Characterizing the contribution of summer aerosol to cloud formation in the Canadian Arctic

Arctic aerosols undergo a strong seasonal cycle, with higher aerosol mass in the winter and spring from pollution transported from southerly latitudes, and much lower aerosol mass in the summer when wet deposition removes these aerosols from the atmosphere before they can reach the Arctic. The radiation budget in the summer is extremely important since it contributes to surface warming, so the effect of aerosols on cloud properties in summer must be characterized. The clean periods in the summer can affect radiation in two ways: they can lead to new particle formation (NPF) events, followed by particle growth that allow the particles to become active as cloud condensation nuclei (CCN) at moderate supersaturations (