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 Simulation Set Up/Results Simulation Validation Motivation Lake-ICE Simulation Set Up/Results Simulation Validation Conclusions August 9, 2004

Introduction Two main issues: Implemented Solutions 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 August 9, 2004

December 21, 1997 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

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