Volatile organic compounds: Emissions as constrained by satellite observations and global production of secondary organic aerosols via dicarbonyl formation.

摘要

This thesis quantitatively improves the current understanding of nonmethane volatile organic compound (NMVOC) emissions, as well as the global effect of these emissions on secondary organic aerosol (SOA) production via glyoxal and methylglyoxal formation.;I use GOME satellite measurements of formaldehyde (HCHO) columns over east and south Asia to improve regional emission estimates of reactive NMVOCs. Mean HCHO observations are compared to simulated HCHO columns from the GEOS-Chem chemical transport model using state-of-science emission inventories. Wintertime GOME observations indicate a Chinese anthropogenic reactive NMVOC emission 25% higher than current inventories. The biomass burning source for east and south Asia is almost 5 times the estimate of current inventories. GOME reveals a large source from agricultural burning in the North China Plain in June, due to in-field burning of crop residues. Biogenic isoprene emission in east and south Asia derived from GOME is 56 +/- 30 Tg y-1. Surface ozone increases by 5 to 20 ppb in GEOS-Chem for central and northern China when using GOME-derived versus bottom-up emissions.;I construct global budgets of atmospheric glyoxal and methylglyoxal with the goal of quantifying their potential for global SOA formation via irreversible uptake. I conduct an explicit simulation of glyoxal and methylglyoxal in GEOS-Chem including our best knowledge of source sink processes. Global production of glyoxal and methylglyoxal is 45 Tg y-1) and 140 Tg y -1, respectively. Oxidation of biogenic isoprene contributes globally 47% of glyoxal and 79% of methylglyoxal. The second most important precursors are acetylene (glyoxal) and acetone (methylglyoxal), which have long lifetimes and thus maintain background concentrations. Atmospheric lifetimes of glyoxal and methylglyoxal in the model are 2.9 hours and 1.6 hours, respectively, mainly determined by photolysis. The global source of SOA from the irreversible uptake of dicarbonyls in GEOS-Chem is 11 Tg C y-1, including 2.6 Tg y-1 from glyoxal and 8 Tg C y-1 from methylglyoxal; 90% of the irreversible uptake takes place in clouds. The magnitude of this source is comparable to that of the global SOA source computed in GEOS-Chem from the reversible partitioning of the oxidation products of monoterpenes, sesquiterpenes, isoprene, and aromatics.