TARFOX Abstracts
at AGU Special Sessions
Baltimore, MD, 5/29-30, 1997

A41C-09
"Humidification Factors for Aerosols off the Mid-Atlantic Coast of the United States"

R.A. Kotchenruther; P. V. Hobbs; D. A. Hegg (All at: Department of Atmospheric Sciences, University of Washington, Box 351640, Seattle, WA 98195-1640, USA; ph. 1-206-543-6027; e-mail: bkotch@atmos.washington.edu, phobbs@atmos.washington.edu, deanhegg@atmos.washington.edu)

To determine direct radiative forcing by aerosols, it is necessary to know the humidification factor (HF), that is, the change in the light-scattering coefficient of the aerosol (_s) with relative humidity (RH). During TARFOX, forty-six humidographs (_s vs RH) were measured aboard the University of Washington's Convair C-131A aircraft. For RH=30% virtually 100% of the aerosol samples had HF 1.4 and 50% had HF 2.1. HF values were greater in westerly (offshore) flows than in northerly or southerly flows, and the HF generally decreased with increasing altitude and with increasing values of the ratio of carbonaceous mass to sulfate mass in the aerosol.