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Land Component for Arctic System Reanalysis

Land Component for Arctic System Reanalysis. Fei Chen and Michael Barlage Research Applications Laboratory (RAL) The Institute for Integrative and Multidisciplinary Earth Studies (TIIMES) National Center for Atmospheric Research. ASR components. Atmosphere component: WRF-ARW-3dvar

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Land Component for Arctic System Reanalysis

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  1. Land Component for Arctic System Reanalysis Fei Chen and Michael Barlage Research Applications Laboratory (RAL) The Institute for Integrative and Multidisciplinary Earth Studies (TIIMES) National Center for Atmospheric Research Arctic System Reanalysis meeting, NCAR, Boulder,18 January 2008

  2. ASR components • Atmosphere component: WRF-ARW-3dvar • Sea-ice component: Polar WRF sea-ice treatment • Greenland ice-sheet component: Polar WRF land-ice treatment • Land component: Noah and HRLDAS Arctic System Reanalysis meeting, NCAR, Boulder,18 January 2008

  3. Outline • Overview of • Noah land surface model • High-resolution land data assimilation system (HRLDAS) • HRLDAS plan for ASR Arctic System Reanalysis meeting, NCAR, Boulder,18 January 2008

  4. Why Do We Need Land Surface Models in WRF? • Need to account for subgrid-scale fluxes • The lower boundary is the only physical boundary for atmospheric models • LSM becomes increasingly important: • Cloud/cumulus schemes are sensitive to the PBL structures • The PBL growth over land is driven primarily by • Entrainment of warmer air from the free troposphere • Surface sensible and latent fluxes • WRF model increase grid-spacing (1-km and sub 1-km). Need to capture mesoscale circulations forced by surface variability in albedo, soil moisture/temperature, landuse, and snow • Challenge: • Land surface variability and complex land surface/hydrology processes • Initialization of soil moisture/temperature is a challenge Arctic System Reanalysis meeting, NCAR, Boulder,18 January 2008

  5. The Advanced Noah LSM for WRF • Multi-institutional collaborative effort among NCEP, NCAR, U.S. Air Force Weather Agency, NASA, and university community to develop the unified Noah LSM for numerical weather prediction community • Designed for high-resolution realtime weather forecast, air pollution, local and regional hydrologic applications • Noah implemented/tested in • Operational NCEP models: • NAM (12-km, 60-layer) regional model and data assimilation system • GFS global forecast model • GFDL hurricane model • 25-year Regional Reanalysis system (32-km, 60-layer) • Navy: operational COAMPS • Coupled WRF/Noah operational: • AFWA: WRF-ARW for operations July 2006 • NCEP: WRF-NMM for operations June 2006

  6. Noah LSM in WRF V2.2 (Dec 2006) • Improved Physics • Frozen-ground physics • Patchy snow cover, time-varying snow density and snow roughness length • Soil heat flux treatment under snow pack • Modified soil thermal conductivity • Seasonal surface emissivity • Simple treatment of urban landuse • Additional background fields • Monthly global climatology albedo (0.15 degree) • Global maximum snow albedo database • Import various sources of soil initial data • New single-layer urban canopy model Arctic System Reanalysis meeting, NCAR, Boulder,18 January 2008

  7. Noah LSM includes • Land ice (glacier) • Sea ice • The above two will be treated by components in Polar-WRF. • The routines in Noah to deal with these two processes will not be used for ASR • Land-vegetation • Land-bare soil Arctic System Reanalysis meeting, NCAR, Boulder,18 January 2008

  8. 1-km Global Landuse Map determine Rc_min, and other vegetation parameters Arctic System Reanalysis meeting, NCAR, Boulder,18 January 2008

  9. Global Soil Texture Map determine Kt, and other soil parameters Arctic System Reanalysis meeting, NCAR, Boulder,18 January 2008

