Seasonality

Geology

Meteorology

Environmental chemistry

Mathematics

Atmospheric sciences

Climatology

Geography

Physical chemistry

Sulfate

Environmental science

Aerosol

Thermodynamics

Mass concentration (chemistry)

Organic chemistry

Statistics

Monsoon

Chemical composition

Chemistry

Particulates

Boundary layer

Physics

Air mass (solar energy)

Nitrate

Atmospheric chemistry and physics

. Delhi, India, routinely experiences some of the world's highest urban particulate matter concentrations. We established the Delhi Aerosol Supersite study to provide long-term characterization of the ambient submicron aerosol composition in Delhi. Here we report on 1.25 years of highly time-resolved speciated submicron particulate matter (PM1) data, including black carbon (BC) and nonrefractory PM1 (NR-PM1), which we combine to develop a composition-based estimate of PM1 (“C-PM1” = BC + NR-PM1) concentrations. We observed marked seasonal and diurnal variability in the concentration and composition of PM1 owing to the interactions of sources and atmospheric processes. Winter was the most polluted period of the year, with average C-PM1 mass concentrations of ∼210 µg m−3. The monsoon was hot and rainy, consequently making it the least polluted (C-PM1 ∼50 µg m−3) period. Organics constituted more than half of the C-PM1 for all seasons and times of day. While ammonium, chloride, and nitrate each were ∼10 % of the...

Submicron aerosol composition in the world's most polluted megacity: the Delhi Aerosol Supersite study