Climatology of the icing potential and events of freezing over the Colombian continental territory

Abstract:

Icing has been linked as the cause of several air accidents in Colombia. Icing in aviation occurs when water droplets overcooled in the atmosphere freeze and create an ice sheet on the outside of aircraft reducing their aerodynamic lift and instrument damage. Due to lack of observations and research campaigns, Colombia has not had frequency information and space-time distribution of the freezing potential (ICEPOT), and there is also no evidence of methods for diagnosing, monitoring and forecasting freezing on Colombian territory.In this study, the climatology of ICEPOT was estimated by the implementation of two algorithms: Current Icing Product Sonde (CIP-SONDE; Bernstein et al., 2007)) and Supercooled Liquid Water Simulation. METAR observations and radiosonding as well as the European Centre for Medium-Weather Forecast (ECMWF) ERA-5 reanalysis were used for the climatology calculation. Tests were carried out to find which algorithm more efficiently detects events recorded on board aircraft. Eight case studies were also analyzed using reports and aircraft data, through observations that contribute to the detection of the phenomenon, four cases "with report" and four "no report" of freezing. For these cases the WRF model and the two icing potential algorithms were used. The results show that ICEPOT follows the space-time climate patterns associated with the annual rain cycle, while the daytime cycle showed that ICEPOT tends to be higher in the evening and early hours. Overall, the results showed that CIP-SONDE algorithm was better matched to aircraft reports and produced better forecasts when used for the case studies analyzed.