The Infrared Radiative Impact of Antarctic Clouds

Northwest Research Associates, Incorporated, Seattle WA

Investigators

Abstract

Despite their importance to radiative transfer, the amount of supercooled liquid water in polar clouds may be uncertain. This underestimation in turn results in significant radiation biases at the surface and TOA (top of the atmosphere) and misrepresentation of polar aerosol-cloud interactions. Recent work involving tuning a climate model to match mixed phase cloud distributions with observations resulted in an increase in net cloud radiative effects over Antarctica. A crucial component of understanding Antarctic climate, therefore, is a more accurate representation of the abundance of supercooled liquid in clouds and of corresponding cloud-radiative interactions. Leveraging down-welling radiance measurement data previously collected with FT-IR instruments (Atmospheric Emitted Radiance Interferometers; AERIs) at South Pole Station - (2000) , Dome C - (2003) and to be made at McMurdo Station (planned for Nov. 2015-Nov. 2016) will be used to assess the seasonal dependence of cloud properties and cloud impacts on the local surface radiative budget. Two hypotheses will be considered: 1) The Antarctic radiation budget is highly sensitive to cloud properties, particularly thermodynamic phase. 2) The radiative impact of supercooled liquid in Antarctic clouds is significantly influenced by the temperature dependence of the complex refractive index of water (CRI)