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Current and Future Initialization of WRF Land States at NCEP Ken Mitchell NCEP/EMC WRF Land Working Group Workshop 18 June 2003 Initialization Requirements for Unified Noah LSM in NCEP Eta and WRF runs • Prognostic State Variables – – – – Soil moisture (liquid and frozen): 10, 30, 60, 100 cm Soil temperature: 10, 30, 60, 100 cm Snowpack: actual and water-equivalent depth Canopy water content: intercepted precip, dew • Land Surface Characteristics – – – – Soil class Land-use class (e.g vegetation, urban) Vegetation phenology (seasonal cycle of greenness) Vegetation and soil physical parameters LSM Initialization Philosophy at NCEP • Optimum for WRF or Eta models – Eta or WRF model has its own continuously cycled data assimilation system with same LSM physics, soil layers, grid, terrain, land mask, fixed fields of land use and soil class, physical parameters • Coupled (EDAS/GDAS): all land surface forcing from parent atmosphere model (may include precipitation assimilation) • Uncoupled (NLDAS/GLDAS): precipitation and solar insolation forcing are from non-model sources LSM Initialization Philosophy at NCEP • Best alternative when continuous cycling not available – When? WRF or Eta executed on a domain different from cycled WRF or Eta data assimilation system • Ensemble runs as coarser resolution • Ultra high resolution: dispersion modeling • Local meso model runs: field offices, labs, universities – How ? Take land states, land-use map, soil map, parameters from most-similar fully cycled land data assimilation system: • same LSM, same soil layers • Use nearest neighbor interpolation to obtain land states, landuse map, soil class map and apply same parameter tables EDAS: Eta/Noah, 12-km with precip assimilation Pre-forecast data assimilation period Free forecast period In the forecast period between the analysis steps of the 12h pre-forecast data assimilation period, at each time step and at each point where observed precipitation is available, we compare Pmod to Pobs, then modify the model’s temperature, moisture, cloud and rain field to be more consistent with observed precipitation. Interannual variability of North American Monsoon - interior Southwes July 1999 moist 23 16 00 Semi-dry soil in Eta Dry soil in Eta obs 29 C 32 24 Eta 12 semi-dry dry Moist soil in Eta 30 July 2001 July 2000 24 36 obs 33 C Eta Eta forecast hour 16 48 00 12 24 36 48 32 C 32 24 16 00 12 24 36 48 Sources of Noah Land States at NCEP • Coupled cycled LDAS: Realtime – EDAS: 12-km Eta/Noah (4 soil layers: 10, 30, 60, 100 cm) – GDAS: 1-deg GFS/OSU (2 soil layers: 10, 190 cm) • Coupled cycled LDAS: Historical – Global Reanalysis I: 1948- present (GDAS: 2.5 deg) – Global Reanalysis II: 1979-present (GDAS: 2.5 deg) – Regional Reanalysis: 1979-2004 (EDAS: 32-km) • Uncoupled cycled LDAS: Realtime parallels – NLDAS (N. American Land Data Assimilation System) • 1/8-deg, CONUS grid, Noah LSM, 4 layers – GLDAS: Global Land Data Assimilation System • ½-deg, Noah LSM, 4 layers • NASA spearheaded Initializing 8-km WRF/Noah runs at NCEP • Present: From 12-km EDAS – – – – – – WRF uses same Noah LSM as EDAS WRF use same Noah LSM parameter tables Land States from nearest neighbor interpolation Land-class and soil class from nearest neighbor Soil temperature profile adjusted for terrain height differences Frozen soil moisture adjusted if soil temperature adjusted • Future: From 8-km NLDAS executing on WRF grid Expanding LSM-related content in NCEP Eta/EDAS/NLDAS GRIB output • All land states at all soil layers – Total and liquid soil moisture – Actual and physical snow depth • Land use class and soil class • Fundamental vegetation and soil parameter fields • Nearest neighbor interpolation from native grid to chosen output grid LSM Issues for WRF SI • Pass two land-use fields to WRF – Default – From same source as input land states • Pass two soil-class fields to WRF – Default – From same external source as input land states • Pass flag for source of WRF land-use and soil class fields – True=Default, False=External • Pass label indicating source of input land states – e.g. EDAS, AGRMET, NLDAS, RUC, HRLDAS • VTABLE: Multiple GRIB tables employed in GRIB file – NCEP GRIB Tables 2, 129 (cloud micro), 130 (land-related) • VTABLE: How handle new GRIB grid numbers?