Initial Results from the Diurnal Land/Atmosphere
Coupling Experiment (DICE)
Weizhong Zheng, Michael Ek, Ruiyu Sun, Jongil Han, Jiarui Dong and Helin Wei
NOAA/NCEP/EMC, College Park, MD 20740, USA
DICE Workshop
UK Met Office, Exeter, 14-16 October 2013
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OBJECTIVES

DICE Objective: Make an assessment of the impact
of land-atmosphere feedbacks by first assessing the
land and single-column atmosphere models separately,
constrained by observational data, and then
identifying changes due to coupling (DICE Project,
2013).

Examine the performance of NCEP SCM (GFS) and
Noah land surface model with the DICE data set.
(1) OBS ==> Noah or SCM (Stage 1a and 1b)
(2) SCM and Noah coupled to include the land/atmos feedbacks (Stage 2)
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NCEP SCM (GFS)
NCEP GFS: Global Forecast System
Resolution:
T-574 (1760x880) / T190 (576x288)
Vertical levels: 64 (~22m for the lowest model level)
Time step: 7.5 min
PBL scheme: MRF PBL (Troen and Mahrt, 1986; Hong and Pan, 1996)
Land surface processes: Noah V2.7 (Michael Ek et al., 2003)
Radiation scheme:
LW—Rapid Radiative Transfer Model (AER, Mlawer et al. 1997)
SW-- Rapid Radiative Transfer Model version 2 (AER).
Convection scheme: Deep convection and shallow convection
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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). From Mike Ek
Noah Setup
Some related parameters setup in the Noah
Veg type: 12 (Cultivations, SiB-1 veg. class categories)
Soil type:
2 (Silty clay loam, Zobler soil class categoreis)
Albedo:
0.211
GVF:
0.39
Emissivity: 1.0
Z0:
0.3951 (m)
Rsmin:
40
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DICE: Diurnal land/atmosphere coupling experiment
--- Noah off-line run
Model: Noah v2.7
Case: CASES-99 field experiment in Kansas;
3 days: 19UTC Oct. 23 – 19 UTC Oct. 26, 1999
First Stage:
EXP: Noah_Offline
OBS => Noah
Obs atmos forcing ==> Noah
3 days: 19UTC Oct. 23 – 19 UTC Oct. 26, 1999
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Comparison of surface fluxes between simulation and observation
Black: Observation
Red : Simulation (OBS ==>Noah)
Too large latent heat flux
simulated by Noah during
daytime, compared with the
observation.
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Comparison of surface momentum fluxes (u- and v-component)
Black: Observation
Red : Simulation (OBS ==>Noah)
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Comparison of upward SW and LW at the surface
Black: Observation
Red : Simulation (Obs ==> Noah) ( albedo=0.211; emissivity=1.0 )
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Comparison of Tskin between simulation and observation
The surface skin temperature
simulated by Noah is about 5-7
degrees
lower
than
the
observation during daytime.
Black: Observation
Red : Simulation (OBS ==>Noah)
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DICE: Diurnal land/atmosphere coupling experiment
--- SCM (GFS) with Noah
Models: SCM (GFS v2010) (Noah v2.7) (Ruiyu Sun, PBL team)
Case: CASES-99 field experiment in Kansas;
3 days: 19UTC Oct. 23 – 19 UTC Oct. 26, 1999
First Stage:
EXP:
SCM_Obs ;
OBS => SCM
Obs sfc fluxes & Large-scale atmos forcing ==> SCM
Second Stage:
EXP: SCM_Noah
SCM coupled with Noah including the land/atmos feedbacks.
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Large atmospheric forcing for SCM provided by the DICE data set
Horizontal advection heat rate
Horizontal advection moisture change
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Large atmospheric forcing for SCM provided by the DICE data set
Horizontal advection u-comp change
Horizontal advection v-comp change
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Comparison of simulated temperature profiles
SCM_Obs:
SCM driven by observed sfc fluxes & large-scale atmos forcing
SCM_Noah: SCM coupled with Noah including the land/atmos feedbacks.
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Comparison of simulated specific humidity profiles
High simulated moisture near the surface
SCM_Obs:
SCM driven by observed sfc fluxes & large-scale atmos forcing
SCM_Noah: SCM coupled with Noah including the land/atmos feedbacks.
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Comparison of simulated u-component profiles
SCM_Obs:
SCM driven by observed sfc fluxes & large-scale atmos forcing
SCM_Noah: SCM coupled with Noah including the land/atmos feedbacks.
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Comparison of simulated v-component profiles
SCM_Obs:
SCM driven by observed sfc fluxes & large-scale atmos forcing
SCM_Noah: SCM coupled with Noah including the land/atmos feedbacks.
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Comparison of vertical diffusion heat rates
SCM_Obs:
SCM driven by observed sfc fluxes & large-scale atmos forcing
SCM_Noah: SCM coupled with Noah including the land/atmos feedbacks.
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Comparison of vertical diffusion moisture change rates
SCM_Obs:
SCM driven by observed sfc fluxes & large-scale atmos forcing
SCM_Noah: SCM coupled with Noah including the land/atmos feedbacks.
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Comparison of vertical diffusion du/dt
SCM_Obs:
SCM driven by observed sfc fluxes & large-scale atmos forcing
SCM_Noah: SCM coupled with Noah including the land/atmos feedbacks.
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Comparison of vertical diffusion dv/dt
SCM_Obs:
SCM driven by observed sfc fluxes & large-scale atmos forcing
SCM_Noah: SCM coupled with Noah including the land/atmos feedbacks.
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Comparison of simulated PBL height
High PBL height ?
SCM_Obs:
SCM driven by observed sfc fluxes & large-scale atmos forcing
SCM_Noah: SCM coupled with Noah including the land/atmos feedbacks.
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Comparison of surface fluxes between simulation and observation
Black: Observation
Red : Simulation from SCM_Noah
Too large latent heat flux
simulated by Noah during
daytime, compared with the
observation.
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Comparison of surface momentum fluxes
Black: Observation
Red : Simulation from SCM_Noah
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Comparison of upward SW and LW at the surface
Black: Observation
Red : Simulation from SCM_Noah
Lower upward LW at the
surface because of lower
simulated skin temperature
during daytime.
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Comparison of surface skin temperatures
Black: Observation
Red : Simulation from SCM_Noah
Tskin from Noah off-line driven by the
observed atmospheric forcing.
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Summary:
The NCEP SCM (GFS) coupled with Noah land surface model was examined with
the DICE data set, and the result shows as follows:
1) The Noah off-line run driven by the observed atmospheric forcing shows that
the Noah model can reasonably capture the surface momentum and sensible heat
fluxes but substantially overestimate the latent heat flux and underestimate the
surface skin temperature during daytime;
2) The SCM coupled with Noah run shows that the higher moisture near the
surface because of higher latent heat flux, compared with the SCM run driven by
observed surface fluxes and large-scale atmospheric forcing
Future:
(a) Ensemble runs:
- Use set of sfc fluxes derived by other LSMs to drive NCEP SCM;
- Use set of atmos derived by other SCMs to drive Noah.
(b) Investigate parameterization schemes related to the surface fluxes in NCEP
SCM and Noah land surface model as well as their coupling.
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Thank you!
Questions?
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