Dissipation of Mixed-Phase Arctic Clouds and Its Relationship to Aerosol Properties
Authors
Adele Igel — University of California, Davis
Joseph Sedlar — CIRES University of Colorado and NOAA Global Monitoring Laboratory
Category
High-latitude clouds and aerosols
Description
Surface aerosol concentrations in the Arctic can reach extremely low values, perhaps low enough that low-level mixed-phase stratocumulus clouds cannot be sustained. Nonetheless, these clouds are persistent features of the Arctic boundary layer and have a profound impact on the local surface energy budget, which in turn has implications for seasonal ice melt and climate change. When these low-level clouds do dissipate, it is unclear if the dissipation is linked to the aerosol concentrations, and if it is not, then how these clouds sustain themselves in the face of extremely low aerosol concentrations. One possibility is that surface aerosol concentrations are not representative of the aerosol concentrations impacting the cloud layer. Little is known about how aerosol properties vary with height in the region and how aerosol populations both below and above the clouds impact the cloud properties. We had identified possible cases of Arctic cloud dissipation from observations at the ARM NSA site and begun large eddy simulations based on these cases. The simulations are designed to test the relative importance of aerosol sources above and below the cloud layer. We have also been working to use the in situ lidar data at the site to characterize the aerosol properties within and above the boundary layer. The current status of these efforts will be discussed.
