Model Change Bulletin (MCB) #2
                       
                         AERSURFACE version 19039_DRFT


                               February 8, 2019

       This draft version of AERSURFACE includes enhancements 
       to support processing of 1992/2001/2006/2011 Land Cover data,  
       including 2001/2006/2011 percent Impervious and Canopy data 
       to supplement concurrent land cover data.

       This version has been released primarily for review and comment 
       and is not a replacement for version 13016.
       The ZORAD option for determining roughness, provided in this 
       version, is equivalent to the method available in AERSURFACE
       version 13016 and may generally be appropriate for regulatory 
       applications, provided that such applications are done in 
       consultation with the appropriate reviewing authority, per 
       Section 8.4.2(b) of the Guideline. However, the research-grade
       ZOEFF option is the equivalent of an alpha option and is meant 
       only for review and is not intended for regulatory 
       applications at this time. 

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       This draft version of AERSURFACE includes the following 
       modifications relative to the previous version (dated 13016):
       
-----  Enhancements:

       1.  Path/Keyword interface similar to AERMOD, AERMET, and AERMAP. 
           NOTE: This draft version is not compatible with the
           redirected input from files generated with previous versions
           AERSURFACE.

       2.  Option to output surface values with appropriate AERMET
           keywords for the PRIMARY or SECONDARY meteorological tower
           location. (Default is PRIMARY.)
           
       3.  Option to separately characterize individual wind sectors as  
           either airport or non-airport for determining surface roughness
           length. Previous versions required all wind sectors to 
           be characterized as either airport or non-airport.
 
       4.  Option (ZOEFF) to compute surface roughness length based on the 
           Effective Roughness Model Coding Abstract (MCA) in which  
           an effective roughness is derived using an Internal Boundary 
           Layer (IBL) method to estimate the appropriate fetch from 
           the meteorological tower location based on the wind measurement 
           height and local land cover characteristics. Default option (ZORAD)
           uses a fixed radial distance from the tower (e.g., 1 km) 
           as in previous versions of AERSURFACE.

       5.  Option to supplement land cover data with percent impervious 
           and/or percent canopy data to derive surface roughness length. 
           Percent impervious and percent canopy data are supplied by the USGS 
           as part of the National Land Cover Dataset and are only 
           applicable to NLCD 2001, 2006, and 2011.

-----  Miscellaneous:

       1.  A valid range on the allowable height of the anemometer
           representing surface wind measurements has been imposed. 
           The valid range is 1.0 - 100.0 meters.

       2.  Draft AERSURFACE assumes all NLCD data, including
           land cover, percent impervious, and percent canopy are
           provided in GeoTIFF format. State binary files cannot be 
           processed with this draft version.

       3.  Modified to account for non-standard pixel spacing in the
           2001/2006/2011 NLCD products. Previous versions assumed a
           constant pixel size of 30 meters. The pixel spacing in more
           recent data may be slightly larger than 30 meters.

 

-----  MODIFIED FROM:        AERSURFACE
                       (Version Dated 13016)