(Multi-)TASTE: Ten years of quality tasting of Envisat and TPM atmospheric composition retrievals with the NDACC network
Lambert, Jean-Christopher1; Hubert, Daan1; Granville, José1; Aulamo, Osmo2; Blumenstock, Thomas3; Burrows, John4; De Backer, Hugo5; De Mazière, Martine1; Gil, Manuel6; Goutail, Florence7; Hase, Frank3; Hendrick, François1; Held, Gerard8; Ionov, Dmitry V.9; Johnston, Paul10; Kivi, Rigel2; Kopp, Gerhard3; Kreher, Karin10; Kyrö, Esko2; Mahieu, Emmanuel11; Mikuteit, Sabine3; Navarro Comas, Monica6; Notholt, Justus4; Pazmiño, Andrea7; Piters, Ankie12; Pommereau, Jean-Pierre7; Puentedura, Olga6; Richter, Andreas4; Susmann, Ralf13; Timofeyev, Yuri M.9; Van Roozendael, Michel1; Vigouroux, Corinne1; Warneke, Thorsten4; Wittrock, Folkard4; Wood, Stephen10; Yela Gonzalez, Margarita6

The independent calibration and validation of satellite experiments is a major goal of the Network for the Detection of Atmospheric Composition Change (NDACC). Since its official inception in 1991, this network of high quality remote sounding stations has contributed to the geophysical validation of not far from sixty atmospheric composition missions, including ESA’s ERS-2, Envisat and Third Party Missions. NDACC is expected to play a similar role in the future with the upcoming GMES/Copernicus Sentinel missions S5p, S4 and S5, and the candidate Earth Explorer PREMIER. NDACC instrumentation – DOAS/UV-visible and FTIR spectrometers, Dobson and Brewer spectrophotometers, lidars, MW radiometers and balloon-borne ozonesondes – complements satellite capabilities with continuous observations of species and at altitudes, precisions and resolutions not reachable from space. Dedicated initially to the monitoring of changes in the stratosphere with an emphasis on the evolution of the ozone layer, NDACC priorities and measurement capabilities have broadened considerably to encompass the overall atmospheric composition, from the troposphere up to the mesosphere, and links between climate change and atmospheric composition change. Latest updates on NDACC developments can be found on http://ndacc.org

Building on the heritage of eight different Envisat AO projects supported by national agencies and ESA in the early phases of Envisat, and working closely with the SCIAMACHY Validation and Interpretation Group (SCIAVALIG), the TASTE (2004-2008) and Multi-TASTE (after 2008) programmes have provided ESA with sustained Technical ASsistance To the long-term validation of Envisat atmospheric composition data and retrievals. The programme has been conducted by an international consortium gathering complementary expertise in atmospheric remote sensing and satellite validation, namely, BIRA-IASB (coordinator, Belgium), CNRS/LATMOS (France), FMI-ARC (Finland), IFE/IUP (Germany), FZK/KIT (Germany), INTA (Spain), KMI-IRM (Belgium), KNMI (Netherlands), NIWA (New Zealand), SPbSU (Russia), ULg (Belgium), and their NDACC collaborators. (Multi-)TASTE has ensured regular collection and delivery of ground-based correlative observations from NDACC to the Envisat Cal/Val database operated at NILU, the monitoring and verification of those fast delivery data sets, geophysical validation studies of successive versions of a list of data products from Envisat (GOMOS, MIPAS and SCIAMACHY) and Third Party Missions (SCISAT-1 ACE FTS and MAESTRO, Odin OSIRIS and SMR, GOSAT TANSO) based on comparisons with NDACC data sets, and support to the establishment of validation strategies for new and future data products. The validation studies have contributed to the maturation of retrieval algorithms undertaken by ESA’s Quality Working Groups and the SCIAMACHY Algorithm Development and Data Usage (SADDU).

As a tribute to ten years of continuous support to the maturation of Envisat and TPM atmospheric composition retrievals, this paper reports on major achievements of the TASTE and Multi-TASTE projects. It illustrates the role played by NDACC-based validations in the evolution of satellite retrieval algorithms. This paper concludes with a list of current NDACC developments and perspectives in response to the new challenges posed by the upcoming Sentinels S5p, S4 and S5 and the candidate Earth Explorer PREMIER.