Characteristics of Ice Nucleating Particles from the Long-Range
Transport of Saharan Dust
Abstract
Transported mineral dust in a Saharan air layer (SAL) contains highly
active ice-nucleating particles (INPs) that may be transported across
the Atlantic Ocean and subsequently seed clouds in the Caribbean and the
Americas. During an aircraft campaign around Houston and the western
U.S. Gulf Coast, a widespread SAL advected into the sampling region
allowing for measurement of the ice-nucleating ability of SD following
long-range transport. Results showed that the mean INP concentrations
were 3–4.5 times higher than non-Saharan dust (nSD), but only at
temperatures < –21 ºC. Active surface site densities were
also enhanced in the SD, exceeding the mean for nSD by over an order of
magnitude at temperatures < –21 ºC. These INP measurements
confirmed that SD remains a highly active INP even after >
8000 km westward transport across the Atlantic Ocean.