stat-make

stat-make compiles statistics (.stat) files from .fit files. The statistics are produced for sixteen 'summary points' numbered 0 to 15 (see Statistics).

.stat file structure

A two hour .stat file usually contains 72 scans (each of 100s duration) of statistics information, though this number may be lower if data gaps are present, or up to 73 under exceptional circumstances.

For each scan a header with the following structure is present:

STRUCTURE /stat_head/ INTEGER*2 stat_rev_no ! statistics revision number INTEGER*2 st_id(2) ! station id (west, east) INTEGER*2 year ! year INTEGER*4 rec_time ! time, secs of year INTEGER*2 tfreq ! frequency RECORD /rev_no/ rev ! fitacf revision number INTEGER*2 no_scans ! number of scans in stats data INTEGER*2 gipercent(2) ! f-o-v %, ground and ion scatter INTEGER*2 stat_res(3) ! reserved for future use INTEGER*2 ndata ! number of data blocks following END STRUCTURE STRUCTURE /rev_no/ !this defines the revision number structure BYTE major BYTE minor END STRUCTURE

The header structure is shared by the post-integrated statistics files (see stat-int), no_scans containing the number of scans integrated; in the case of non-integrated data (produced by stat-make), no_scans=1.

gipercent() contains the percentage of the field of view that is filled with ground scatter (gipercent(0)) and ionospheric scatter (gipercent(1)).

ndata contains the number of the summary points for which backscatter information exists.

The header block for each scan is followed by ndata data blocks with the following structure:

STRUCTURE /stat_data/ INTEGER*2 point_id ! id of point INTEGER*2 glat ! geographic latitude of point INTEGER*2 glon ! geographic longitude of point INTEGER*2 atten ! attenuator setting INTEGER*2 txstat ! low power Tx status INTEGER*2 gscat ! ground scatter flag INTEGER*4 noise ! noise level INTEGER*4 noise_lev ! in A-to-D converter units INTEGER*4 noise_lag0 ! lag0 power-noise INTEGER*4 noise_vel ! velocity from noise ACF INTEGER*4 pwr_lag0 ! log0 power, dB INTEGER*4 pwr_l ! power, dB, lambda fit INTEGER*4 pwr_s ! power, dB, sigma fit INTEGER*4 vel ! velocity, m/s INTEGER*4 width_l ! spectral width, l-fit, m/s INTEGER*4 width_s ! spectral width, s-fit, m/s INTEGER*2 elev ! elevation angle END STRUCTURE

point_id (0-15) indicates the summary point to which the data refers, glat and glon giving its approximate geographic location.

gscat indicates if the backscatter is ionospheric (gscat=0) or ground (gscat=1).

.stat file location and creation

Statistics files are regularly created (at the same time as the archiving of the .fit data) and consequently stat-make will not generally be needed by the user. .stat files exist in /cutlass/statistics/finland/yy or /cutlass/statistics/iceland/yy, where yy is a two digit number representing the year.

However, to create .stat files:

1) Change to the destination directory for the .stat files

2) Execute:

/people/ets/Cutlass/statistics/stat-make file

where file is of the form 95022816f. An error is generated if a corresponding .fit file does not exist. stat-make uses the shell variable SD_FITROPEN_PATH to search for .fit files, in the same manner as plot_radar.

Revisions and bugs

Prior to January 1996 the statistics revision number was 69, and was as described above. As of January 1996 the revision number is 70, the following changes having been made:

  • A bug existed such that the value of stat_head(0).rec_time (i.e. the time of the first scan) of some of the .stat files held a spurious value. This has been corrected (I think).
  • stat_data.glat and stat_data.glon contained the geographic latitude and longitude of the summary point. This has now changed to beam and range gate within the radar field-of-view.
  • stat_head.stat_res(1) now contains the scan_id of the data from which the statistics file was created.