WFDOAS V1.0 Delta-Validation Report

Abstract

This document serves two purposes, first, it contains a reply to the comments made by the Panel Review (see PANEL–REVIEW) and secondly it summarizes the results from the Delta Validation that was carried out after the review. The comments made by the review were fair and well balanced and the reviewers are thanked for their thoughtful suggestions. It is also agreed that all three consortia using different algorithm concepts have significantly improved total ozone retrieval as compared to the current GOME data processor version 3.0. On first sight it appears that the overall performance of all algorithms (TOGOMI, GODFIT, and WFDOAS) have produced consistent and similar results such that it was indeed hard for the review board to decide which of the algorithm is the most appropriate to succeed Version 3. Since GODFIT uses online radiative transfer calculations its processing speed is about a factor of five slower than compared to TOGOMI and WFDOAS. It was therefore decided to inter-compare TOGOMI and WFDOAS with GDOAS, a standard DOAS retrieval, that has been used by BIRA to assess the GDP V3 data quality. GDOAS closely resembles the GOME Data Processor as described in Section 6.1 in GODFIT–VALREPORT. Major differences to GDP V3 are the inclusion of the ozone filling-in like in WFDOAS, TOGOMI, and GODFIT and the use of an updated surface albedo climatology using the minimum Lambertian equivalent reflectivity database from Koelemijer et al. (2002).