Relative humidity dependence of light absorption by mineral dust afterlong-range atmospheric transport from the Sahara

摘要

The relative humidity (RH) dependence of lightabsorption for a Saharan dust-dominated air masstransported to the Gulf of Mexico was measured duringthe 2006 TexAQS/GoMACCS study using a photo-acousticabsorption spectrometer (PAS). Aerosol absorption wasmeasured at low (25%) and high (73%) RH indicating a1.5(±0.3) absorption enhancement [f(RHAbs)] under highRH conditions. f(RH_(Abs) estimates, based on air-mass Abs physical and optical properties and Mie theory modeling,were between 1.2-1.4. Reasons for differences between themeasured and modeled f(RHAbS) are discussed.