P1254413654RNMIH

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Land-Surface Modeling Performance At NCEP
Ken Mitchell

NCEP Environmental Modeling Center
WRF Land Working Group Workshop 18 June 03
NCEP Where America's Climate and Weather
Services Begin
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Collaborators
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Papers recently submitted to GCIP Special Issue
of JGR(Show vugraphs and pass out CDs)

• Papers on Coupled Eta/Noah and EDAS
• Ek et al.
• Berbery et al.
• Papers on Uncoupled NLDAS
• NLDAS N. American Land Data Assimilation System
• Mitchell et al. overview paper
• 9 companion papers by NLDAS collaborators

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Systems Using the Noah Land Model

• OPERATIONAL SYSTEMS
• Eta/EDAS NCEP Eta Model and Eta Data
  Assimilation System
• GFS/GDAS NCEP Global Forecast System (older
  version of Noah)
• AGRMET Air Force Agricultural Meteorological
  Model (USDA)
• DEMONSTRATION TESTBED SYSTEMS
• Eta-RCM Eta Regional Climate Model, 2-4 month
  seasonal fore
• Eta R/R Eta-based Regional Reanalysis (underway,
  1979-2003)
• GFS NCEP Global Model (most current Noah
  version)
• NLDAS Realtime N. American Land Data
  Assimilation System
• NLDAS Retrospective 50-year by CPC (for drought
  monitoring)
• GLDAS NASA/NCEP Global Land Data Assimilation
  System
• MM5/Noah at NCAR
• WRF/Noah at NCAR and NCEP
• ARPS/Noah at Center for Analysis Prediction of
  Storms (CAPS)

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Improving the NCEP MesoscaleEta Model via
Land-Surface Initiatives

• Eta improvement goals
• - 2 meter air temperature and humidity
• - 10 meter wind vector
• - PBL T and Td profiles
• - convective stability indices
• - integrated moisture flux convergence
• - precipitation and cloud cover

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Interannual variability of North American Monsoon
- interior Southwest
July 2001
July 1999
July 2000
semi-dry
Semi-dry soil in Eta
Moist soil in Eta
Dry soil in Eta
obs
32 C
obs
Eta
Eta
Eta forecast hour
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ETA MODEL LAND-SURFACE MODELING MILESTONES
Since 1996, a series of GCIP/GAPP-sponsored
land-surface model related advances have been
made to the NCEP mesoscale Eta model and its
Eta-based 4-D data assimilation system
(EDAS). 31 Jan 1996 multi-layer
soil/vegetation/snow model introduced initial
soil moisture/temperature from GDAS 18 Feb
1997 new vegetation greenness database from
NESDIS refined adjustment of initial GDAS soil
moisture refined evaporation over snow and bare
soil 09 Feb 1998 increase from 2 to 4 soil layers
(10, 30, 60, 100 cm layers) 03 Jun 1998 full
self-cycling of EDAS/Eta soil moisture and
temperature new NESDIS daily 23-km snow cover
and sea ice 15 Mar 1999 "NOAH" name designated
for Eta land-surface model 01 Apr 1999 GOES vs
Eta skin temperature verification 24 Mar 2000 Eta
near-surface regional Forecast Verification
System 15 Mar 2001 retrospective NOAH LSM
Eta/EDAS testing initiated 24 Apr 2001 realtime
NOAH LSM Eta/EDAS testing initiated 02 July
2001 pre-implementation NOAH LSM testing in
parallel Eta/EDAS 24 July 2001 frozen soil
physics, patchy snowcover (OHD, V. Koren) 12 Feb
2002 improved sub-surface heat flux with snowpack
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ETA/NOAH LAND-SURFACE MODEL UPGRADES 24 Jul 01

• - assimilation of hourly precipitation
• -- hourly 4-km radar/gage analysis (Stage V)
• cold season processes(Koren et al 1999) --
  patchy snow cover -- frozen soil (new state
  variable) -- snow density (new state variable)
  
• - bare soil evaporation refinements
• -- parameterize upper sfc crust cap on evap
• - soil heat flux -- new soil thermal
  conductivity
• (Peters-Lidard et al 1998) -- under
  snowpack (Lunardini, 1981) -- vegetation
  reduction of thermal cond. (Peters-Lidard et
  al 1997)
• - surface characterization -- maximum snow
  albedo database
• (Robinson Kukla 1985) -- dynamic thermal
  roughness length
• refinements
• - vegetation
• -- deeper rooting depth in forests
• -- canopy resistance refinements

