Retrieving cloud optical depth and ice particle size using thermal and Far infrered radiometry in an Arctic environment

An important goal, within the context of improving climate change modelling, is to enhance our understanding of aerosols and their radiative effects (notably their indirect impacts as cloud condensation nuclei). Ice-crystal size and cloud optical depth (COD) are two key parameters whose variation strongly influences radiative effects in the Arctic environment. The presence, for example, of sulfuric-acid bearing aerosols can significantly change ice-particle size formation leading to cooling the low troposphere during the Polar-winter. The objective of this research is to retrieve ice particle size and COD using infrared radiometry. In this communication we will define a candidate retrieval algorithm and present some preliminary retrievals applied to ground-based thermal infrared (TIR) data acquired at the PEARL, high-Arctic site at Eureka, Nunavut, Canada (80°N). We also show that Far infrared radiometry (FIR) from satellite can improve the detection and analysis of ice clouds in the Arctic.