel)

• WRF model

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Improved 1-d (PILPS 2d – Valdai, Russia) total runoff and snow water equivalent forecasts with improved snow and soil physics in MAPS land-surface model

Total runoff

Snow water equivalent

Skin temperature

November 1976 - May 1977

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Effects of frozen soil physics on the simulation of the melting seasons, Valdai, Russia (1966-1983)

Dates when snow ablation starts

Dates when snow pack is all melted

(Smirnova et al., JGR (2000), 105, 4077-4086)

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SNOWMIP, an intercomparison of snow models: first results P. Etchevers, E. Martin, R. Brown et al. ISSW meeting, August 2002

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NESDIS daily snow cover

7 January 2003

8 January 2003

Cycled field of snow depthfrom operational RUC20

at NCEP

Valid at 2100 UTC 8 January 2003

8 January 2003

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WRFRUC12-h forecast

Valid1200 UTC29 January 2003

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WRF-10RUC-10

18-h forecast of surface temperature from RUC and WRFagainst RUC-20 analysis

1800 UTC 29 January 2003

RUC-20

28http://www.etl.noaa.gov/programs/2002/taq/verification

Hartford, CT

9 June 20030000 UTC –11 June 20030000 UTC

Station verificationfor TAQ project

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http://www.etl.noaa.gov/programs/2002/taq/verification

Boston, MA

9 June 20030000 UTC –11 June 20030000 UTC

Station verification

for TAQ project

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http://www.etl.noaa.gov/programs/2002/taq/verification

Worcester, MA

9 June 20030000 UTC –11 June 20030000 UTC

Station verification

for TAQ project

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Variable RUC WRFRUC

Wind spd – s.d. 2.0 2.8

Wind spd bias 0.1 0.9

Temp –s.d. 2.7 2.7

Temp – bias-00z 0.6 -1.2

Dewpoint – s.d. 3.4 3.5

Dewpoint – bias -0.6 -3.2

12-h surface forecasts verified vs. METAR obs11 April – 11 June 2003

RUC-20 vs. WRFRUC-20 – all METARs in domain

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12-h winds aloft forecasts

– verified against rawinsonde

RUC-20 vs. WRFRUC-20

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RUC-20(Grell-Devenyi cumulus)

WRFRUC-20(KF cumulus)

21-h forecasts

Valid 2100 UTC10 June 2003