1 research outputs found
Heating Rate of Light Absorbing Aerosols: Time-Resolved Measurements, the Role of Clouds, and Source Identification
Light
absorbing aerosols (LAA) absorb sunlight and heat the atmosphere.
This work presents a novel methodology to experimentally quantify
the heating rate (HR) induced by LAA into an atmospheric layer. Multiwavelength
aerosol absorption measurements were coupled with spectral measurements
of the direct, diffuse and surface reflected radiation to obtain highly
time-resolved measurements of HR apportioned in the context of LAA
species (black carbon, BC; brown carbon, BrC; dust), sources (fossil
fuel, FF; biomass burning, BB), and as a function of cloudiness. One
year of continuous and time-resolved measurements (5 min) of HR were
performed in the Po Valley. We experimentally determined (1) the seasonal
behavior of HR (winter 1.83 ± 0.02 K day<sup>–1</sup>;
summer 1.04 ± 0.01 K day<sup>–1</sup>); (2) the daily
cycle of HR (asymmetric, with higher values in the morning than in
the afternoon); (3) the HR in different sky conditions (from 1.75
± 0.03 K day<sup>–1</sup> in clear sky to 0.43 ±
0.01 K day<sup>–1</sup> in complete overcast); (4) the apportionment
to different sources: HR<sub>FF</sub> (0.74 ± 0.01 K day<sup>–1</sup>) and HR<sub>BB</sub> (0.46 ± 0.01 K day<sup>–1</sup>); and (4) the HR of BrC (HR<sub>BrC</sub>: 0.15 ±
0.01 K day<sup>–1</sup>, 12.5 ± 0.6% of the total) and
that of BC (HR<sub>BC</sub>: 1.05 ± 0.02 K day<sup>–1</sup>; 87.5 ± 0.6% of the total)