Michael Ek and the EMC Land-Hydrology Team Environmental Modeling Center (EMC)

1. Michael Ek and the EMC Land-Hydrology Team Environmental Modeling Center (EMC) National Centers for Environmental Prediction (NCEP) 5200 Auth Road, Room 207 Suitland, Maryland 20732 USA National Weather Service (NWS) National Oceanic and Atmospheric Administration (NOAA) Surface Evaporation in the Noah Land Model in NCEP Operational Weather and Climate Models(or “Noah Land Model & NLDAS”) NASA-USDA Workshop on “Evapotranspiration: An Essential Observation for Climate Understanding and Efficient Water Management” 5-7 April 2011, Silver Spring, Maryland

2. NCEP-NCAR unified Uncoupled “NLDAS” (drought) Forecast NOAH Land Surface Model Noah Land Model Connections in NOAA’s NWS Model Production Suite Oceans HYCOM WaveWatch III Climate CFS 2-Way Coupled Hurricane GFDL HWRF MOM4 GLDAS 1.7B Obs/Day Satellites 99.9% Dispersion ARL/HYSPLIT Regional NAM WRF NMM (including NARR) Global Forecast System Global Data Assimilation Severe Weather Regional Data Assimilation WRF NMM/ARW Workstation WRF Short-Range Ensemble Forecast North American Ensemble Forecast System WRF: ARW, NMM ETA, RSM Air Quality GFS, Canadian Global Model NAM/CMAQ Rapid Update for Aviation (ARW-based)

3. NCEP-NCAR unified Noah land model • Surface energy (linearized) & water budgets; 4 soil layers. • Forcing: downward radiation, precip., temp., humidity, pressure, wind. • Land states: Tsfc, Tsoil*, soil water* and soil ice, canopy water*, snow depth and snow density. *prognostic • Land data sets: veg. type, green vegetation fraction, soil type, snow-free albedo & maximum snow albedo. • Noah coupled with NCEP models: North American Mesoscale model (NAM; short-range), Global Forecast System (GFS; medium-range), Climate Forecast System (CFS; seasonal), & other NCEP modeling systems (i.e. NLDAS & GLDAS).

4. Atmospheric Energy Budget & Hydrological Cycle • Noah land model closes the surface energy and water budgets, and provides surface boundary conditions to NCEP models. (seasonal storage) Surface EnergyBudget Surface WaterBudget Rn = net radiation =S-S+L-L H = sensible heat flux LE = latent heat flux (ET) G = ground heat flux SPC = snow phase-change heat flux S = change in land-surface water P = precipitation R = runoff E = evapotranspiration • Noah provides, SEB: , L, H, LE, G & SPC; SWB: S, R and E.

5. Surface Latent Heat Flux (Evapotranspiration) Canopy Water Evaporation (LEc) Transpiration (LEt) Bare Soil Evaporation (LEd) canopy water canopy soil • LEc is a function of canopy water % saturation. • LEt uses Penman-Monteith formula, and Jarvis (1976)-Stewart (1988) “big-leaf” canopy conductance. • LEd is a function of near-surface soil % saturation. • LEc, LEt, and LEd: functions of LEp (Penman).

6. Latent Heat Flux over Snow LE (shallow snow) < LE (deep snow) Sublimation (LEsnow) LEsnow = LEp LEsnow = LEp snowpack LEns < LEp LEns = 0 soil Shallow/Patchy SnowSnowcover<1 Deep snow Snowcover=1 • LEns = “non-snow” evaporation (evapotranspiration terms). • 100% snowcover a function of vegetation type, i.e. shallower for grass & crops, deeper for forests. • Soil ice = fct(soil type, soil temp., soil moisture).

7. NCEP Climate Forecast System Reanalysis (CFSR) mm/day JJA average • 31-year Evapotranspiration Climatology: 1979-2009. • Other NCEP coupled modeling systems: NAM, GFS. Courtesy: Rongqian Yang, NCEP/EMC/Land-Hydrology Team

8. North American Land Data Assimilation System (NLDAS) • Motivation: Drought important for a multitude of reasons discussed at this workshop and elsewhere. • NLDAS is a multi-institutional effort: NCEP/EMC, Princeton, NWS OHD, NCEP/CPC, NASA/GSFC/HSB, UW, NIDIS; NOAA/CPO (sponsor) • Multi-model land modeling and data assimilation system… • …run in uncoupled mode driven by atmospheric forcing (using surface meteorology data sets)… • …with “long-term” retrospective and near real-time output of land-surface water and energy budgets.

