Abstract:
This data product contains TOMS/Nimbus-7 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.
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.
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:
Eck, T. F., Bhartia, P. K., Kerr, J. B., Satellite estimation of spectral UVB irradiance using TOMS derived total ozone and UV reflectivity, Geophy. Res. Letters 1995, 22, 611-614
Herman, J.R., et al., "Meteor-3 Total Ozone Mapping Spectrometer (TOMS) Data Products User's Guide." NASA reference publication 1393, 1996.
McPeters, R.D., et al., "Nimbus-7 Total Ozone Mapping Spectrometer (TOMS) Data Products User's Guide." NASA Reference Publication 1384, April 1996.
Krueger, A., M. Schoeberl, P.Newman, and R.Stolarski, June 1992. "The 1991 Antarctic Ozone Hole; TOMS Observations", Geophys. Res. Letters, 19: 1215-1218.
Schoeberl, M.R., A.J. Krueger, and P.A. Newman, 1986. 'The Morphology of Antarctic Total Ozone As Seen by TOMS,' Geophys. Res. Letters, 13:1217-1220.
