This data set is a subset of the data from the 2006 ASA Data expo challenge,
https://community.amstat.org/jointscsg-section/dataexpo/new-item5.
The data are monthly ozone
averages on a very coarse 24 by 24 grid covering Central America, from Jan
1995 to Dec 2000. The data is stored in a 3d area with the first two
dimensions representing latitude and longitude, and the third representing
time.