Summary of Current and Ongoing Cold Pool Modeling ResearchUniversity of Utah/DAQ CAP

John Horel, Erik Crosman, Erik NeemannUniversity of Utah

Department of Atmospheric Sciences

Lance AveyUtah DAQ

AMS Annual Meeting 18th Joint Conference on the Applications of Air

Pollution Meteorology with the A&WMA Atlanta, GA

4 February 2014

Summary of Current Problems Simulating Meteorology of CAPs

Clouds•Type (ice or liquid)•Extent•Duration

Winds•Too strong in surface layer•Over-dispersive, mix-out and end of CAP too soon

Stability profile•Too weak/diffuse of capping inversion•Improper depth of mixed layers

Land surface•Snow cover and albedo evolution often mispecified

Winds

YSU PBL ΔX 1.33 km LES ΔX 0.25 km

LES ΔX 250 m

OBSERVATIONS

COARSE ΔX 1335 m

Stability profile•Too weak/diffuse of capping inversion•Improper depth of mixed layers

Stability

Snow cover

NAM 12Z 1 Dec F000 GJT

Clouds observed

GFS

Summary of Uintah Basin WRF CAP Modifications

• 1. An “idealized” layer of snow and SWE was specified in the WRF initialization fields based on elevation in a manner similar to Alcott and Steenburgh (2013).

• 2. Albedo modified to observations; • 3. WRF vegetation parameter changed to let less snow cover ground• 4. Thompson Microphysics modified to produce more realistic ice clouds; turned off

cloud ice sedimentation and the autoconversion of cloud ice in boundary-layer

• Summary of modifications and cold pool in Uintah Basin modeling resultsIn manuscript about to be submitted:

• Simulations of a cold-air pool associated with elevated wintertime ozone in the Uintah Basin, Utah

• • E. M. Neemann1, E. T. Crosman1, J. D. Horel1, and L. Avey2 • [1]{Department of Atmospheric Sciences, University of Utah, Salt Lake City, Utah}• [2]{Utah Division of Air Quality, Salt Lake City, Utah}

Future CAP Modeling Plans• Further testing to determine best model parameterizations (PBL,

microphysics, land surface) for CAP cases for spectrum of cold pool types• Further edits to cloud microphysics code (e.g., testing WRF ice-fog

scheme of Kim et al. (2014) in Uintah Basin )• Sensitivity to initialization time and initial conditions (starting at

beginning or middle of CAP)• Sensitivity to land use data set (USGS, MODIS, NLCD 2006)• Possible edits to boundary-layer scheme or turn boundary-layer scheme

off (LES) (J. Massey U of U) • Sensitivity to model vertical and horizontal resolution for range of CAP

types• Incorporate snow physics model in addition to better initial snow fields

like what • Hopefully better understanding of what physical processes/aspects of

CAPs that models are struggling with will be gained