Analysis of geostationary satellite derived cloud parameters associated with high ice water content environments
Adrianus de Laat1, Eric Defer2, Julien Delanoë3, Fabien Dezitter4, Amanda Gounou5, Alice Grandin4, Anthony Guignard3, Jan Fokke Meirink1, Jean-Marc Moisselin5, and Frédéric Parol61KNMI, de Bilt, The Netherlands 2Laboratoire d'Aérology, CNRS/OMP Toulouse, France 3Laboratoire Atmosphère, Milieux et Observations Spatiales, UVSQ, Guyancourt, France 4AIRBUS, Toulouse, France 5Meteo France, Toulouse, France 6Laboratoire d'Optique Atmosphérique, Université de Lille, Sciences et Technologies, Villeneuve d'Ascq, France
Received: 27 Jul 2016 – Accepted for review: 14 Oct 2016 – Discussion started: 25 Oct 2016
Abstract. We present a newly developed high ice water content mask (High IWC) based on measurements of the cloud physical properties (CPP) algorithm applied to the geostationary Meteosat Second Generation (MSG) Spinning Enhanced Visible and Infrared Imager (SEVIRI). The mask was developed within the European High Altitude Ice Crystals (HAIC) project for detection of upper atmospheric high IWC, which can be a hazard for aviation.
Evaluation of the High IWC mask with satellite measurements of active remote sensors of cloud properties (CLOUDSAT/CALIPSO combined in the DARDAR product) shows that the High IWC mask can be fine-tuned for detection of high IWC values > 1 g/m3 in the DARDAR profiles. The best CPP predictors of High IWC were the condensed water path, cloud optical thickness, cloud phase, and cloud top height. The evaluation of the High IWC mask against DARDAR provided some indications that the MSG-CPP High IWC mask is more sensitive to cloud ice or cloud water in the upper part of the cloud, which is relevant for aviation purposes. Biases in the CPP results were also identified, in particular a solar zenith angle (SZA) dependence that reduces the performance of the High IWC mask for SZAs > 60°. Verification statistics show that for the detection of High IWC a trade-off has to be made between better detection of High IWC scenes and more false detections, i.e. scenes identified by the High IWC mask that do not contain IWC > 1 g/m3. However, the large majority of these detections still contain IWC values between 0.1–1 g/m3.
Comparison of the High IEC mask against results from the Rapid Developing Thunderstorm (RDT) algorithm applied to the same geostationary SEVIRI data showed that there are similarities and differences with the High IWC mask: the RDT algorithm is very capable of detection young/new convective cells and areas, whereas the High IWC mask appears to be better capable of detecting more mature and ageing convection as well as cirrus remnants.
The lack of detailed understanding what causes aviation hazards related to High IWC hampers further tuning of the High IWC mask. Additional evaluation of the High IWC mask against field campaign data should provide more information on the performance of the MSG-CPP High IWC mask and contribute to a better characterization.
de Laat, A., Defer, E., Delanoë, J., Dezitter, F., Gounou, A., Grandin, A., Guignard, A., Meirink, J. F., Moisselin, J.-M., and Parol, F.: Analysis of geostationary satellite derived cloud parameters associated with high ice water content environments, Atmos. Meas. Tech. Discuss., doi:10.5194/amt-2016-246, in review, 2016.