![Page 1: Atmospheric Modeling in an Arctic System Model John J. Cassano Cooperative Institute for Research in Environmental Sciences and Department of Atmospheric](https://reader030.vdocument.in/reader030/viewer/2022032605/56649e7f5503460f94b82e30/html5/thumbnails/1.jpg)
Atmospheric Modeling in an Arctic System Model
John J. Cassano
Cooperative Institute for Research in Environmental Sciences
and Department of Atmospheric and Oceanic Sciences
University of Colorado
![Page 2: Atmospheric Modeling in an Arctic System Model John J. Cassano Cooperative Institute for Research in Environmental Sciences and Department of Atmospheric](https://reader030.vdocument.in/reader030/viewer/2022032605/56649e7f5503460f94b82e30/html5/thumbnails/2.jpg)
Proposed Arctic System Model Domain
![Page 3: Atmospheric Modeling in an Arctic System Model John J. Cassano Cooperative Institute for Research in Environmental Sciences and Department of Atmospheric](https://reader030.vdocument.in/reader030/viewer/2022032605/56649e7f5503460f94b82e30/html5/thumbnails/3.jpg)
Why develop an ASM?
• The Arctic is a unique region that presents unique challenges for climate modeling– An Arctic specific model can use model components that are developed
specifically for polar regions and polar processes • Polar clouds and radiative fluxes• Boundary layer and surface flux processes
• Existing regional Arctic climate models do not account for important feedbacks between Arctic climate system components– Current regional Arctic models simulate atmospheric state but have
specified ocean and ice properties
• Arctic regional models are not subject to low latitude errors present in global climate models– Simulations with an ASM can use “perfect” lateral boundary conditions– Can explore polar processes without feedbacks to lower latitudes
![Page 4: Atmospheric Modeling in an Arctic System Model John J. Cassano Cooperative Institute for Research in Environmental Sciences and Department of Atmospheric](https://reader030.vdocument.in/reader030/viewer/2022032605/56649e7f5503460f94b82e30/html5/thumbnails/4.jpg)
Why develop an ASM?
• Increased horizontal resolution compared to global climate models– Approx. 1 order of magnitude increase in horizontal
resolution compared to global models– Increased horizontal resolution allows for:
• Improved representation of topography and coastlines• Improved representation of small-scale processes
– Extreme events and storms
• More realistic representation of interactions and feedback processes among climate model components
• Better match between model resolution and:– end user needs (e.g. policy decisions)– resolution of other climate system component models– field studies
![Page 5: Atmospheric Modeling in an Arctic System Model John J. Cassano Cooperative Institute for Research in Environmental Sciences and Department of Atmospheric](https://reader030.vdocument.in/reader030/viewer/2022032605/56649e7f5503460f94b82e30/html5/thumbnails/5.jpg)
What Scientific Questions can be Addressed with an ASM?
• Feedback studies– Atmosphere / land hydrology
• Changes in permafrost, soil hydrology, and atmospheric circulation– How will degrading permafrost alter near surface soil moisture?– What impact will changes in soil moisture have on the atmosphere?– Will altered atmospheric state intensify or dampen initial soil moisture
changes due to permafrost degradation?
• Impact of extreme storm events on land hydrology
– Atmosphere / ice / ocean• Role of small scale processes such as polar lows
– How does ice / ocean state impact polar low development?– How do polar lows alter the ice / ocean system?– Do these small scale processes impact larger scales?
![Page 6: Atmospheric Modeling in an Arctic System Model John J. Cassano Cooperative Institute for Research in Environmental Sciences and Department of Atmospheric](https://reader030.vdocument.in/reader030/viewer/2022032605/56649e7f5503460f94b82e30/html5/thumbnails/6.jpg)
What Scientific Questions can be Addressed with an ASM?
• How do high-resolution simulations of the Arctic climate system differ from global climate model simulations?– Consider observed changes in Arctic sea ice
• How do ASM simulations differ from GCSM simulations?• Are different feedback processes acting in the ASM and GCSM?
