In short, the retrieval algorithm produces a pair of zonal mean abundance fields for each day, one for the daytime part of the orbit and the other for the nighttime part on a grid with 6 surfaces per decade change in pressure (∼3 km). These are obtained from a 10◦ latitude bin zonal mean of radiances (sorted by solar zenith angle) interpolated onto 6 surface per decade pressure grid using the limb tangent pressure from the standard production data. To minimize biases, day-minus-night differences between 10 and 1 hPa must be used as a more accurate measure of daytime HO2. Due to the small spectral signature of HO2 in the MLS radiances, significant averaging (such as monthly zonal means) is required to obtain scientifically useful results. This document is for MLS L3 v5 products.