Why HCHO matters
Formaldehyde (HCHO) is an oxidation product of nearly every volatile organic compound (VOC). Sentinel-5P TROPOMI retrieves the daily tropospheric column at 5.5 × 3.5 km.
Because HCHO has a half-life of just ~hours, a column anomaly is almost always recent and local. That makes it the cleanest precursor signal for:
- Stubble burning fronts (Oct–Nov, Apr–May)
- Refinery flares & petrochem upsets
- Forest-fire smoke transport
- Urban biogenic + traffic VOC build-up
AURA fuses HCHO with NO₂ and AOD to attribute a hotspot to combustion vs dust vs industrial source.