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Relative humidity dependence of light absorption by mineral dust after long‐range atmospheric transport from the Sahara
Author(s) -
Lack Daniel A.,
Quinn Patricia K.,
Massoli Paola,
Bates Timothy S.,
Coffman Derek,
Covert David S.,
Sierau Berko,
Tucker Sara,
Baynard Tahllee,
Lovejoy Edward,
Murphy Daniel M.,
Ravishankara A. R.
Publication year - 2009
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2009gl041002
Subject(s) - relative humidity , absorption (acoustics) , mineral dust , range (aeronautics) , aerosol , humidity , atmospheric sciences , air mass (solar energy) , environmental science , analytical chemistry (journal) , materials science , chemistry , meteorology , environmental chemistry , physics , thermodynamics , boundary layer , composite material
The relative humidity (RH) dependence of light absorption for a Saharan dust‐dominated air mass transported to the Gulf of Mexico was measured during the 2006 TexAQS/GoMACCS study using a photo‐acoustic absorption spectrometer (PAS). Aerosol absorption was measured at low (25%) and high (73%) RH indicating a 1.5(±0.3) absorption enhancement [f(RH Abs )] under high RH conditions. f(RH Abs ) estimates, based on air‐mass physical and optical properties and Mie theory modeling, were between 1.2–1.4. Reasons for differences between the measured and modeled f(RH Abs ) are discussed. The mass absorption coefficient of the long‐range transported dust was calculated to be 0.04(±0.02) m 2 g −1 .