Digital Precipitation Array (DPA) Product Decoders

The decoder GET_DPA_DATA returns information on the radar site, volume scan time, radar operating mode, and on the radar data itself. The array IFIELD() contains values 0-255, which can be converted to physical units (mm rainfall ) by using the relationships:

dBA = -6.125 + IFIELD() x 0.125
Rainfall (mm) = 10 (dBA / 10)

An IFIELD value of 0 indicates zero rainfall; a value of 255 indicates a grid box more than 120 nautical miles from the radar site.

Note that all input and output variables are INTEGER*4 except:

     IVAL(), IHEADER(), ITRAILER() : BYTE or CHARACTER*1

     IFIELD(,) : INTEGER*2



EXPLANATION OF CALLING SEQUENCE:
 
     CALL  GET_DPA_DATA(IVAL,MSGLEN,ISITE,
     1   ISITE_LAT,ISITE_LON,ISITE_ELEV,
     2   IYR,IMONTH,IDAY,IHR,IMINIT,ISEC,
     3   IPROD,MAXVAL,IVCP,IFIELD,NCOLS,NROWS,
     4   NCOLSP,NROWSP,IHEADER,LEN_HEADER,ITRAILER,LEN_TRAILER,ICODE)

IVAL()         =     BYTE OR CHARACTER*1 ARRAY CONTAINING DPA
                     MESSAGE.  MUST BE DIMENSIONED .GE. MSGLEN (INPUT).
MSGLEN         =     LENGTH OF INPUT MESSAGE IN BYTES (INPUT)
ISITE          =     WSR-88D NUMERIC SITE ID (OUTPUT)
ISITE_LAT,
ISITE_LON      =     SITE LAT/LON (DEG E, DEG N), DEG X 1000 (OUTPUT)
ISITE_ELEV     =     SITE ELEVATION, M MSL (OUTPUT)
IYR,IMONTH,IDAY=     PRODUCT VOLUME SCAN DATE (OUTPUT)
IHR,IMINIT,ISEC=     PRODUCT TIME, UTC (OUTPUT)

IPROD          =     PRODUCT CODE NUMBER (OUTPUT) 
MAXVAL         =     MAXIMUM VALUE IN THE RASTER FIELD (OUTPUT)
IVCP           =     OPERATING VOLUME COVERAGE PATTERN (OUTPUT)
IFIELD(,)      =     RETURNED VALUES (DATA LEVELS) FOR THE FIELD
                     (OUTPUT); INTEGER*2 VARIABLE.  SHOULD BE
                     DIMENSIONED NCOLS,NROWS IN CALLING ROUTINE

                     IFIELD() VALUES ARE CONVERTED TO RAINFALL BY:

                     DBA = -6.125 + IFIELD()*.125
                     RAINFALL(MM) = 10.**(DBA/10.)

                     IFIELD() = 0 INDICATES ZERO RAINFALL; 255 INDICATES
                     NO RADAR COVERAGE

NCOLS,NROWS    =     DIMENSIONS OF IFIELD(), SET TO .GE. 131 (INPUT)
NCOLSP,NROWSP  =     ACTUAL NUMBER OF ROWS AND COLUMNS IN OUTPUT
                     PRODUCT (OUTPUT) (ROWS=COLUMNS IN 88D FILES)
IHEADER()      =     BYTE ARRAY WITH COPY OF HEADER.  SHOULD BE
                     DIMENSIONED 160 IN CALLING ROUTINE (OUTPUT)
LEN_HEADER     =     ACTUAL NUMBER OF BYTES OF INFORMATION IN
                     IHEADER() (OUTPUT)
ITRAILER()     =     CHARACTER*1 ARRAY WITH TEXT INFORMATION
                     ATTACHED AT END OF FILE (IF ANY). SHOULD BE
                     DIMENSIONED BY 20 000 IN CALLING ROUTINE (OUTPUT)
LEN_TRAILER    =     ACTUAL NUMBER OF BYTES OF DATA IN ITRAILER(). 
                     WILL BE SET 0 IF NO TRAILER EXISTS (OUTPUT) 
ICODE          =     OUTPUT RETURN CODE, CONDITIONS AS FOLLOWS:
                     0 : DECODED PROPERLY      
                     2 : NOT A RECOGNIZED DPA PRODUCT
                     3 : NCOLS/NROWS TOO SMALL FOR PRODUCT
                     4 : PRODUCT TOO LARGE FOR MSGLEN

Known Deficiencies:

None

Related Documents:

Federal Meteorological Handbook 11: Doppler Radar Meteorological Observations Part C, WSR-88D Products and Algorithms.

Interface Control Document for Product Specification (Document Number 2620003A, WSR-88D OSF, June 26, 1998)

Interface Control Document for the RPG Associated PUP ( Document Number 2620001A, WSR-88D OSF, June 26, 1998)

Change History Log:

The latest version of the WSR-88D DPA product decoder can be downloaded and utilized free of charge, subject to the usual  NWS disclaimer, click here to download a copy.