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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DICE 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)

OBJECTIVESOBJECTIVES

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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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From Mike Ek

NCEP-NCAR unified Noah land model

• 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).

• 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 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: ObservationRed : 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: ObservationRed : Simulation (OBS ==>Noah)

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Comparison of upward SW and LW at the surface

Black: ObservationRed : Simulation (Obs ==> Noah) ( albedo=0.211; emissivity=1.0 )

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Comparison of Tskin between simulation and observation

Black: ObservationRed : Simulation (OBS ==>Noah)

The surface skin temperature simulated by Noah is about 5-7 degrees lower than the observation during daytime.

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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 forcingSCM_Noah: SCM coupled with Noah including the land/atmos feedbacks.

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SCM_Obs: SCM driven by observed sfc fluxes & large-scale atmos forcingSCM_Noah: SCM coupled with Noah including the land/atmos feedbacks.

Comparison of simulated specific humidity profiles

High simulated moisture near the surface

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SCM_Obs: SCM driven by observed sfc fluxes & large-scale atmos forcingSCM_Noah: SCM coupled with Noah including the land/atmos feedbacks.

Comparison of simulated u-component profiles

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SCM_Obs: SCM driven by observed sfc fluxes & large-scale atmos forcingSCM_Noah: SCM coupled with Noah including the land/atmos feedbacks.

Comparison of simulated v-component profiles

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Comparison of vertical diffusion heat rates

SCM_Obs: SCM driven by observed sfc fluxes & large-scale atmos forcingSCM_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 forcingSCM_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 forcingSCM_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 forcingSCM_Noah: SCM coupled with Noah including the land/atmos feedbacks.

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Comparison of simulated PBL height

SCM_Obs: SCM driven by observed sfc fluxes & large-scale atmos forcingSCM_Noah: SCM coupled with Noah including the land/atmos feedbacks.

High PBL height ?

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Comparison of surface fluxes between simulation and observation

Black: ObservationRed : Simulation from SCM_Noah

Too large latent heat flux simulated by Noah during daytime, compared with the observation.

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Black: ObservationRed : Simulation from SCM_Noah

Comparison of surface momentum fluxes

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Black: ObservationRed : Simulation from SCM_Noah

Comparison of upward SW and LW at the surface

Lower upward LW at the surface because of lower simulated skin temperature during daytime.

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Black: ObservationRed : Simulation from SCM_Noah

Comparison of surface skin temperatures

Tskin from Noah off-line driven by the

observed atmospheric forcing.26

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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