All of the data available within this site are subject to updating at any point. Different data may be substituted or the data-processing and image-rendering algorithms may be changed. The main purpose of this site is to provide a historical look at the development of atmospheric ozone, but that purpose does not extend to keeping a historical archive of all the data versions and processing algorithms used.
On many days there are missing data points in parts of the data fields, and some days may have all of the data missing. To provide for visual continuity, these missing data points are interpolated using various spatial and temporal methods. The interpolated values are used in calculating quantities such as ozone hole area, but are never used in quantities such as minimum ozone.