FILE_USAGE_ASCII.TXT

The SNOE data files have passed through five steps of processing in order
to reach their final state. Levels 3 and 4 are being made available to the
science community through this dataset. The contents and layout of those
files are described in this document.

Note that different operating systems and languages may have the arrays
transposed, use one (not zero) based arrays, etc.

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PRODUCT: Nitric Oxide Volume Density (molecules/cm^3)
	 Level Three Data

DESCRIPTION: Orbit average files containing latitude, altitude, and
longitude resolution. The files have been written as ASCII files. The
following naming convention has been used: SNOE_t_y_d_o.ascii, where 't'
is the type of the file, either 'geo' or 'mag' depending on the coordinate
system used to bin the data. 'y' is the year of the data (1998, 1999, or
2000). 'd' is the doy of the data, a number between 1 and 366.  'o' is the
orbit of the day, a number between 0 and 14.

RESOLUTION: 5 degrees latitude, 3.3 km altitude, 24 degrees longitude

SIZE: The dimensions of the file are 38 (latitude) by 20 (altitude). There
are 15 of these files per day, and 935 days in the dataset.

FILE ORGANIZATION: A graphical representation of the data is shown in the
file file_layout_l3.jpeg. This is an image file in the JPEG format.  You can
use your favorite image viewer or web browser to view this file.

For each orbit, a file is organized as follows:

The X dimension (latitude) is from index 0 (90 degrees south) to index 36
(90 degrees north) in steps of 5 degrees. The final column, index 37, is a
data location parameter column containing the altitudes.

The Y dimension (altitude) is from index 0 (150.0 km) to index 16 (96.6
km) in steps of 3.3 km. Y equal to index 17 is a data location parameter
row containing the values of the center latitudes of each bin. Y equal to
index 18 is the average longitude of each latitude bin. Y equal to index
19 is a data location parameter row containg the UTC value (in seconds
into the day) of each latitude bin.

There are 3 more elements in the array, index (37,17), (37,18), and
(37,19). These contain the day-of-mission (0 through 935), the day-of-year
(0 through 366), and the year (1998, 1999, or 2000) of the file,
respectively.

Note that a value of -999 in UTC or Longitude means there is no valid data
in that column. A value of 0 in the nitric oxide density means there is no
valid data for that grid point.

______________________________________________________________________________
PRODUCT: Daily Averages of Nitric Oxide Density (molecules/cm^3)
	 Level Four Data

DESCRIPTION: Daily average files containing latitude and altitude binned
data.  The files have been written as ASCII files. The following naming
convention has been used: SNOE_t_y_d.ascii, where 't' is the type of the
file, either 'geo' or 'mag' depending on the coordinate system used to bin
the data. 'y' is the year of the data (1998, 1999, or 2000), and d is the
doy of the data, a number between 1 and 366.

RESOLUTION: 5 degrees latitude, 3.3 km altitude.

SIZE: The dimensions of the file are 38 (latitude) by 18 (altitude). There
are 935 of these files, one for each day in the dataset, from yyyyddd
1998070 to 2000274.

FILE ORGANIZATION: A graphical representation of the data is shown in the
file file_layout_l4.jpeg. This is an image file in the JPEG format.  You can
use your favorite image viewer or web browser to view this file.

For each day, a file is organized as follows:

The X dimension (latitude) is from index 0 (90 degrees south) to index 36
(90 degrees north) in steps of 5 degrees. The final column, index 37, is a
data location parameter column containing the altitudes.

The Y dimension (altitude) is from index 0 (150.0 km) to index 16 (96.6
km) in steps of 3.3 km. The final row, y equal to index 17, is a data
location parameter row containing the values of the latitudes.

There is one last element in the array, index (37,17). This contains the
day-of-mission (0 through 935) value for the day.

A value of 0 in the nitric oxide density means there is no valid data for
that grid point.