Increased absorption by coarse aerosol particles over the Gangetic–Himalayan region Environmental Science Division, Argonne National Laboratory, Argonne, Illinois, USA
03 Feb 2014
Received: 25 Jun 2013 – Published in Atmos. Chem. Phys. Discuss.: 26 Jul 2013 Abstract. Each atmospheric aerosol type has distinctive light-absorption
characteristics related to its physical/chemical properties. Climate models
treat black carbon as the main light-absorbing component of carbonaceous
atmospheric aerosols, while absorption by some organic aerosols is also
considered, particularly at ultraviolet wavelengths. Most absorbing aerosols
are assumed to be < 1 μm in diameter (sub-micron). Here we
present results from a recent field study in India, primarily during the
post-monsoon season (October–November), suggesting the presence of absorbing
aerosols sized 1–10 μm. Absorption due to super-micron-sized
particles was nearly 30% greater than that due to smaller particles.
Periods of increased absorption by larger particles ranged from a week to a
month. Radiative forcing calculations under clear-sky conditions show that
super-micron particles account for nearly 44% of the total
aerosol forcing. The origin of the large aerosols is unknown, but
meteorological conditions indicate that they are of local origin. Such
economic and habitation conditions exist throughout much of the
developing world. Hence, large absorbing particles could be an important
component of the regional-scale atmospheric energy balance.
Revised: 23 Oct 2013 – Accepted: 16 Dec 2013 – Published: 03 Feb 2014
Citation: Manoharan, V. S., Kotamarthi, R., Feng, Y., and Cadeddu, M. P.: Increased absorption by coarse aerosol particles over the Gangetic–Himalayan region, Atmos. Chem. Phys., 14, 1159-1165, doi:10.5194/acp-14-1159-2014, 2014.