Effects of long-range transport and clouds on cloud condensation nuclei in the springtime Arctic

Abstract

Variations in cloud condensation nuclei (CCN) concentration vertical profiles during the First International Satellite Cloud Climatology Project (ISCCP) Regional Experiment/ Arctic Clouds Experiment (FIRE/ACE) flights over the Arctic Ocean were investigated using back trajectories and satellite photos. In contrast with CCN measurements over other oceans, concentrations over the Arctic generally increased with altitude. Although land masses did not seem to have as much of an immediate effect on concentrations over the Arctic as over other oceans, the small size of the Arctic Ocean may leave it open to greater overall continental/anthropogenic influences. Cloud scavenging seemed to be the most likely cause of decreased CCN concentrations. More efficient scavenging by liquid clouds, because of their higher concentrations and surface areas than cirrus clouds, probably accounted for decreasing concentrations at lower altitudes. Copyright 2002 by the American Geophysical Union.