  10. Seasonality of vegetation Based on monthly NDVI Arctic System Reanalysis meeting, NCAR, Boulder,18 January 2008

  11. WRF/ Noah Snow Storm Case 18 March 2003 24-h snow water equivalent change valid at 00Z 19 March Snow melted too quickly in the previous version Of Noah Obs 24-h SWE change valid at 06Z 19 March Arctic System Reanalysis meeting, NCAR, Boulder,18 January 2008

  12. Frozen-ground physics in Noah improve simulations of soil temperature, soil moisture, and runoff Evaluation using Rosemount Field Experiment Data, Minnesota freezing rain+snow melt thawing Noah (OSU) Noah (OSU) Noah with frozen ground Noah with frozen ground observations observations Details see Koren, Schaake, Mitchell, Duan, Chen, Baker, 1999, JGR

  13. New fix in the Noah Penman equation for snow-covered surface reduce low-level Q bias (WRF 3.0)2m-RH, 18Z, 6 March 2007 Modified Difference (Modif-Orig) Snow cover

  14. Motivation for HRLDAS • Mesoscale models need to capture PBL structures and motions resulted from surface forcing • No routine high-resolution soil observation network • Ultimate approach is to combine observation, modeling, and data assimilation • Alternatives: Using observed rainfall, analyzed downward solar radiation, and atmospheric analysis to drive LSMs in uncoupled mode • NCEP NLDAS: North America, 1/8 degree • AFWA ARGMET: global, 47-km, long-term archive • NCAR High-resolution land data assimilation system (HRLDAS) Arctic System Reanalysis meeting, NCAR, Boulder,18 January 2008

  15. NCAR High-Resolution Land Data Assimilation System (HRLDAS) Concept Run uncoupled LSM on the same grid as mesoscale NWP models • Using the same LSM as in coupled NWP model: same soil moisture climatology • No Mis-match of terrain, land use type, soil texture, physical parameters between sources of soil data and NWP models • No interpolation and soil moisture conversion Arctic System Reanalysis meeting, NCAR, Boulder,18 January 2008

  16. HRLDAS: Capturing Small-Scale VariabilityAn example over CONUS • Input: • 4-km hourly NCEP Stage-II rainfall • 1-km landuse type and soil texture maps • 0.5 degree hourly GOES downward solar radiation • 0.15 degree AVHRR vegetation fraction • T,q, u, v, from model based analysis • Output: long term evolution of multi-layer soil moisture and temperature, surface fluxes, and runoff 4-km HRLDAS surface soil moisture in IHOP-2002 domain 12 Z May 29 2002 Arctic System Reanalysis meeting, NCAR, Boulder,18 January 2008

  17. Spin-up of Soil Moisture (top 10 cm soil) Initial time From coarse resolution of EDAS field 46 days later Heterogeneity was developed in the 4-km domain Arctic System Reanalysis meeting, NCAR, Boulder,18 January 2008

  18. Spin-up of Soil Moisture Volumetric soil moisture RMS difference (m3m-3) 0.02 < 0.1 < 0.02 0.1 1st layer soil moisture 3rd layer soil moisture Coarse soil Medium soil Fine soil Chen et al., J. Appli. Meteorol. Climate, 2007

  19. HRLDAS for ASR • Blending atmospheric and land-surface observations and land surface model • To provide land state variables for driving the coupled WRF/Noah-Polar modeling system • Soil moisture (liquid and solid phase) • Soil temperature • Snow water equivalent and depth • Canopy water content • Vegetation characteristics • To provide long-term evolution of the above variables plus surface hydrological cycle (runoff, evaporation) and energy cycle (surface heat flux, ground heat flux, upward long-wave radiation) Arctic System Reanalysis meeting, NCAR, Boulder,18 January 2008

  20. ASR Land Modeling Timeline HRLDAS Spin-up HRLDAS and WRF coupled simulations 1998 2000 2010 Arctic System Reanalysis meeting, NCAR, Boulder,18 January 2008

