SMALL SCALE SIMULATION AND LIDAR VALIDATION OF A SHALLOW LAKE MICHIGAN LAND BREEZE

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SMALL SCALE SIMULATION AND LIDAR VALIDATION OF A
SHALLOW LAKE MICHIGAN LAND BREEZE

• GIJS DE BOER(1), GREGORY J. TRIPOLI(1), EDWIN W.
  ELORANTA(2)
• (1) DEPARTMENT OF ATMOSPHERIC AND OCEANIC SCIENCE
• (2) SPACE SCIENCE AND ENGINEERING CENTER
• THE UNIVERSITY OF WISCONSIN - MADISON

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Overview

• Introduction
• Motivation
• Lake-ICE
• Simulation Set Up/Results
• Simulation Validation
• Conclusions

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Introduction

• Two main issues
• Small scale events influenced by large scale
  phenomena
• High resolution simulations typically single
  domain LES (Mayor, 2001 Sha et al., 1997)
• Typically do not represent evolution in large
  scale accurately, and lack large scale influence
  (Agee Gluhovsky, 1999)
• Validation of small scale simulations
• Point measurements
• Good for statistical analysis
• Often insufficient to cover large areas
  simulated
• Need big picture
• Implemented Solutions
• Nested simulation covering larger spectrum of
  scales
• Scanning lidar measurements of the atmospheric
  boundary layer for validation purposes

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Lake-ICE

• Lake-Induced Convection Experiment (Kristovich,
  2000)
• Winter 1997-1998
• UW-Volume Imaging Lidar (UW-VIL) located at
  Sheboygan Point, Wisconsin

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December 21, 1997
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December 21, 1997
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UW-NMS

• University of Wisconsin Non-Hydrostatic Modeling
  System (Tripoli, 1992)
• Important Features
• Scalable Two-Way Grid Nesting
• Variably Stepped Topography
• Initialized from ECMWF analysis
• High resolution (100 m) topographical dataset

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Simulation Set Up
Grid Horizontal Points Vertical Points Horizontal Resolution (m) Horizontal Size (km)
1 65x65 50 60000 3780x3780
2 77x77 50 12000 900x900
3 52x52 50 2400 120x120
4 197x157 50 480 93.6x74.4
5 452x362 50 160 72x57.6
6 502x502 50 32 16x16
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Simulation Results
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Simulated Backscatter

• Based upon passive tracer concentration and
  relative humidity (Mayor, 2003)
• RH vs. Scattering data from Fitzgerald (1982)

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Simulated Backscatter
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Validation
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Validation
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Validation
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Validation
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Validation
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Validation
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Validation
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Conclusions

• The UW-NMS can simulate small-scale boundary
  layer events with respectable accuracy utilizing
  the nesting technique.
• General flow features
• Timing of circulation
• Lidar data is invaluable for comparison with
  small-scale numerical simulation in terms of
  capturing the big picture.
• General nature of flow
• Variance calculations
• Additional comparison techniques should be
  developed in order to complete more accurate
  comparison between lidar and model data.

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References/Acknowledgements
Agee, E., Gluhovsky, A., 1999 LES Model
Sensitivities to Domains, Grids, and Large-Eddy
Timescales. Journal of the Atmospheric Sciences,
56, 599-604. Agee, E., Gluhovsky, A., 1999
Further Aspects of Large Eddy Simulation Model
Statistics and Inconsistencies with Field Data.
Journal of the Atmospheric Sciences, 56,
2948-2950. Fitzgerald, J.W., Hoppel, W.A., 1982
The Size and Scattering Coefficient of Urban
Aerosol Particles at Washington, DC as a Function
of Relative Humidity. Journal of the Atmospheric
Sciences, 39, 1838-1852. Mayor, S.D., Tripoli,
G.J., Eloranta, E.W., 2003 Evaluating
Large-Eddy Simulations Using Volume Imaging Lidar
Data. Monthly Weather Review, 131,
1428-1452. Mayor, S.D., 2001 Volume Imaging
Lidar Observations and Large-Eddy Simulations of
Convective Internal Boundary Layers. PhD Thesis
University of Wisconsin - Madison. Tripoli,
G.J., 1992 A Nonhydrostatic Mesoscale Model
Designed to Simulate Scale Interaction. Monthly
Weather Review, 120, 1342-1359. Sha, W.,
Kawamura. T., and Ueda, H., 1991 A Numerical
Study on Sea/Land Breezes as a Gravity Current
Kelvin-Helmholtz Billows and Inland Penetration
of the Sea-Breeze Front. Journal of the
Atmospheric Sciences, 48, 1649-1665. This work
was completed under the following grants NSF
ATM9707165 ARO DAAH-04-94-G-0195
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Model Specifics

• Arakawa C grid
• Tremback/Kessler soil model surface energy budget
  parameterization
• 1.5 level TKE predicting turbulence scheme
• Deardorf vertical scale length
• Vertical scale length used for horizontal as well
  
• Convection parameterization in large domain only
• Full microphysics

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VIL Schematic/Specs
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