First MAX- DOAS results of the SO292-2 cruise across the Pacific in June/July 2022: Nouméa (New-Caledonia) to Dutch Harbor (Alaska, USA)

Transit cruises of German research vessels across oceans provide a unique platform for MAX-DOAS measurements of atmospheric trace gases such as nitrogen dioxide (NO₂), formaldehyde (HCHO) and sulphur dioxide (SO₂). The Deep Blue/PORD campaign took place from 24 June to 21 July 2022. During that period the research vessel SONNE was crossing the Pacific in meridional direction from 22° S to 54° N in an area that is typically used as reference for satellite data due to its large distance from anthropogenic emission sources.

In this study we focus on three trace gases: NO₂ columns provide information on the meridional distribution of stratospheric NO₂ as well as the distribution of tropospheric background NO₂ above the marine boundary layer. For the analysis, high signal “peaks” that only last a short time are filtered as they most likely originate from the ship exhaust. First results show a minimum of total NO₂ columns between the equator and about 15° N. HCHO and SO₂ mainly appear as plumes from nearby islands and/or volcanoes in the Solomon Sea, where biogenic and volcanic activities are naturally high. In combination with the onboard instrumentation (Ceilometer, Pyranometer and a cloud camera) this data set provides a detailed description of the atmosphere along the cruise track.