This directory contains zonal mean averages of the version 7
Nimbus 7 TOMS ozone data.  The monthly zonal means are in the
file zm_month.n7t, while the daily zonal means are in files named
for each year - for example: zmday_79.n7t.  The averages are for
5 degree latitude zones, area weighted.  At least 75% of possible
data in a given zone must be present for the mean to be
calculated.  In 1978 and 1979 there were missing days (6 missing
in 1978, 29 missing in 1979) when the TOMS instrument was turned
off to conserve power.  In the later years there is at least some
data every day.