This data product contains TOMS/Earth Probe Ground Station Overpass Data Version 8 in ASCII format. The overpass data files contain the data derived from the best-matched TOMS field-of-view (FOV) to a site for every day the TOMS instrument was operational.

(The shortname for this Level-3 Earth Probe TOMS Product is TOMSEPOVP)
 
Four TOMS instruments were successfully flown on the following satellites:  Nimbus-7 (Nov. 1978 - May 1993), Meteor-3 (Aug. 1991 - Dec. 1994), Earth Probe (July 1996 - current), and ADEOS (Sep. 1996 - June 1997). The TOMS Earth Probe, Meteor-3 and Nimbus-7 data were reprocessed using the Version-8 algorithm by the Laboratory for Atmospheres at NASA Goddard Space Flight Center (Code 614).

Each overpass file contains four (4) header records, followed by all the data records.

HEADER RECORDS
--------------
The file header consists of four (4) records:

  1. Site name, ID, and location.
  2. Overpass program run information
  3. Column headings
  4. Marker record.

An example of the first header record is:

  Edmonton/Stony Plain, Canada  ID:  21   Lat:  53.55  Lon: -114.10  Alt:  766

In this example, the site ID number is 21, the latitude is 53.55N and
longitude is 114.10E, and the verified elevation is 766 m (above sea level).

The FORTRAN format code for reading the first header record is:

  (A30, 4X, I3, 7X, F7.2, 7X, F7.2, 7X, I4)

An example of the second header record is:

  EarthProbe TOMS V.8 Overpass - Generated: 3-January-2006

This indicates the spacecraft instrument, the data version used to generate
the overpass data, and the date on which the file was generated (created or
updated).

The third header record contains the column headings for the data records.
The header looks like this:

  MJD   Year Day sec-UT SCN  LAT     LON  DIS  PT  SZA  OZONE   REF   A.I.   SOI

The contents of each column is described below in the section on Data
Records.

The fourth header record simply contains a pound-sign (#) in the first
column, and signals that the data begin with the next record in the file.

DATA RECORDS
------------

Each data record contains fourteen (14) values. They are as follows.

 MJD     Modified Julian Day. Astronomical Julian Day number, less
   2,400,000.5. The number is given to the nearest 1/10 day.

 Year    The four-digit Gregorian year number of the TOMS measurement.

 Day     The day number (day 1 through 366) of the TOMS measurement.

 sec-UT  The number of seconds from midnight, Universal Time. on the day
   specified by Year and Day.

 SCN     TOMS instrument scan position (1--35 for N7, M3, EP; 1--37 for
   Adeos)

 LAT     Latitude of the center of the IFOV.

 LON     Longitude of the same.

 DIS     Distance from site and IFOV center position, in km.

 PT      Terrain pressure at IFOV center, in (atm x 100)

 SZA     Solar zenith angle, in degrees, at time and location of IFOV

 OZONE   TOMS best total ozone, in Dobson Units (DU)

 REF     TOMS reflectivity at 380 nm (N7, M3) or 360 nm (EP,
   Adeos).

 A.I.    TOMS aerosol index.

 SOI     TOMS sulfur dioxide index.

The FORTRAN format code for reading a data record is:

  (F7.1, 1X, I4, 1X, I3, 1X, I5, 2X, I2, 1X, F6.2, 1X, F7.2, 1X,
   I3, 1X, I3, 1X, F5.2, 1X, F5.1, 1X, F5.1, 1X, F6.2, 1X, I4)This product can be used to compare TOMS with ground station data.