Format of the DMSP
SSIES data
The
ascii data presented through the search page on this site are given in the following
format:
First
the filename (e.g. f13_rl011211515.txt meaning F13, 2001, doy 121, starting
time 1515 UT) is given on the first line. The second and third lines give the
descriptive headings for each column. Each following line lists one segment
of data at a four-second resolution in the following order:
- DATE
(in YYYDDD format, e.g. 101121; note that 1999 = 99, 2000 = 100, 2001= 101,
etc.)
- TIME
(in seconds of the day; note that if the file goes past midnight UT then the
time starts over at zero)
- QUALITY
FLAG for the RPA data (1 = good, 2 = caution, 3 = poor, don't use,
4 = undetermined)
- QUALITY
FLAG for the IDM data (1 = good, 2 = caution, 3 = poor, don't use,
4 = undetermined)
- ALTITUDE
(in kilometers)
- GEOGRAPHIC
LATITUDE (in degrees and tenths of degrees)
- GEOGRAPHIC
LONGITUDE (east longitude in degrees and tenths of degrees)
- MAGNETIC
LATITUDE (in degrees and tenths of degrees)
- MAGNETIC
LOCAL TIME (in hours and tenths of hours)
- VX
(in meters/second; + is in the direction of the spacecraft's velocity; -9999.0
is fill data)
- VY
(in meters/second; + is horizontal to the left as you face in the direction
of the spacecraft's travel; -9999.0 is fill data)
- VZ
(in meters/second; + is in the direction away from the center of the Earth;
-9999.0 is fill data)
- RMSX
root mean square error of the RPA curve fit; dimensionless
- SIGMA
VY (the standard deviation of the 24 (nominally) measurements
of Vy averaged together for this four-second period)
- SIGMA
VZ (the standard deviation of the 24 (nominally) measurements
of Vz averaged together for this four-second period)
- Ni
(the plasma density in number of ions per cubic centimeter; these data come
from the scintillation meter, not the RPA)
- FRACTIONAL
O+ (the fractional amount of O+ in the plasma; -9999.00 is fill data)
- FRACTIONAL
He+ (the fractional amount of He+ in the plasma; -9999.00 is fill
data)
- FRACTIONAL
H+ (the fractional amount of H+ in the plasma; -9999.00 is fill data;
note that these three amounts may not add up to 1.0, in times of minute amounts
of light ions the analysis may return small negative values for H+ and He+.
These should be ignored.)
- Ti
(the ion temperature in degrees K; -9999.0 is fill data)
- Te
(the electron temperature in degrees K; -9999.0 is fill data)
- IDM
# (this is the number of measurements from the IDM averaged together
to form the four-second average for Vy and Vz each; nominally there are 24
(6 per second) but it can drop to zero under disturbed conditions; this serves
as a secondary quality flag for Vy and Vz)
These files are
produced by a fortran program. If you wish to use the a fortran read statement
to read your copy of these files, the format is:
101 format(0pf10.0,f8.1,2i2,f7.1,f8.2,f8.2,f8.2,f8.2,
$ 3f8.1,f8.2,2f8.1,1pe15.7,0p,3f9.2,2f7.0,i7)