  21. ASR Land Modeling Timeline HRLDAS Spin-up Forcing Data 1hr 1hr Hourly Forcing Data GLDAS: T,q,U,p,SW,LW CMAP: precipitation GDAS: SW, LW GOES: SW,LW Air Force: snow 1998 2000 Arctic System Reanalysis meeting, NCAR, Boulder,18 January 2008

  22. ASR Land Modeling Timeline HRLDAS and WRF coupled simulations HRLDAS communicates to WRF 3hr 1hr 1hr 1hr 2000 2010 Blended WRF Input to HRLDAS Blended Hourly Forcing Data WRF: T,q,U,SW,LW CMAP: precipitation GDAS: snow, SW, LW Air Force: snow GLDAS: SW, LW Improved Land Surface States Snow Soil Moisture/Temperature Land Surface Temperature

  23. Comparison of SW radiation inputs Arctic System Reanalysis meeting, NCAR, Boulder,18 January 2008

  24. Satellite data - MODIS & AVHRR • fPAR/LAI: MODIS 8-day, 1km, 2000-current • Albedo: MODIS 8-day, 1km, 2000-current • Land Skin Temperature: MODIS 8-day and daily, 1km and 6km, 2000-current • Green Vegetation Fraction: MODIS-based, 1km, 16-day, 2000-current • Green Vegetation Fraction: AVHRR, weekly, 0.144deg, 1982-2005 Arctic System Reanalysis meeting, NCAR, Boulder,18 January 2008

  25. Improved Surface Spatial Heterogeneity Arctic System Reanalysis meeting, NCAR, Boulder,18 January 2008

  26. 600 x 600 cells • 20 km • polar projection • ref_lat = 90 • ref_lon = 0 • truelat = 70 • stand_lon = -110 WRF domain Arctic System Reanalysis meeting, NCAR, Boulder,18 January 2008

  27. MODIS 1km Vegetation DataJune 18, 2002 Arctic System Reanalysis meeting, NCAR, Boulder,18 January 2008

  28. Vegetation Data: MODIS vs WRFJune 18, 2002 Absolute difference Relative difference

  29. HRLDAS Algorithm Canopy water, Snow, Tskin ,Tsoil, Soil moisture Forcing data: GRIB format SW, LW T,q,ps,U,precip WPS Metgrid Interpolated forcing data: NetCDF format Canopy water, Snow, Tskin,Tsoil, Soil moisture SW, LW T,q,ps,U,precip Merged IC file Merged forcing file Static input WPS Geogrid HRLDAS …. MODIS Arctic System Reanalysis meeting, NCAR, Boulder,18 January 2008

  30. Preliminary HRLDAS Spin-up July 1, 1999 Downward Solar Radiation Incident at the Surface Hourly GLDAS forcing data based on observed clouds and simple 3-layer radiation model Arctic System Reanalysis meeting, NCAR, Boulder,18 January 2008

  31. Preliminary HRLDAS Spin-up July 1999 Surface Skin Temperature Hourly HRLDAS output plotted at 2Z every day for a month Arctic System Reanalysis meeting, NCAR, Boulder,18 January 2008

  32. Preliminary HRLDAS Spin-up July 1999 Soil Moisture 2nd Layer Hourly HRLDAS output plotted at 2Z every day for a month Arctic System Reanalysis meeting, NCAR, Boulder,18 January 2008

  33. Summary • HRLDAS will provide high-resolution on the same grid of WRF-3dvar • land-state variables to drive WRF/Noah for analysis phase • Long-term evolution of surface hydrological and energy budget components • The latest Noah (to be released in March 2008 in WRF 3.0) is used for HRLDAS for ASR • Possible enhancements: Noah model physics and data assimilation • Collection of atmospheric forcing and satellite data for use in HRLDAS is in progress • Need to coordinate with • “atmospheric” team • WRF configuration, duration of reanalysis, hourly WRF output • “evaluation” team • Data collection and verification approach Arctic System Reanalysis meeting, NCAR, Boulder,18 January 2008

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