The Wintertime Environment (PN-WE)

Principal Participants: Duck, Sica; Stakeholders: Servranckx, Freemantle, Garand, Gong, Strawbridge; Canadian Gov't Departments: EC,CSA; International Orgs: AERONET, NOAA, NASA; HQP: 100% RA + 1 graduate student.

Rationale The objective of this project is to understand the special role that the very stable surface-based temperature inversion plays in shaping the nature of all tropospheric processes including radiative transfer in the winter Arctic (Curry et al., 1996). This includes its role in explaining Arctic Amplification with the trapping of heat near the surface, the transport of aerosols and pollution from the free troposphere to the surface, the movement of water vapour and its transformation to clouds and precipitation. The proposed work continues what was started but not completed in the CANDAC research program which revealed new and interesting processes associated with the surface energy balance (Lesins et al., 2012), the nature of diamond dust events (Lesins et al., 2009), the role of water vapour intrusions from the south (Doyle et al., 2011) and the behavior of the aerosols and cloud ice under extreme cold (Bourdages, et al., 2009).

The conditions under which inversion layers are sustained are still not well understood given the general lack of winter observations. It is also unclear what impact ongoing climate change is going to have on surface inversion layers: whether they continue to trap heat near the ground, or disappear and allow heat to be ventilated from the surface to the free troposphere. Although the dynamical coupling between the boundary layer and the free troposphere is weak, there is still strong radiative coupling that shapes the evolution of the lapse rates. Understanding this problem will require a comprehensive view of atmospheric climate processes and especially radiative transfer and dynamics that include the effects of clouds and water vapour.