• What is the role of lower latitude variability vs internal Arctic system processes on observed Arctic change?– Experiments using lateral boundary forcing from multiple GCSMs
and from global reanalyses
![Page 7: Atmospheric Modeling in an Arctic System Model John J. Cassano Cooperative Institute for Research in Environmental Sciences and Department of Atmospheric](https://reader030.vdocument.in/reader030/viewer/2022032605/56649e7f5503460f94b82e30/html5/thumbnails/7.jpg)
Atmospheric Model Requirements
• Community model with active research and development
• Suitable for high resolution (O 1-10 km) simulations
• Capable of long duration climate simulations• Model capable of being run on many different
computer platforms• Optimized for polar applications
![Page 8: Atmospheric Modeling in an Arctic System Model John J. Cassano Cooperative Institute for Research in Environmental Sciences and Department of Atmospheric](https://reader030.vdocument.in/reader030/viewer/2022032605/56649e7f5503460f94b82e30/html5/thumbnails/8.jpg)
ASM Atmospheric Model: WRF
• Suitable for high resolution (O 1-10 km) simulations – Fully compressible, nonhydrostatic dynamics– Significantly improved numerics and dynamics
compared to MM5– Designed for high-resolution applications
• Large eddy simulation• Cloud resolving model• Mesoscale applications
![Page 9: Atmospheric Modeling in an Arctic System Model John J. Cassano Cooperative Institute for Research in Environmental Sciences and Department of Atmospheric](https://reader030.vdocument.in/reader030/viewer/2022032605/56649e7f5503460f94b82e30/html5/thumbnails/9.jpg)
ASM Atmospheric Model: WRF
• Capable of long duration climate simulations– WRF is formulated for mass and scalar conservation
• No long term drift due to model numerics
– Complete atmospheric physics• Radiation• Surface fluxes and land surface• Planetary boundary layer (PBL)• Cloud microphysics• Cumulus parameterization• Multiple options are available for all physical processes
– WRF - Chem is currently under development• Will allow coupled atmosphere - chemistry simulations
![Page 10: Atmospheric Modeling in an Arctic System Model John J. Cassano Cooperative Institute for Research in Environmental Sciences and Department of Atmospheric](https://reader030.vdocument.in/reader030/viewer/2022032605/56649e7f5503460f94b82e30/html5/thumbnails/10.jpg)
WRF Physics Interactions
From NCAR WRF tutorial
![Page 11: Atmospheric Modeling in an Arctic System Model John J. Cassano Cooperative Institute for Research in Environmental Sciences and Department of Atmospheric](https://reader030.vdocument.in/reader030/viewer/2022032605/56649e7f5503460f94b82e30/html5/thumbnails/11.jpg)
ASM Atmospheric Model: WRF
• Model capable of being run on many different computer platforms – WRF runs on Unix single, OpenMP, and MPI platforms
• IBM• Linux (PGI and Intel compilers)• SGI Origin and Altix• HP / Compaq / DEC• Cray• Sun• Mac (xlf compiler)
![Page 12: Atmospheric Modeling in an Arctic System Model John J. Cassano Cooperative Institute for Research in Environmental Sciences and Department of Atmospheric](https://reader030.vdocument.in/reader030/viewer/2022032605/56649e7f5503460f94b82e30/html5/thumbnails/12.jpg)
ASM Atmospheric Model: WRF
• Optimized for polar applications– Prior atmospheric model development effort led to the widely
used Polar MM5• Focus on:
– Cloud and radiation processes– PBL and surface fluxes – Treatment of ice covered land– Sea ice
– On-going development of Polar WRF• Cassano research group at CU• Polar Meteorology Group - BPRC / OSU• NOAA ESRL - Boulder• NCAR - AMPS
