Overview of Cloud Microphysical Measurements during the SENS4ICE Airborne Test Campaigns: Contrasting Icing Frequencies from Climatological Data to First Results from Airborne Observations

Abstract

<div class="section abstract"><div class="htmlview paragraph">The European Union’s Horizon 2020 programme has funded the SENS4ICE (Sensors for Certifiable Hybrid Architectures for Safer Aviation in Icing Environment) project [<span class="xref">1</span>], an innovative approach for the development and testing of new sensors for the detection of supercooled large droplets (SLD). SLD may impinge behind the protected surfaces of aircraft and therefore represents a threat to aviation safety. The newly developed sensors will be tested in combination with an indirect detection method on two aircraft, in two parallel flight programs: One on the Embraer Phenom 300 in the U.S. and one on the ATR-42 in Europe.</div><div class="htmlview paragraph">In this framework the Deutsches Zentrum für Luft- und Raumfahrt (German Aerospace Center) is in charge of the airborne measurements and data evaluation of the microphysical properties of clouds encountered during the SENS4ICE field campaigns in February, March and April 2023. We present the instrumentation that is used in the flight experiments for the characterization of icing environments and for the validation and performance assessment of new sensors for the detection and discrimination of Appendix O and Appendix C conditions [<span class="xref">2</span>, <span class="xref">3</span>].</div><div class="htmlview paragraph">Further, with partners from Centre Europeen De Recherche Et De Formation Avancee En Calcul Scientifique (CERFACS), the German Weather Service (DWD), the Italian Aerospace Research Center (CIRA) and Leading Edge Atmospherics (LEA), we present the considerations that were undertaken to find the best campaign location with highest frequency of icing occurrence on a climatological basis, taking into account the safety requirements of the aircraft. Four data sets of icing conditions based on various meteorological input data (model and observations) have been analyzed to provide an overview of the occurrence of icing. The data give a good impression on the geographical and vertical distribution of icing conditions above Europe and the Northern U.S. in general and specifically at higher altitudes (&gt; 750 hPa or 8000ft) for the European campaign. We find enhanced icing frequencies between 1 to 5% at altitudes between 2 and 6 km even in the spring, summer and autumn months above Europe.</div><div class="htmlview paragraph">We show highlights from selected individual cases from the North American test campaign performed in February and March 2023. The analysis gives a first impression of the extensive data set of icing conditions made available by the SENS4ICE project for sensor evaluation and for validation of satellite observations and model forecasts.</div></div>