Algorithm Theoretical Basis Documents (ATBD's) were developed for every EOS (Earth Observing System) instrument product including MODIS. In ATBD's, both physical theory and the mathematical procedures and possible assumptions have been applied for the calculations that have to be made to convert the radiances received by the instruments to geophysical quantities. As such the ATBD's serve as useful background for understanding the development of the MODIS products and their application in the study of land, ocean, atmosphere and Level 1 characteristics of the Earth-atmosphere systems. Some of the ATBD's are the original documents for a MODIS product while others have been updated or supplemented by other approaches that help the user community to effectively use the MODIS products. The following links can be used to examine ATBD's as well as User Guides and other information enabling the use of MODIS products:

Level 1 ATBD's
For best information go to:

Atmosphere ATBD's
For background and overview go to:
For specific information about ATBD's go to:

Land ATBD's
Two approaches can be used to access ATBD's and other useful information.

1. The first approach is to go to the Land Processes Distributed Active Archive Center (LPDAAC) and the MODIS Products found at: There one can click on the MODIS product of interest and then on “Links” to find descriptions and discussion of the ATBD, User Guide and other useful subjects.

2. The second approach is to the MODIS Land website. This is at: There one can click on “ Products” and go to the MODIS products of interest and then click on “User Guide” or “ATBD” or the P.I. website for current information.

Ocean ATBD's
All information about MODIS ocean products should be gained at: The ocean products have moved away from using ATBD's and have a user forum and other approaches to providing the user community with information on how to use ocean products and latest updates.