This activity brings together key scientists from the different satellite missions and in situ measurement experts, as well as theoreticians and modelers to address current key questions related to PSCs. The main objectives are to: assess recent research developments, compare remote and in situ datasets to identify their strengths and limitations, identify the key PSC characteristics required by global models and available from measurements, synthesize the new datasets into a state of the art PSC climatology, and identify remaining open science questions. This activity will ultimately lead to improved representation of PSC processes in global climate models.