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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




                          August 9, 2004
                 Overview
• Introduction
  – Motivation
  – Lake-ICE
• Simulation Set Up/Results
• Simulation Validation
• Conclusions




                  August 9, 2004
                    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
                            August 9, 2004
                       Lake-ICE
• Lake-Induced Convection Experiment
  (Kristovich, 2000)
• Winter 1997-1998
• UW-Volume Imaging Lidar (UW-VIL)
  located at Sheboygan Point, Wisconsin




                          August 9, 2004
December 21, 1997



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           August 9, 2004
December 21, 1997



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         August 9, 2004
                  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



                      August 9, 2004
                    Simulation Set Up
Grid   Horizontal Points   Vertical Points      Horizontal      Horizontal Size
                                               Resolution (m)        (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




                                  August 9, 2004
Simulation Results




      August 9, 2004
Simulated Backscatter
   •Based  upon passive tracer concentration and
   relative humidity (Mayor, 2003)
   •RH vs. Scattering data from Fitzgerald (1982)




            August 9, 2004
Simulated Backscatter



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             August 9, 2004
Validation




  August 9, 2004
Validation




  August 9, 2004
Validation




  August 9, 2004
Validation




  August 9, 2004
Validation




  August 9, 2004
Validation




  August 9, 2004
Validation




  August 9, 2004
                         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.



                              August 9, 2004
     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

                                     August 9, 2004
               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




                       August 9, 2004
VIL Schematic/Specs




       August 9, 2004

				
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posted:6/14/2011
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