Figure 2

SO₂ VCD detection limit (at 3-σ level) for a tropospheric plume at 3 km height, as a function of pixel size (in km²) for space nadir sensors with proven capability to detected SO₂ (values are adapted from the literature and personal communications). Pale orange points are used for thermal infrared imagers: ASTER⁴⁴, VIIRS (detection limit presumably similar as MODIS), MODIS^45,46, SEVIRI⁴⁷. In blue, the IASI^21,48 and AIRS¹⁸ thermal infrared hyperspectral sounders. Purple points are used for UV-VIS instruments: TOMS⁴⁹, GOME⁵⁰, SCIAMACHY⁵¹, GOME-2⁵², OMPS⁵³, OMI^34,53, and TROPOMI^32,33 (this study). The orange curves are the corresponding iso-lines of SO₂ mass detection limit (t/km²).