Analysis of the Goshen County, Wyoming, tornadic supercell on 5 June 2009 during VORTEX2 using EnKF assimilation of mobile radar observations Jim Marquis, Yvette Richardson, Paul Markowski, David Dowell, Josh Wurman, Karen Kosiba, and Paul Photo by Sean Waugh
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Analysis of the Goshen County, Wyoming, tornadic supercell on 5 June 2009 during VORTEX2 using EnKF assimilation of mobile radar observations Jim Marquis,
Goals of Data Assimilation We want a set of realistically evolving analyses (i.e., We are not using DA to initialize a forecast). Analyze roles that mesocyclone-scale processes play in tornadogenesis, maintenance, and decay: - trajectory analysis, - vorticity, momentum budgets, - complete thermodynamic fields, - mid-upper level features,
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Analysis of the Goshen County, Wyoming, tornadic supercell on 5 June 2009 during
VORTEX2 using EnKF assimilation of mobile radar observations
Jim Marquis, Yvette Richardson, Paul Markowski,
David Dowell,
Josh Wurman, Karen Kosiba, and Paul RobinsonPhoto by Sean Waugh
Goals of EnKF analysis• Increase availability of 3-D kinematic and
thermodynamic data (dual-Doppler and in situ obs are spatially/temporally limited).
Paul MarkowskiCourtesy www.vortex2.org
Goals of Data Assimilation• We want a set of realistically evolving analyses (i.e., We are not using DA to initialize a forecast).
• Analyze roles that mesocyclone-scale processes play in tornadogenesis, maintenance, and decay:
Ultimately important for generation of low-level mesocyclone
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More verification: Does ensemble mean vorticity along parcel trajectories match predicted (i.e., integrated) tendency?
Ens. mean interpolatedto trajectory ∫(𝒕𝒊𝒍𝒕+𝒔𝒕𝒓+𝒃𝒂𝒓𝒐 )𝒅𝒕 ∫(𝒕𝒊𝒍𝒕+𝒔𝒕𝒓 )𝒅𝒕
Lagrangian 3-D vorticity budget for a parcel entering mesocyclone:
z = 200 m
X (km)
Y (k
m)
ρ
Ens. mean interpolatedto trajectory ∫ (𝒕𝒊𝒍𝒕+𝒔𝒕𝒓+𝒃𝒂𝒓𝒐 )𝒅𝒕 ∫(𝒕𝒊𝒍𝒕+𝒔𝒕𝒓 )𝒅𝒕
Lagrangian 3-D vorticity budget for a parcel in the forward flank:
X (km)
Y (k
m)
Summary: Utility of EnKF analysis • EnKF Kinematic Analyses:
- Compare well with dual-Doppler fields.
- Most trajectories seem believable;though, Lagrangian vorticity budgets have some problems in some areas of the storm.
• EnKF Thermo Analyses: - Mixed success with comparisons to in situ obs.
• Pressure fields seem unusable.
Acknowledgements• The EnKF experiments were performed using NCAR CISL
supercomputing facilities (bluefire) with the Data Assimilation Research Testbed (DART) and WRF-ARW software.
• Thanks to: Glen Romine, Lou Wicker, Chris Snyder, Nancy Collins, Jeff Anderson, Don Burgess, Dan Dawson, Robin Tanamachi, Bruce Lee, Cathy Finley, Altug Aksoy, Fuqing Zhang, and Matt parker for consulting.
• Thanks to all VORTEX2 crew for their dedication while collecting data on 5 June 2009.
• This research is funded by NSF grants: NSF-AGS-0801035, NSF-AGS-0801041. The DOW radars are NSF Lower Atmospheric Observing Facilities supported by NSF-AGS-0734001.
Extras
Surface gust front
ζ
Pressure diagnosed with posterior ensemble mean thermodynamic variables vs. Pressure retrieved from posterior ensemble mean kinematic fields (e.g., Hane and Ray 1985, Majcen et al. 2008):