Model Change Bulletin              
              
                            MCB#2                 2/14/90

                      MPRM (dated 90045)



        This Model Change Bulletin is formal notification of the corrections
to the Meteorological Processor for Regulatory Models (MPRM). This version
replaces all previous versions of MPRM for regulatory use.

         REVISION TO METEOROLOGICAL PROCESSOR FOR REGULATORY MODELS

        In September, 1988 version 1.1 of a Meteorological Processor for 
Regulatory Models was made available.  In January, 1990 in the course of 
following up on an inquiry from a user of the processor, an error was 
discovered in the FORTRAN coding.  National Weather Service (NWS) hourly 
observations of wind direction and speed were being handled improperly.  As 
a result of the error, calm wind conditions, encoded within the NWS 
observation as zero wind speed and zero wind direction, were being treated 
by the processor as missing data.  This forced users to perform the calm 
wind adjustment procedures themselves. 

        The processor encodes missing wind speeds as -9 and missing wind 
directions as -99.  Whereas, calm winds are adjusted such that the wind 
speed is set to 1 m s-1 and the wind direction is set equal to the last 
valid wind direction.  

        The FORTRAN code was easily corrected to affect proper treatment of 
NWS calm wind conditions.  The FORTRAN changes only affected one subroutine 
WS1NWS.  To reflect that a change had been made to the model, the model 
version number was changed from 1.1 to 1.2.  Changing the version number 
required updating FORTRAN code in a file named MASTER.FOR.  

        It is anticipated that future upgrades may occur to MPRM.  In order 
to allow orderly recording of such events, a new section was added to the 
MPRM user's guide entitled, Revision History.  The purpose of this section 
is to record when revisions occur and to briefly indicate the nature of the 
revision.  Other minor edits were made in other sections of the user's 
guide to account for the version number change and the revised organization 
names.  No text changes of a technical nature were required. 

        For those who have copies of the MPRM files, you need only to download 
DISK1 and DISK2 for the new PC executables, and DISK3 and DISK4 for the new 
code listings.