In 2019-2020 summer period, the Australian wildfires season was exceptionally intense and long. In particular, in December-January in the southeast of the country, the fires had catastrophic environmental impacts, and deteriorated air quality to hazardous levels. Moreover, intense pyrocumulonimbus (pyroCb) formation injected smoke and gases directly into the stratosphere, with likely large impacts on the atmospheric chemistry at such altitudes.
The image shows TROPOMI/Sentinel-5 Precursor observations of HONO (slant columns) over the Australian fires on January 4, 2020, overlaid on the RGB image from the VIIRS/S-NPP sensor. Nitrous acid is detected over many fires, and even extended further downwind. The measured HONO slant columns were exceptionally high, up to 2 x 1016 molec/cm².