Ground-based validation of the MetOp-A and MetOp-B GOME-2 OClO measurements

• Published in: Atmospheric Measurement Techniques
• Main Authors: G. Pinardi, M. Van Roozendael, F. Hendrick, A. Richter, P. Valks, R. Alwarda, K. Bognar, U. Frieß, J. Granville, M. Gu, P. Johnston, C. Prados-Roman, R. Querel, K. Strong, T. Wagner, F. Wittrock, M. Yela Gonzalez
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2022
• Subjects: Environmental engineering; TA170-171; Earthwork. Foundations; TA715-787; Antarctic; Arctic; Antarc*
• Online Access: https://doi.org/10.5194/amt-15-3439-2022; https://doaj.org/article/3bda9ac1f4ce4934b70cc7fe8a39d213

This paper reports on ground-based validation of the atmospheric OClO data record produced within the framework of EUMETSAT's Satellite Application Facility on Atmospheric Chemistry Monitoring (AC SAF) using the Global Ozone Monitoring Experiment (GOME)-2A and GOME-2B instrument measurements, covering the 2007–2016 and 2013–2016 periods, respectively. OClO slant column densities are compared to correlative measurements collected from nine Zenith-Scattered-Light Differential Optical Absorption Spectroscopy (ZSL-DOAS) instruments from the Network for the Detection of Atmospheric Composition Change (NDACC) distributed in both the Arctic and Antarctic. Sensitivity tests are performed on the ground-based data to estimate the impact of the different OClO DOAS analysis settings. On this basis, we infer systematic uncertainties of about 25 % (i.e., about 3.75×10 13 molec. cm −2 ) between the different ground-based data analyses, reaching total uncertainties ranging from about 26 % to 33 % for the different stations (i.e., around 4 to 5×10 13 molec. cm −2 ). Time series at the different sites show good agreement between satellite and ground-based data for both the inter-annual variability and the overall OClO seasonal behavior. GOME-2A results are found to be noisier than those of GOME-2B, especially after 2011, probably due to instrumental degradation effects. Daily linear regression analysis for OClO-activated periods yield correlation coefficients of 0.8 for GOME-2A and 0.87 for GOME-2B, with slopes with respect to the ground-based data ensemble of 0.64 and 0.72, respectively. Satellite minus ground-based offsets are within 8×10 13 molec. cm −2 , with some differences between GOME-2A and GOME-2B depending on the station. Overall, considering all the stations, a median offset of about <math xmlns="http://www.w3.org/1998/Math/MathML" id="M9" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>-</mo><mn mathvariant="normal">2.2</mn><mo>×</mo><msup><mn ...