9. Atmospheric Community Noah NCEP operational land model Mosaic NASA GSFC Hydrology Community SAC NWS operational hydrological model VIC Princeton & U. Washington NLDAS Configuration: Land models • Uncoupled (“offline”) simulations. • Input: atmospheric forcing. • Output: water/energy budgets (surface fluxes, land states)

10. Pressure Wind speed Incoming solar Precipitation Air temperature Downward longwave 12 Feb 2011 Specific humidity NLDAS Configuration: Forcing data • Continental US domain, 1/8th degree resolution. • Common land surface forcing from North American Regional Reanalysis real-time extension (gauge-based observed precipitation, temporally disaggregated with radar/sat. data). • 30-year climatologies (January 1979-present): hourly, 1/8-deg, near real-time, forcing data and model output. Courtesy: Youlong Xia, NCEP/EMC/Land-Hydrology Team

11. Courtesy: Youlong Xia Application of Evaporation Percentile Anomaly Current Day Past Week Past Month

12. 1988 1993 NLDAS example: 1988 drought & 1993 flood Monthly Evaporation Anomalies (mm): NLDAS website Courtesy: Youlong Xia www.emc.ncep.noaa.gov/mmb/nldas

13. OBS VIC Noah Mosaic 1997-2006 Courtesy: Youlong Xia Validation Of Evaporation 1997-1999

14. General assessment Climatology and RMS Courtesy: Kingtse Mo NCEP/CPC • RMS differences for solar and long wave radiation are small (about 30 w/(m*m) for summer) • Gflux has the largest RMS differences. The RMS is as large as the mean but both are small in comparison with radiation terms. • Latent heat has the largest RMS in summer. The RMS is about 25% of the mean • Sensible heat does not compare well. The RMS is about 45% of the mean in summer. • Delta: errors in flux data (net radiation-sensible-latent-gflux) are on average about 20-25 W/(m*m) in summer Flux data (solid line), NLDAS (dashed line) & RMS (open circles) averaged over all time period and all stations. Fluxnet data from Tilden Meyers et al, NOAA/ATDD

15. Courtesy: Kingtse Mo NCEP/CPC Comparison of Latent heat fluxfor selected stations • Comparison between the NLDAS and the Ameriflux data is favorable overall. • Ensemble mean performs better than single land model. • Better vegetation fraction may improve LE since vegetation plays an important role. Fluxnet data from Tilden Meyers et al, NOAA/ATDD

16. Assessment of Transpiration Parameters • gc is canopy conductance, gcmin is minimum canopy conductance and gS, gT, ge, g are solar, air temperature, humidity, and soil moisture availability factors, respectively, all functions of vegetation type. Fluxnet data from Tilden Meyers et al, NOAA/ATDD

17. 6 2 1 2 3 1 3 4 4 5 6 7 7 8 8 5 entrainment positive feedback negative feedback land-surface processes surface layer & ABL radiation Local Land-Atmosphere Interactions above-ABL dryness above-ABL stability cloud cover incoming solar downward longwave precipitation boundary-layer growth wind turbulence relative humidity temperature emitted longwave surface temperature reflected solar albedo + * moisture flux sensible heat flux canopy conductance soil moisture soil heat flux soil temperature +positive feedback for C3 & C4 plants, negative feedback for CAM plants *negative feedback above optimal temperature

18. Summary • Noah land-surface model in coupled (NAM, GFS, CFS) and uncoupled (NLDAS, GLDAS-NASA/LIS) operational NWP and climate systems at NCEP. • NLDAS: - land models: Noah, Mosaic, VIC, SAC. - evaluation/validation (e.g. ET). - transition NLDAS to NCEP operations. - continue to support NCEP/CPC & NIDIS. - initial land conditions for coupled models. - extend domain; leverage GLDAS, under NEMS. • Improve Noah land model (e.g. ET physics), & representation of land-atmosphere interactions in models, including role of ET/soil moisture.