This directory contains gridded files for the tropospheric ozone climatology
described in:

J. A. Logan, An analysis of ozonesonde data for the troposphere:
Recommendations for testing 3-D models, and development of a gridded
climatology for tropospheric ozone, J. Geophys. Res., 104, 16,115-16,149,
1998.

This paper must be cited as the source of this climatology.

Direct any questions and feedback to:
---------------------------------------------------------------------
Jennifer A. Logan                          Phone: 617-495-4582
Harvard University                         Fax:   617-495-9837
108 Pierce Hall
29 Oxford Street                           e-mail: jal@io.harvard.edu
Cambridge MA 02138
U.S.A.
----------------------------------------------------------------------
FILE DESCRIPTION

Files with ozone monthly means are called:
ozone.13.4x5.xx 
(xx=01,02,03,04,05,06,07,08,09,10,11,12), xx=month, Jan.-Dec. 

UNITS:  ppb

The files contain monthly mean ozone values in ppb for a grid of 4 deg.
latitude by 5 deg. longitude for 13 pressure levels.

The pressure levels are (in mbar):
1000, 900, 800, 700, 600, 500, 400, 300, 250, 200, 150, 125, 100

The grid is 72x46, with 72 boxes for longitude and 46 boxes for latitude. 

The longitude boxes are centered at 180 degrees, i.e., their boundaries are
-177.5, -172.5, -167.5, ... , -2.5, 2.5, ... , 177.5.

The latitude boxes have their boundaries at -90,-88,-84,-80, ...-8,-4,0,4,8,
..., 84,88,90.
Thus all boxes are 4 degrees EXCEPT for boxes number 1 and 46 which are 2 deg.

The  indexing is from West to East, from South to North and from
high pressures to low pressures.  

For example, O3XXX(1,2,5) corresponds to ozone value for a gridbox with
boundaries 177.5W-177.5E, 88S-84S at pressure level 600  mbar.

FORMAT:

The files ozone.13.4x5.xx were written to the disk as formatted files,
using the following FORTRAN f77 statements:

       WRITE(30,901) O3XXX
901    FORMAT(9E10.3)

and thus could be read the same way:

       READ(30,901) O3XXX
901    FORMAT(9E10.3)

O3XXX is 3 dimensional real array described as

       REAL O3XXX(72,46,13)  .