Development of the Regional Arctic Climate System Model RACM

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Development of the Regional Arctic Climate System
Model (RACM) --- Initial Implementation of VIC
within CCSM System through CPL7 Chunmei Zhu1,
Dennis Lettenmaier1, Juanxiong He2, Tony Craig3,
Gabriele Jost4, Wieslaw Maslowski5 1Department
of Civil and Environmental Engineering, Box
352700, University of Washington, Seattle, WA
98195 2International Arctic Research Center,
Fairbanks, AK 3National Center for Atmospheric
Research 4Texas Advanced Computing Center
5Naval Postgraduate School
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Sensible Heat Comparison
Longwave Radiation
1
Coupling Guideline
Introduction

• As part of the development of a
  state-of-the-art Regional Arctic Climate system
  Model (RACM) including high-resolution
  atmosphere, ocean, sea ice, and land hydrology
  components, we implemented the macroscale
  hydrologic model VIC (Variable Infiltration
  Capacity) within CCSM (Community Climate System
  Model) system through the new coupling
  architecture CPL7. Currently, VIC runs for 5 days
  in the CCSM system in an all data (I)
  configuration at global 4x5 resolution. The
  fields sent to the coupler by VIC model at the
  end of the 5 day run were compared with the
  standard CCSM land model CLM (Community Land
  Model) run in the same configuration. The fields
  produced by VIC agree with CLM in most areas.
  Ongoing work is testing the cam/vic/camdom/cice
  configuration (F), run of VIC in the CCSM system
  in fully coupled mode. We are also
  parrallelizing VIC and implementing the VIC
  stream routing model in RACM.

In CCSM4, the communication process is separated
from the component integration process. All
communication processes are taken over by Cpl7
and the components run by themselves. Our coding
work therefore is mainly focused on replacing CLM
with VIC. Most of the coding doesnt involve Cpl7
directly. Key aspects of the work ? Extract
VIC as run in an existing MM5-VIC coupling system
for interaction with the flux coupler (because
VIC in MM5 is in image mode, i.e., runs at all
space for a given time step). ? Current
versions of VIC dont have the capacity for
parallel operation. ? VIC and the flux coupler
exchange fields hourly (the time step at which
VIC runs). This allows WRF and VIC to run at
different time steps. ? The current VIC
version in MM5 is VIC4.0.4. We plan to update VIC
to a newer version after the coupling finished
CLM
CLM
? The sensible heat difference over South
America is explained by the shortwave radiation
difference (Section 8) and surface skin
temperature in section 7. ? Africa shows
reverse pattern between VIC and CLM, also the
Arctic region has larger area with upward
sensible heat for CLM than VIC. These may be
related to differences in model physics.
VIC
VIC
Longwave radiation patterns are similar to
surface skin temperature (section 7). Spatial
patterns of longwave radiation for VIC and CLM
are quite similar.
7
Surface Skin Temperature
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Future Work
VIC Land Component Fields -gt Atmosphere
Component
land -gt atmosphere state variables
structure!---------------------------------------
-------------type lnd2atm_state_type
real(r8), pointer t_rad() !radiative
temperature (Kelvin) real(r8), pointer
t_ref2m() !2 m height surface air temperature
(Kelvin) real(r8), pointer q_ref2m() !2
m height surface specific humidity (kg/kg)
real(r8), pointer h2osno() !snow water (mm
H2O) real(r8), pointer albd(,)
!(numrad) surface albedo (direct) real(r8),
pointer albi(,) !(numrad) surface
albedo (diffuse)end type lnd2atm_state_type
Testing the cam/vic/camdom/cice configuration
(F). Running VIC in CCSM system in fully coupled
mode.
CLM
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Model Description
Parrellizing VIC land model in CCSM system to
improve computing performance.
Implement VIC routing model into RACM
VIC
!-------------------------------------------------
--- land -gt atmosphere flux variables
structure!---------------------------------------
-------------type lnd2atm_flux_type real(r8),
pointer taux() !wind stress
e-w (kg/m/s2) real(r8), pointer tauy()
!wind stress n-s (kg/m/s2)
real(r8), pointer eflx_lh_tot()
!total latent heat flux (W/m82) to atm
real(r8), pointer eflx_sh_tot()
!total sensible heat flux (W/m2) to atm
real(r8), pointer eflx_lwrad_out()
!emitted infrared (longwave) radiation (W/m2)
real(r8), pointer qflx_evap_tot()
!qflx_evap_soi qflx_evap_veg qflx_tran_veg
real(r8), pointer fsa()
!solar radiation absorbed (total) (W/m2)end
type lnd2atm_flux_type
Rout surface and subsurface runoff into rivers
The spatial pattern of surface skin temperature
sent by VIC CCSM4 are quite similar with CLM
CCSM4.
Summary
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Net Shortwave Radiation

• Macroscale hydrologic model VIC has been
  implemented within CCSM system through CPL7.
• VIC CCSM4 successfully runs 5 days in all data
  (I) configuration at global 4x5 resolution.
• The spatial distribution of state and flux fields
  sent by VIC land model are mostly similar to CLM,
  aside from South America for latent heat flux.
  Net solar radiation values for both models are
  unrealistic over Africa and Eurasia.

Latent Heat Comparison
CLM

• Model features
• multiple vegetation classes in each cell
• energy and water budget closure at each time step
• subgrid infiltration and runoff variability
• non-linear baseflow generation
• critical elements relevant to high latitude
  implementations a snow model, a frozen soil
  algorithm, a lake/wetland model, and a blowing
  snow model.

VIC
VIC
CLM
VIC and CLM exhibit generally similar spatial
patterns globally. The biggest differences are
over eastern South America where VIC produces
much higher latent heat fluxes (about 60 W/M2).
This is likely related to the much higher
shortwave radiation produced in VIC-CCSM in this
region (see section 8).
VIC CCSM shortwave radiation extends much
further into eastern South America and eastern
United States than CLM. Values for both models
are unrealistic over Africa and Eurasia.