Arcto

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Polar WRF
David H. Bromwich and Keith M. Hines Polar
Meteorology Group Byrd Polar Research Center The
Ohio State University Columbus, Ohio
Supported by NSF, NOAA, NASA, and DOE
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WRF -----?Polar WRF
Polar Optimization by BPRC PMG Fractional sea
ice (ice and water within the same grid box) Sea
ice albedo (specify to vary with time and
latitude) Morrison microphysics (2-moment) Noah
LSM modifications Heat transfer for snow and
ice Surface energy balance
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Testing of Polar WRF at OSU

• Permanent ice sheets
• Start with Greenland (Follow Polar MM5 path)
• January 2002 (winter) and June 2001 (summer)
• Hines and Bromwich (2008, MWR, in press)
• Also Antarctic AMPS forecasts (NCAR MMM Division)
• Antarctic climate simulations (Elad Shilo at
  BPRC)
• Polar pack ice
• Use 1997/1998 Surface Heat Budget of the Arctic
  (SHEBA) observations on drifting sea ice
• Selected months January, June, and August
• Bromwich et al. (2009, JGR-Atmospheres, in
  review)
• Arctic land - Underway

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Greenland and Arctic Ocean Studies
Greenland Grid SHEBA-Western
Arctic Grid
97 x 139 24 km spacing 28 levels
141 x 111 25 km spacing 28 levels
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Polar MM5 Correlation 0.93 Bias -2.6 RMSE 3.7
Polar WRF Correlation 0.92 Bias -0.1 RMSE 3.1
Polar MM5 Correlation 0.75 Bias 4.4 RMSE 5.5
Polar WRF Correlation 0.92 Bias 1.2 RMSE 2.8
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Incident Longwave Radiation at Summit Greenland
June 2001
Polar MM5 shows a deficit for incident longwave
radiation. Polar WRF is much improved and shows
a small bias at Summit Greenland
Incident Shortwave Radiation at Summit Greenland
June 2001
Both Polar MM5 and Polar WRF reasonably represent
the diurnal cycle of incident shortwave
radiation.
Local Standard Time
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Agreement between simulated and observed surface
pressure demonstrates that Polar WRF is capturing
the synoptic variability with high skill at Ice
Station SHEBA during January 1998
Correlation 0.98 Bias 0.5 hPa RMSE 2.2
hPa
Similar results are seen for June and August 1998
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Surface Temperature at Ice Station SHEBA
January 1998
Surface Temperature at Ice Station SHEBA June
1998
Surface Temperature at Ice Station SHEBA August
1998
August 1998
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Figure 9 10-m Wind speed (m s-1) from
observations and the Polar WRF simulation at Ice
Station SHEBA for January, June and August 1998
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Impact of open water fraction Consider Ice
Station SHEBA and point (51,59)
Ice fraction
Temperature difference can exceed 15ºC
Pt (51,59)
SHEBA
At Ice Station SHEBA the temperature difference
is very small as open-water fraction is very small
At point (51,59) the temperature difference
becomes very large as open-water fraction becomes
significant
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Summary/What is next?

• Polar WRF works well over the Greenland Ice
  Sheet
• Polar WRF captures synoptic variability
  with high skill over the Arctic pack ice
• small bias
• high-frequency errors due to local clouds
• Test over Arctic land underway
• is there a warm bias during winter?
• snow cover
• initial soil temperature and moisture
• stable boundary layer topography
• Antarctic climate tests
• AMPS Antarctic real-time forecasts
• Arctic System Reanalysis preparations