![Page 13: Atmospheric Modeling in an Arctic System Model John J. Cassano Cooperative Institute for Research in Environmental Sciences and Department of Atmospheric](https://reader030.vdocument.in/reader030/viewer/2022032605/56649e7f5503460f94b82e30/html5/thumbnails/13.jpg)
Fairbanks - July 2006
WRF - RRTM
Bias: -0.1 mb
Corr: 0.98
WRF - CAM
Bias: 0.8 mb
Corr: 0.98
![Page 14: Atmospheric Modeling in an Arctic System Model John J. Cassano Cooperative Institute for Research in Environmental Sciences and Department of Atmospheric](https://reader030.vdocument.in/reader030/viewer/2022032605/56649e7f5503460f94b82e30/html5/thumbnails/14.jpg)
Barrow - January 2006
WRF - RRTM
Bias: 10.6 deg
WRF - CAM
Bias: 2.7 deg
![Page 15: Atmospheric Modeling in an Arctic System Model John J. Cassano Cooperative Institute for Research in Environmental Sciences and Department of Atmospheric](https://reader030.vdocument.in/reader030/viewer/2022032605/56649e7f5503460f94b82e30/html5/thumbnails/15.jpg)
SHEBA Site - January 1998
Courtesy of Keith HinesBPRC / OSU
![Page 16: Atmospheric Modeling in an Arctic System Model John J. Cassano Cooperative Institute for Research in Environmental Sciences and Department of Atmospheric](https://reader030.vdocument.in/reader030/viewer/2022032605/56649e7f5503460f94b82e30/html5/thumbnails/16.jpg)
Questions or comments?
![Page 17: Atmospheric Modeling in an Arctic System Model John J. Cassano Cooperative Institute for Research in Environmental Sciences and Department of Atmospheric](https://reader030.vdocument.in/reader030/viewer/2022032605/56649e7f5503460f94b82e30/html5/thumbnails/17.jpg)
![Page 18: Atmospheric Modeling in an Arctic System Model John J. Cassano Cooperative Institute for Research in Environmental Sciences and Department of Atmospheric](https://reader030.vdocument.in/reader030/viewer/2022032605/56649e7f5503460f94b82e30/html5/thumbnails/18.jpg)
WRF Model Details
• Mass basedterrain followingvertical coordinate
From NCAR WRF Tutorial
![Page 19: Atmospheric Modeling in an Arctic System Model John J. Cassano Cooperative Institute for Research in Environmental Sciences and Department of Atmospheric](https://reader030.vdocument.in/reader030/viewer/2022032605/56649e7f5503460f94b82e30/html5/thumbnails/19.jpg)
WRF Model Details
• Uses Arakawa C-grid staggering
From NCAR WRF Tutorial
![Page 20: Atmospheric Modeling in an Arctic System Model John J. Cassano Cooperative Institute for Research in Environmental Sciences and Department of Atmospheric](https://reader030.vdocument.in/reader030/viewer/2022032605/56649e7f5503460f94b82e30/html5/thumbnails/20.jpg)
WRF Model Details
• Lateral boundary conditions– Specified from reanalyses, global, or regional models– Open, symmetric, or periodic for idealized simulations
• Top boundary conditions– Constant pressure– Rayleigh damping– Absorbing upper layer– Gravity wave radiation condition (planned)
• Map projections– Polar stereographic– Lambert conformal– Mercator– Cartesian geometry (idealized only)
![Page 21: Atmospheric Modeling in an Arctic System Model John J. Cassano Cooperative Institute for Research in Environmental Sciences and Department of Atmospheric](https://reader030.vdocument.in/reader030/viewer/2022032605/56649e7f5503460f94b82e30/html5/thumbnails/21.jpg)
WRF Model Details
• 3rd order Runge-Kutte time integration• High-order advection scheme• Mass and scalar conserving numerics• One and two-way nesting options• Four dimensional data assimilation (FDDA)• Model physics
– Radiation– Surface– Planetary boundary layer (PBL)– Cloud microphysics– Cumulus
