BOREAS - a new MAX-DOAS profile retrieval algorithm for aerosols and trace gases

• Verfasst von: Bösch, Tim [VerfasserIn]
• Verfasst von: Lampel, Johannes [VerfasserIn]
• Verfasst von: Schmitt, Stefan [VerfasserIn]
• Titel: BOREAS - a new MAX-DOAS profile retrieval algorithm for aerosols and trace gases
• Verf.angabe: Tim Bösch, Vladimir Rozanov, Andreas Richter, Enno Peters, Alexei Rozanov, Folkard Wittrock, Alexis Merlaud, Johannes Lampel, Stefan Schmitt, Marijn de Haij, Stijn Berkhout, Bas Henzing, Arnoud Apituley, Mirjam den Hoed, Jan Vonk, Martin Tiefengraber, Moritz Müller, and John Philip Burrows
• E-Jahr: 2018
• Jahr: 21 Dec 2018
• Umfang: 27 S.
• Fussnoten: Gesehen am 06.04.2020
• Titel Quelle: Enthalten in: Atmospheric measurement techniques
• Ort Quelle: Katlenburg-Lindau : Copernicus, 2008
• Jahr Quelle: 2018
• Band/Heft Quelle: 11(2018), 12, Seite 6833-6859
• ISSN Quelle: 1867-8548
• DOI: doi:10.5194/amt-11-6833-2018
• Datenträger: Online-Ressource
• Sprache: eng
• K10plus-PPN: 1694133001

Abstract

<p><strong>Abstract.</strong> We present a new MAX-DOAS profiling algorithm for aerosols and trace gases, BOREAS, which utilizes an iterative solution method including Tikhonov regularization and the optimal estimation technique. The aerosol profile retrieval is based on a novel approach in which the absorption depth of <span class="inline-formula">O₄</span> is directly used in order to retrieve extinction coefficient profiles instead of the commonly used perturbation theory method. The retrieval of trace gases is done with the frequently used optimal estimation method but significant improvements are presented on how to deal with wrongly weighted a priori constraints and for scenarios in which the a priori profile is inaccurate.</p> <p>Performance tests are separated into two parts. First, we address the general sensitivity of the retrieval to the example of synthetic data calculated with the radiative transfer model SCIATRAN. In the second part of the study, we demonstrate BOREAS profiling accuracy by validating the results with the help of ancillary measurements carried out during the CINDI-2 campaign in Cabauw, the Netherlands, in 2016.</p> <p>The synthetic sensitivity tests indicate that the regularization between measurement and a priori constraints is insufficient when knowledge of the true state of the atmosphere is poor. We demonstrate a priori pre-scaling and extensive regularization tests as a tool for the optimization of retrieved profiles. The comparison of retrieval results with in situ, ceilometer, <span class="inline-formula">NO₂</span> lidar, sonde and long-path DOAS measurements during the CINDI-2 campaign always shows high correlations with coefficients greater than 0.75. The largest differences can be found in the morning hours, when the planetary boundary layer is not yet fully developed and the concentration of trace gases and aerosol, as a result of a low night-time boundary layer having formed, is focused in a shallow, near-surface layer.</p>