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Validating WRF for mesoscale Arctic climate
studies Amy Solomon, Ola Persson, Matt
Shupe NOAA/Earth System Research Laboratory,
Boulder, Colorado CIRES/University of Colorado,
Boulder, Colorado Hugh Morrison National Center
for Atmospheric Research, Boulder,
Colorado Jian-Wen Bao NOAA/Earth System
Research Laboratory, Boulder, Colorado
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Focus of NOAA/ESRL Studies
Key Points 1) Process-oriented validation of key
parameterizations of primary benefit a)
extensive parameters, intensive field campaigns
guided by modeling needs b) validation of
parameters at end of complex processes of limited
use 2) Our view of key parameterizations a)
Cloud microphysics (focus maintenance of liquid
water, interactions with aerosols/radiation/dynami
cal forcing) b) Surface schemes (focus
snow/ice model - multi-layer, interactive,
advective, but relatively simple) c) Boundary
layer schemes (focus stable PBL, non-MOS
processes)
3) Our niche-collect process-oriented validation
data and do process-focused modeling - limited
staff for extensive model/parameterization
development - contribute interaction with
model/parameterization development group
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Validation of Cloud Microphysics during M-PACE

• Weather Research Forecast Model V2.2
• Nested 18/6/1 km horizontal grids
• 50 vertical levels (20 levels below 800 hPa).
• Morrison Two-Moment microphysics
• CAM Radiation
• 3D PBL mixing in the 1km grid (YSU in 18/6 km)
• NOAH LSM

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Validation of Water Paths and Surface Radiation
at Barrow, Alaska
LW
SW
Observations 2M Morrison 1M Morrison
IWP
LWP
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Validation of Cloud Droplet, Snow, and Ice Size
Distributions
Aircraft Measurements
Morrison Microphysics
(After MacFarquhar et al. 2007)
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Validation of Liquid and Ice Water Content
Retrievals Morrison Microphysics
IWC LWC
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END
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Impact of Horizontal Resolution at Barrow
1 KM 50 KM
24-hour average
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Development and Evaluation of Polar WRFat the
University of Colorado

• John J. Cassano and Mark W. Seefeldt
• University of Colorado at Boulder
• Cooperative Institute for Research in
  Environmental Sciences
• Department of Atmospheric and Oceanic Sciences

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Arctic System Model

• The efforts at the University of Colorado are in
  preparation for the use of WRF in a regional
  Arctic climate system model
• Atmosphere Ocean Sea ice Land / hydrology
• WRF will be the atmospheric component of the ASM

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Polar WRFInitial Work at the University of
Colorado

• Evaluation of native WRF 3.0 physics
  parameterizations for polar use
• Identify parameterizations that are inappropriate
• Identify a preferred suite of model
  parameterizations
• Identify aspects of model in need of improvement
• Evaluate the atmospheric state
• Evaluate atmospheric processes
• Are we getting the right answer for the right
  reasons?
• Evaluate preferred physics parameterizations
  against Polar MM5

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SHEBA Simulations

• Simulations during SHEBA year
• January and June 1998
• WRF 3.0
• Model forcing
• ECMWF TOGA
• atmospheric data / SST
• ERA40
• sea ice and soil state
• Model grid
• 50 km horizontal
• 31 vertical levels
• Model top 50 mb

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WRF Physics

• There are seven primary physics
  parameterizations
• longwave radiation RRTM, GFDL, CAM
• shortwave rad. Goddard, Dudhia, GFDL, CAM
• boundary layer Yonsei Univ. (YSU),
• Mellor-Yamada-Janjic (MYJ/Eta), ACM2
• surface layer (coupled with boundary layer)
• land surface Noah, RUC, thermal diffusion
• microphysics Morrison, WRF SM5, Thompson,
• five others
• cumulus Kain-Fritsch, Grell-Devenyi, BMJ, two
  others
• Key preferred acceptable - failed

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Shortwave Radiation Goddard and Dudhia
Goddard SW
June 1998
Dudhia SW
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Boundary Layer YSU and MYJ
YSU
January 1998
MYJ
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Land surface Noah LSM and thermal diffusion
January 1998
Noah LSM
Thermal diffusion model
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Conclusions Polar WRF Development

• Some WRF physics options are clearly
  inappropriate for polar applications
• Dudhia SW large negative bias in SWD
• Thermal diffusion soil model large warm bias
• There appear to be issues with other physics
  options, which need more analysis
• Grell-Devenyi cumulus excessive cloud cover
• MYJ PBL wintertime cold bias
• Polar WRF has better skill than PMM5 for Jan
• Polar WRF has similar skill as PMM5 for June
• Processes in Polar WRF appear more realistic than
  in Polar MM5