POLar study using Aircraft, Remote sensing, surface measurements and modelling of Climate, chemistry, Aerosols and Transport (POLARCAT) "Aerosols have a large effect on radiation transmission in the Arctic troposphere, both directly and indirectly via clouds. POLARCAT will study transport to the Arctic of aerosols, as well as of air pollution more generally, from anthropogenic sources and boreal forest fires. It will address the effects of this pollution on atmospheric chemistry and climate. POLARCAT will use a large number of aircraft, a ship, a train, surface stations, as well as satellite data and numerical models. The first campaign, from 26 March - 19 April will use two aircraft based in Longyearbyen, Spitsbergen. Other campaigns in February 2008 and summer 2008 will follow with aircraft being based at various locations throughout the Arctic and in the boreal region."