Format of MST radar radial data files

Users are encouraged to make use of Version-2 radial files.
Click here to find out more about the different versions of the signal processing.

File contents
These files contain 12 minute averaged radial (i.e. along-beam) profiles of the radar return parameters (signal-to-noise ratio, signal power, Doppler shift and signal width) for different beam pointing directions. The same data are stored in ASCII format files - please contact the NERC MST Radar Facility Project Scientist for more details.
Click here to find out about the contents of other files.

File naming convention:

YY is a 2-digit year [00 - 99]
MM is a 2-digit month [01 - 12]
DD is a 2-digit day [01 - 31]
Click here for the background to the file naming convention.

File location: /badc/mst/data/mst-products-v0/radial/
Click here for the location of other files.

Archiving convention: YYYY
Click here for a further explanation.

File availability
1990 to the present.

File format
The data are recorded in non-standard format binary files as descibed below:

                        RADIAL WIND FILES

        File name :- RDFyyMMdd.DAT   where yyMMdd is the date.

        RECORD   -  36 BYTES

        Data is FORMATTED unless stated otherwise.
        For UNFORMATTED data:
        B  = BYTE
        I2 = INTEGER*2 (2 byte integer)
        I4 = INTEGER*4 (4 byte integer)


        Each RDF file contains the results of processing the Doppler 
        spectra from the MST Radar for one day.

        The results for each Doppler spectrum include:
          the centre frequency of the peak,
          the signal level,
          the signal to noise ratio and
          the estimated peak width.

        The RDF file is formed by concatenating all Radial wind (RW) files 
        obtained on one day. These RW files have filenames RWyyMMdd_hhmm.nn 
        where hhmm is the time (UT) of the start of that data subset 
        and nn is the duration in minutes.

        Each set of radial winds is calculated from the doppler spectra
        from one beam direction (dwell) averaged over 12 minutes of
        viewing in that direction.

        The RDF file contains one header of peak extraction parameters
        then alternating dwell header records and data records.

        Peak Extraction Parameter records provide information about
        the operating and processing parameters that were used.

        Some records have an I1 identification field at the start to show 
        the type of information they contain.

        The timing of the data can be read from the dwell header. 

        The Peak Extraction Parameter Records only occur once per day,
        at the start of the RDF file after the first RW file name.
        The Dwell Header Records precede the Data Records to which
        they apply. 
        Ident   Record                          Comment
        None    Name of RW data file.           Name of Radial wind file
                                                that the data came from.
         4      Peak extraction parameters.     Before first RW file only.

              DWELL HEADER
        None    Dwell header                    for the first dwell
        None    Peak frequency & (s,s/n,dF)     first bin
        None    Peak frequency & (s,s/n,dF)     second bin
                  etc. for six bins             first data record
                  repeated                      for all height bins

              DWELL HEADER
              DATA                              for the next dwell
              DWELL HEADER
                  etc.                          to the end of the RW file    

        None    Name of RW data file.           Name of next Radial Wind file
              DWELL HEADER                                   
              DATA                              the first dwell of this file
         0      Trailer.


        Radial wind file name record.

        Name of RW file data came from.                 A20

        Peak extraction parameter record.

          Contains parameters relating to the methods used to find the
          spectral peak and estimate the doppler shift.

        Identifier for Peak extraction record ( 4 ).    I1
        Algorithm number.                               I2
        Peak width factor.                              F4
        DC spike removal parameters.                  4*I2

        Dwell header
          Information relating to a dwell.

          The following data is UNFORMATTED.

        Dwell number in cycle.                          I2
        Antenna beam number.                            I2
        Radar pulse length, microsecs                   I2
        Complementary code number.                      I2
        Pulse repetition interval, microsecs ( IPI ).   I2
        Total integration count ( NPP ).                I2
        Length of FFT ( LFT ).                          I2
        Number of FFTs that have been averaged.         I2
        Receiver filter (microsecs) (1/bandwidth)       I2
        MST run number.                                 I2 
        Mean time, yy MM dd  hh mm ss .               6*B
        First height bin range (NH1,NH2).             2*I2
        Second height bin range (NH3,NH4).            2*I2
        Height bin increment.                           I2

        Data record.
          Information derived from Doppler spectra.

          Get heights from the bin parameters in the dwell header:
          Data bins are NH1 to NH2 followed by
          NH3 to NH4 if upper height data was collected.

          The following data is UNFORMATTED.

        Doppler frequency of peak ( milli Hertz )       I2

        The 3 values below given as a 4 byte integer    I4

        Signal to noise, ( 0.1 dBs ) + 1024           11 Least Significant Bits
        Signal strength, ( 0.1 dBs ) + 1024      Next 11 bits
        Width of peak ( FFT points )                  10 Most Significant Bits

          Width of peak can be expressed in Hz 
          by multiplying the value in FFT points by 
          1.0 / ( 1E-6 * IPI * NPP * LFT )
          Thus data for one height bin uses I2+I4=6 bytes

        Each data record includes data for 6 bins   ( 36 bytes )
          The last record of a dwell usually has less.

        Trailer record.
          Indicates end of data in the file.

        Identifier for Trailer record ( 0 ).            I1


	Height at range bin n is given by :-  Ht = (n - Bz) * HI

	Bz is the sea level range bin,
          derived as follows from dwell header parameters:
	NRX = Receiver filter (microsecs).
	LTX = Transmitter pulse width (microsecs).
	If NRX = 1  Bz = 5.7 ( unless LTX = 1 when Bz = 5.2 )
	If NRX = 2  Bz = 6.7
	If NRX = 4  Bz = 8.7
	If NRX = 8  Bz = 12.7

	HI is the height increment per bin.
          derived as follows from dwell header parameter:
	NBM = Antenna beam number.
	If NBM = 0               HI = 0.15 Km.    ( Vertical )
	If NBM = 1,3,5 or 7      HI = 0.1496 Km.  ( 4.2 Deg. )
	If NBM = 2,4,6 or 8      HI = 0.1484 Km.  ( 8.5 Deg. )
	If NBM = 9,11,13 or 15   HI = 0.1492 Km.  ( 6.0 Deg. )
	If NBM = 10,12,14 or 16  HI = 0.1467 Km.  ( 12.0 Deg.)

        This description was last updated 16 February 1995.

Internal Links:
Return to the top of the page
Gaining access to the data
File naming convention
Data archiving convention
Data locations
The differences between signal processing versions
The contents of other data files