The air we breathed; the climatology of a 12, 000 kilometre cruise through the North Atlantic.

Aerosols have a large effect on radiation transmission in the Arctic troposphere, both directly and indirectly via clouds. The spring IPY POLARCAT project coordinated numerous projects to study transport to the Arctic of aerosols, as well as of air pollution more generally from anthropogenic sources. The NOAA International Chemistry Experiment in the Arctic Lower Troposphere (ICEALOT) cruise was conducted aboard the R/V Knorr in the North Atlantic Ocean and the Greenland, Norwegian, and Barents Seas from 41-80 degrees N during March and April of 2008. During the cruise we encountered air masses from a variety of sources including fresh continental outflow, aged plumes, pristine Arctic air pristine Arctic air, marine vessel emissions, and coastal point sources. Results from lagrangian particle dispersion modelling and synoptic meteorological analysis will be described to present a picture of the air we breathed.