New observations of NO<sub>2</sub> in the upper troposphere from TROPOMI

Abstract. Nitrogen oxides (NOx?NO+NO2) in the NOx-limited upper troposphere (UT) are long-lived and so have a large influence on oxidizing capacity of formation greenhouse gas ozone. Models misrepresent NOx UT, observations to address deficiencies models sparse. Here we obtain year near-global seasonal mean mixing ratios NO2 UT (450–180 hPa) at 1?×1? by applying cloud-slicing partial columns from TROPOMI. This follows refinement algorithm with synthetic GEOS-Chem chemical transport model. TROPOMI, prior cloud-slicing, is corrected for 13 % underestimate stratospheric variance 50 overestimate free-tropospheric determined comparison Pandora total high-altitude sites Mauna Loa, Izaña, Altzomoni MAX-DOAS tropospheric Izaña. Two cloud-sliced products June 2019 May 2020 retrieved TROPOMI using distinct cloud that assume clouds reflective boundaries (FRESCO-S) or water droplet layers (ROCINN-CAL). typically ranges 20–30 pptv over remote oceans >80 locations intense lightning. Spatial coverage mostly tropics subtropics FRESCO-S extends midlatitudes polar regions ROCINN-CAL, due its greater abundance optically thick wider cloud-top altitude range. means spatially consistent (R=0.6–0.8) an existing coarser spatial resolution (5? latitude × 8? longitude) product Ozone Monitoring Instrument (OMI). 12–26 more than OMI increase pressure ceiling (280 (180 hPa), but possibly also differences retrieval algorithms. The offers potential evaluate improve representation supplement aircraft sporadic susceptible biases UT.