6.8 Treatment of Missing Data

Missing or invalid data should be flagged or replaced as appropriate depending on the model to be used. Note that the ISCST3 and AERMOD models recognizes specific flags for missing data; however, many models do not recognize flags and will not accept missing or invalid data. For use in these models, data bases with isolated one-hour gaps should be filled with estimates based on persistence or linear interpolation. Application specific procedures should be used for filling longer gaps; guidance for developing such procedures is provided in Section 6.8.1. Substitutions for missing data should only be made to complete the data set for modeling applications; substitution should not be used to attain the 90% completeness requirement for regulatory modeling applications (Section 5.3.2).

6. METEOROLOGICAL DATA PROCESSING
  6.1 Averaging and Sampling Strategies 
  6.2 Wind Direction and Wind Speed 
      6.2.1 Scalar Computations 
      6.2.2 Vector Computations 
      6.2.3 Treatment of Calms  
      6.2.4 Turbulence 
      6.2.5 Wind Speed Profiles  
  6.3 Temperature 
      6.3.1 Use in Plume-Rise Estimates  
      6.3.2 Vertical Temperature Gradient 
  6.4 Stability 
      6.4.1 Turner's method  
      6.4.2 Solar radiation/delta-T (SRDT) method 
      6.4.3  _E method 
      6.4.4 _Amethod 
      6.4.5 Accuracy of stability category estimates 
  6.5 Mixing Height 
      6.5.1 The Holzworth Method  
  6.6 Boundary Layer Parameters  
      6.6.1 The Profile Method 
      6.6.2 The Energy Budget Method  
      6.6.3 Surface Roughness Length 
      6.6.4 Guidance for Measurements in the Surface Layer 
  6.7 Use of Airport Data 
  6.8 Treatment of Missing Data  
      6.8.1 Substitution Procedures 
  6.9 Recommendations