MEASURED TURBULENCE

All measured turbulence values are passed to AERMOD if the hour is non-missing. This is true even for those levels where the wind  speed is below u_TH . 

Based on measurements with research grade instruments, reasonable minimum turbulence levels in non-calm conditions for vertical turbulence (_w ) and lateral turbulence (_v ) w v values are set by AERMOD to 0.02 m/s and 0.2 m/s, respectively.

Although these lower limits are applied to the measured values of the turbulence the calculated profile values of _w &_v are not subjected to any lower limits. We do not w v restrict these estimated profiles because it would bias the calculation of the effective values of turbulence, which are averages through the layer between the receptor and the plume height, in determining the dispersion of the plume.

8 APPENDIX: Input / Output Needs and Data Usage

8.1 AERMET Input Data Needs
      8.1.1 METEOROLOGY 
      8.1.2 DIRECTIONALLY AND/OR MONTHLY VARYING SURFACE
              CHARACTERISTICS 
      8.1.3 OTHER
      8.1.4 OPTIONAL
8.2 Estimation of solar insolation for small solar elevation angles
8.3 Selection and Use of Measured Winds, Temperature and Turbulence in AERMET
      8.3.1 THRESHOLD WIND SPEED 
      8.3.2 REFERENCE TEMPERATURE AND HEIGHT
      8.3.3 REFERENCE WIND SPEED AND HEIGHT 
      8.3.4 CALCULATING THE POTENTIAL TEMPERATURE GRADIENT
              ABOVE THE MIXING HEIGHT FROM SOUNDING DATA
      8.3.5 MEASURED TURBULENCE
      8.3.6 DATA SUBSTITUTION FOR MISSING ON-SITE DATA 
8.4 Information Passed by AERMET to AERMOD
8.5 Restrictions on the Growth of PBL Height 
8.6 Initializing the Mechanical Mixing Height Smoothing Procedure
8.7 Determining The Mixing Height When the Sounding Is Too Shallow
8.8 Input Data Needs for AERMAP
8.9 Information Passed by AERMAP to AERMOD 
8.10 Wind Speed & Turbulence Limits Used in Model Calculations
8.11 Using Profiles for Interpolating Between Observations 
8.12 Using Measured Mixing Heights

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