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Volume 8, Issue 9 (Suppl)
J Earth Sci Clim Change
ISSN: 2157-7617 JESCC, an open access journal
Climate Congress 2017
October 16-17, 2017
October 16-17, 2017 Dubai, UAE
3
rd
World Congress on
Climate Change and Global Warming
Chemistry and photochemistry of tropospheric aerosols: Their role in controlling the earth albedo
Agustin J Colussi
California Institute of Technology, USA
A
erosol particles affect the earth’s energy balance directly by absorbing and scattering radiation and indirectly by altering the
reflectance and persistence of clouds. Laboratory experiments show that the absorptivity of representative aerosol organic
matter is not a single-valued function of its molecular composition CxHyOz, but markedly depends on temperature and ionic
strength, which is inversely dependent on relative humidity, and changes from dark to bright conditions (i.e., between night
and day). Suites of representative polyfunctional CxHyOz oligomers in water develop intense visible absorptions upon addition
of inert electrolytes such as ammonium bisulfate (ABS). The resulting mixtures reach mass absorption cross sections (532 nm)
~0.1 m
2
/gC in a few hours, absorb up to 9 times more solar radiation than the starting material, can be half-bleached by sunlight
in ~1 hour at noon and repeatedly recycled without carbon loss. Visible absorptions red-shift and evolve increasingly faster in
subsequent thermal aging cycles. These transformations are deemed to underlie the daily cycles of aerosol absorption observed
in the field, which introduce critical feedbacks in the Earth’s radioactive balance. These phenomena and their timescales are
consistent with the diel cycles of aerosol scattering and absorption observed over Mexico City at constant total carbon (15.5)
gm
-3
loadings. Aerosol absorptivity peaks early in the morning and reaches minimum values.
ajcoluss@caltech.eduJ Earth Sci Clim Change 2017, 8:9 (Suppl)
DOI: 10.4172/2157-7617-C1-034