PDS_VERSION_ID     = PDS3
RECORD_TYPE        = STREAM
OBJECT             = TEXT
  PUBLICATION_DATE = 2016-05-16
  NOTE             = "PDS_EVENT_WIND_FORMAT document
                      in the Viking Lander 2 seismology experiment archive."
END_OBJECT         = TEXT
END

VPDS EVENT WIND FORMAT

The data file EVENT_WIND_SUMMARY.TAB is a summary of the Viking Seismometer data
Event mode records, intended as a high-level index to events of interest, and
for large-scale correlation with meteorological data. In Event mode, raw
readings were compressed in the instrument itself by recording the number of
positive-going zero crossings in a 1.01s interval, and recording an envelope
value generated by digital filtering.

The file was generated by parsing the raw ('VUSA') files, and where the Event
mode flag was detected and valid data found, the record (typically 51 lines
long) are summarized into a single record (one line) in the summary file. The
location (file, line number) of the original data in the VUSA file is indicated
in the summary to allow it to serve as an index – the raw data for events of
interest can therefore be easily located. Additionally a new record number is
provided  in the first column, which gives the line in the reformatted raw high
rate record. The reconstructed sol, hour, minute and second are provided, as
well as the original record length. The data in the record are examined and
several parameters of interest are extracted and listed in the summary.
Specifically, these are the median, maximum, minimum, and rms values of the X-
axis amplitudes, as well as the average number of zero-crossings  (note that
these amplitudes are themselves an envelope value – see Anderson et al., 1977
for details of the on-board data processing). The rms X value is reported as an
integer equal to 100 times the root mean square of the original data (multiplied
by 100 to provide good dynamic range while preserving a compact integer
presentation).   Also reported are the (similarly formatted) rms Y value,
average Y-zero-crossings, rms Z value and average Z zero-crossings. The zero
crossings are simple mean values, truncated to integers.

To these summary parameters are appended  nearest Viking meteorology
measurements, processed by J. Murphy. Readings of wind speed, pressure, wind
direction and air temperature are reported, as close as possible in time to the
start of the seismometer acquisition. : the time from the nearest available
meteorology measurement is noted in the final column.

Original VUSA files are archived at JAXA.

The data file was generated by R. Lorenz on 12/12/2016 and may be cited by 
'R.D. Lorenz, Y. Nakamura, J. Murphy, Viking Seismometer Data Restoration and
Meteorological Application, VL2-M-SEIS-5-RDR-V1.0, Planetary Data System, 2016'.
This work was supported by the NASA Mars Data Analysis Program (MDAP) Grant,
Viking Lander Meteorology and Seismology, NNX12AJ47G.

Column  1
An ordinal number indicating the record in the present file and in the 
corresponding raw archive files

Column 2 
The time in decimal Sols corresponding to the seismic data acquisition

Column 3 
The file number of the original data  (i.e. file number 0101 corresponds 
to VUSA.0101.TXT).

Column 4
The line number in the original VUSA file to which the present record 
corresponds.

Column 5
The sol number of the mission on which the data were acquired.

Column 6 
The hour of acquisition start.

Column 7
The minute of acquisition start.

Column 8
The second of acquisition start. Note that the data in the VUSA file 
are reported at 1Hz, thus the end of acquisition is typically 51 seconds 
after this time.

Column 9
The median X-axis reading.

Column 10
The first X-axis reading in the record.

Column 11
The maximum X-axis reading in the record.

Column 12
The minimum X-axis reading in the record.

Column 13
100 times the RMS X-axis reading.

Column 14
100 times the RMS Y-axis reading.

Column 15
100 times the RMS Z-axis reading.


Column 16 
The mean number of X-axis zero-crossings in the record.

Column 17
The mean number of Y-axis zero-crossings in the record.

Column 18
The mean number of Z-axis zero-crossings in the record.

Column 19
The mission time in decimal Sols corresponding to meteorological data acquisition
(i.e. sol+(hr*3600.0+min*60.0+sec)/88775.24).

Column 20 
Windspeed (m/s).

Column 21
Pressure (mbar).

Column 22
Wind Direction (deg clockwise from North).

Column 23 
Air temperature (K). Note that this value has 
not been screened for possible lander thermal contamination  
(see Hess et al. 1977).

Column 24 
Time in seconds between closest wind measurement and the start 
of the seismic record (for the first and last sol of the file, 
this value should be ignored). Positive means the seismic data 
were acquired after the meteorology. 



This description was generated by R. Lorenz on 3/18/2016.