Algorithm Theoretical Basis Document (ATBD) for the S5p+I: SO2 Layer Height product

This is the Algorithm Theoretical Basis Document (ATBD) describing the theoretical basis
and the implementation of the S5p+I SO2 Layer Height product from Sentinel-5P/TROPOMI measurements.

The purpose of the document is to give detailed mathematical description of the algorithm and to discuss the necessary input and auxiliary data, and the output that will be generated. In addition, information about the expected size of the product, expected calculation times, and the expected accuracy are provided. The document is part of the ESA S5p+I SO2LH project.