![Page 22: Atmospheric Modeling in an Arctic System Model John J. Cassano Cooperative Institute for Research in Environmental Sciences and Department of Atmospheric](https://reader030.vdocument.in/reader030/viewer/2022032605/56649e7f5503460f94b82e30/html5/thumbnails/22.jpg)
Radiation
• Provides:– Atmospheric temperature tendency– Surface radiative fluxes (SW and LW)
• Options:– Longwave
• RRTM• CAM3• GFDL
– Shortwave• MM5• Goddard• CAM3• GFDL
![Page 23: Atmospheric Modeling in an Arctic System Model John J. Cassano Cooperative Institute for Research in Environmental Sciences and Department of Atmospheric](https://reader030.vdocument.in/reader030/viewer/2022032605/56649e7f5503460f94b82e30/html5/thumbnails/23.jpg)
From NCAR WRF Tutorial
![Page 24: Atmospheric Modeling in an Arctic System Model John J. Cassano Cooperative Institute for Research in Environmental Sciences and Department of Atmospheric](https://reader030.vdocument.in/reader030/viewer/2022032605/56649e7f5503460f94b82e30/html5/thumbnails/24.jpg)
Surface
• Provides:– Surface turbulent fluxes– Soil temperature and moisture– Snow cover– Sea ice temperature
• Options:– Fluxes: Monin-Obukhov similarity theory– Noah LSM– NCEP Noah LSM– RUC LSM
![Page 25: Atmospheric Modeling in an Arctic System Model John J. Cassano Cooperative Institute for Research in Environmental Sciences and Department of Atmospheric](https://reader030.vdocument.in/reader030/viewer/2022032605/56649e7f5503460f94b82e30/html5/thumbnails/25.jpg)
From NCAR WRF Tutorial
![Page 26: Atmospheric Modeling in an Arctic System Model John J. Cassano Cooperative Institute for Research in Environmental Sciences and Department of Atmospheric](https://reader030.vdocument.in/reader030/viewer/2022032605/56649e7f5503460f94b82e30/html5/thumbnails/26.jpg)
Planetary Boundary Layer
• Provides:– Boundary layer fluxes– Vertical diffusion / mixing
• Options:– YSU PBL– Eta PBL– GFS PBL– MRF PBL
![Page 27: Atmospheric Modeling in an Arctic System Model John J. Cassano Cooperative Institute for Research in Environmental Sciences and Department of Atmospheric](https://reader030.vdocument.in/reader030/viewer/2022032605/56649e7f5503460f94b82e30/html5/thumbnails/27.jpg)
From NCAR WRF Tutorial
![Page 28: Atmospheric Modeling in an Arctic System Model John J. Cassano Cooperative Institute for Research in Environmental Sciences and Department of Atmospheric](https://reader030.vdocument.in/reader030/viewer/2022032605/56649e7f5503460f94b82e30/html5/thumbnails/28.jpg)
Cloud Microphysics
• Provides:– Atmospheric heat and moisture tendencies– Cloud and precipitation amount– Surface rainfall
• Options:– Kessler warm rain– Purdue - Lin– WSM 3-class– WSM 5-class– WSM 6-class– Ferrier (NAM)– Thompson
![Page 29: Atmospheric Modeling in an Arctic System Model John J. Cassano Cooperative Institute for Research in Environmental Sciences and Department of Atmospheric](https://reader030.vdocument.in/reader030/viewer/2022032605/56649e7f5503460f94b82e30/html5/thumbnails/29.jpg)
From NCAR WRF Tutorial
![Page 30: Atmospheric Modeling in an Arctic System Model John J. Cassano Cooperative Institute for Research in Environmental Sciences and Department of Atmospheric](https://reader030.vdocument.in/reader030/viewer/2022032605/56649e7f5503460f94b82e30/html5/thumbnails/30.jpg)
Cumulus
• Provides:– Atmospheric heat and moisture tendencies– Surface rainfall
• Options:– Kain-Fritsch– Betts-Miller-Janjic– Grell-Devenyi Ensemble– Simplified Arakawa Schubert GFS
![Page 31: Atmospheric Modeling in an Arctic System Model John J. Cassano Cooperative Institute for Research in Environmental Sciences and Department of Atmospheric](https://reader030.vdocument.in/reader030/viewer/2022032605/56649e7f5503460f94b82e30/html5/thumbnails/31.jpg)
From NCAR WRF Tutorial