NOAH LSM tested in various land-model
intercomparison projects, e.g., GSWP, PILPS 2a,
2c, 2d, 2e, Rhone, and (near-future) DMIP.
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July 2001 NOAH LSM improvements in coupled Eta
model Successfully Targeted Impacts 1 - Cold
season processes (snow melt, frozen soil)
reduce near-surface cool bias over snow cover
2 -
Early spring wet soils (soil heat flux, bare soil
evaporation) reduce near-surface moist
bias 3 - Summer over non-sparse green
vegetation reduce near-surface warm bias
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OLD 2-meter Tgt Tdgt
NEW 2-meter Tgt Tdgt
Champaign, Illinois
36-hr
Old model formulation - cool, moist bias in 2-m
T, Td New model formulation reduced cool,
moist bias Physics change new soil thermal
conductivity, nonlinear vs linear dependence of
direct evap on top layer soil moisture
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REDUCING SURFACE MOIST-COOL BIAS OVER WET-BARE
GROUND
00Z lowest boundary-layer level ( 100-150 m)
dew point temperature 48-km parallel new
formulation (NOAH LSM)
00Z lowest boundary-layer level ( 100-150 m)
dew point temperature 48-km parallel old
formulation
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REDUCING NEAR-SURFACE MOIST-COOL BIAS OVER
WET-BARE GROUND IN SPRING
old NOAH LSM
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USA northern mid-west
new NOAH LSM
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2-m relative humidity ()
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obs
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Eta forecast hour
Improved 2-m RH in 48-hour diurnal forecast cycle
during Apr-May
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Shallow/retreating snow cover in USA northern
plain states
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warm advection/melting snowpack case 00Z 02 FEB
2001, 60-hr model run

• old model formulation (upper left)
• gt bulk of incoming energy melts/sublimates snow
  gt skin temp held at freezing
• gt 2-m air temp held near freezing
• new model formulation (upper right)
• gt patchy snow cover for snow depth less than
  threshold depth (veg-type dependent) gt reduces
  surface albedo gt more available energy at sfc
• gt skin temp can exceed 0 C gt 2-m air temp rises
  further above freezing.

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REDUCING SURFACE COOL BIAS OVER MELTING SNOW 02
FEB 2001 warm advection/melting snowpack case
18Z 2-m air temp, old formulation
18Z 2-m air temp, new formulation
The new formulation has less cold bias in 2-m air
temp than old operational formulation over this
region of shallow melting snowpack. (obsplotted
numbers, modelcolor-shaded contouring North
Platt, Neb. circled)
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Mean diurnal cycle of 2-m air temperature of
observations and Eta model 48-hr forecast from
12Z, averaged over 30-day WINTER period of 01
Feb 01 Mar 2001 at all surface stations over
East U.S. Station OBS solid OPS
Eta/NOAH short dash TEST Eta/NOAH
long dash)
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Temperature (C)
-3
0
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Forecast Hour
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Champaign, Illinois
OLD 2-meter Tgt Tdgt
NEW 2-meter Tgt Tdgt
Solid Line surface station
observation Dashed Line coupled Eta / NOAH
model forecast Physics change ground heat flux
under vegetation, canopy resistance parameters
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Mean diurnal cycle of 2-m air temperature of
observations and Eta model 48-hr forecast from
12Z, averaged over 30-day SUMMER period of 12 Aug
12 Sep 2000 at all surface stations over East
U.S. Station OBS solid OPS Eta/NOAH
short dash TEST Eta/NOAH long dash)
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Temperature (C)
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0
48
Forecast Hour
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2-m Air Temp Bias 48-hr Ops Eta Forecast valid
at 00Z EAST
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JULY 2-m Air Temperature EAST (Monthly mean
diurnal cycle over 48-h fcst Obs solid, model
dashed)
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JULY 2-m Relative Humidity (percent)
EAST (Monthly mean diurnal cycle over 48-h fcst
Obs solid, model dashed)
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N-LDAS Design(The Uncoupled Approach)

• 1. Force models with 4DDA surface meteorology
  (Eta/EDAS), except use actual observed
  precipitation (gage-only daily precip analysis
  disaggregated to hourly by radar product) and
  hourly downward solar insolation (derived from
  GOES satellites).
• 2. Use 4 different land surface models
• NOAH (NOAA/NWS/NCEP)
• MOSAIC (NASA/GSFC)
• VIC (Princeton U./ U. Washington)
• Sacramento (NOAA/OHD)
• 3. Evaluate results with all available
  observations, including soil moisture, soil
  temperature, surface fluxes, satellite skin
  temperature, snow cover and runoff.

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LDAS Run Modes1) Realtime, 2) Retrospective

• REALTIME 15 Apr 1999 to 15 Dec 2001
• -- NCEP realtime forcing
• RETROSPECTIVE 01 Oct 1996 to 30 Sep 99
• -- Mandated largely by spin-up issues
• -- NASA-assembled retrospective forcing
• --- Higgins NCEP/CPC reprocessed precipitation
  forcing
• ---- more gages obs, more QC
• --- Pinker U.Md reprocessed solar insolation
  forcing
• ---- better cloud screening, more QC
• Rutgers University compared the soil moisture,
  soil temperature, surface flux results from the
  retrospective LDAS runs to observations over
  Oklahoma/Kansas for last retro year.

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LDAS Model Mean Annual Evaporation (mm) over Oct
97 Sep 99
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LDAS Model Mean Annual Runoff (mm) over Oct 97
Sep 99
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NLDAS Simulated River System
Upstream area log10(km2)
Travel time to outlet days
River flow direction mask
Large River basins
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East Fork of White River at Columbus, IN
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Mean annual modeled normalized model
runoff bias Oct 97-Sep 99
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Fig. 16 From Robock et al.
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April 1999
July 1999
Fig. 22 SGP ARM/CART Monthly Mean Diurnal Cycle
of Surface Energy Fluxes
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April 1999
July 1999
Fig. 24 Monthly Mean Diurnal Cycle of Surface
Skin Temperature
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July 1998