Global temperature dependency of biogenic HCHO columns observed from
space: Interpretation of TROPOMI results using GEOS-Chem model
Abstract
Temperature is the principal driver of global HCHO and its primary
oxidation precursor biogenic volatile organic compounds (BVOCs). We
revisit such a temperature (T-) dependency globally, leveraging TROPOMI
HCHO column data. We find substantial variations in the T-dependency of
biogenic HCHO across plant functional types (PFTs), with the highest
over Broadleaf Evergreen Tropical Trees (doubling every 6.0 K ± 2.1 K)
and lowest over Arctic C3 Grass (doubling every 30.8 K ± 9.6 K). The
GEOS-Chem model interprets HCHO columns’ T-dependency at the PFT level
(r = 0.87), with a 16% discrepancy on average. The discrepancy can be
explained by BVOC emissions T-dependency for Broadleaf Evergreen
Tropical Trees and Warm C4 Grass and can be attributed to the
insensitivity of HCHO columns to BVOC emissions for other PFTs. Our
findings underscore a potentially magnified variation of BVOC emissions
by GEOS-Chem and MEGAN therein, particularly in regions experiencing
greater temperature variations.