Assessment of the 11 November 2003 AIRS-II icing event by CIP

On 11 November 2003, clouds and precipitation with widely varying character passed over the Second Alliance Icing Research Study (AIRS-II) field project. The conditions were sampled by several research aircraft and found to range from completely glaciated in the morning to water dominated by late afternoon, with a strong transitional period in between. Supercooled large drops (SLD) and icing conditions ranging from “null” to “moderate-to-severe” were encountered over Montreal's Mirabel airport during the course of the day's flight operations. This case provided a unique set of challenges for automated icing diagnosis and forecast techniques, including the differentiation of a broad spectrum of icing conditions. In this paper, output from the experimental version of NCAR's Current Icing Potential (CIP) algorithm will be assessed for all portions of the case, noting strengths and shortcomings of the CIP technique. Fields to be discussed will include icing potential, SLD potential, icing severity and cloud altitudes, including layers.