Ice Crystals and Visibility over Arctic Regions for Aviation Applications

The goals of this work are 1) to summarize the observations collected during two Arctic field projects called FRAM (Fog Remote Sensing and Modeling) and SAAWSO (Satellite Applications for Arctic Weather and SAR (Search And Rescue) Operations) projects that took place in the Arctic during winter of 2010-2011 and 2013-2014, respectively, and 2) to improve ice fog and light snow precipitation microphysics for operational applications. Both projects had unique ground base instruments to measure extinction, visibility, ice particle spectra, aerosol spectra, light precipitation, turbulence, and solar radiation. In addition to surface in-situ observations, remote sensing instruments such as Lidar, Ceilometer, PMWR (Profiling Microwave Radiometer), and MRR (Microwave Rain Radar) were also used for data collection. The main microphysical sensors used for ice and aerosol particle spectra in the project were the EC GCIP(Environment Canada Ground Cloud Imaging Probe), LTU ICIP (Lulea Technical University Ice crystal Imaging Probe), NCAR VIPS (Video Ice Particle Sampler, <500 micron) and replicators, TSI APC(Aerosol Particle Counter, >0.3 micron), and OPC 212-2 (MetOne Inc. Optical Particle Counter, >0.3 micron). The spectra from these sensors cover from 0.3 micron up to 1000 micron size range. A laser precipitation measurements (LPM) sensor was also used to collect the observations from 100 micron up to cm size range. In this work, the results related to extinction (as well as visibility), ice crystal spectra with sizes less than about 500 micron (usually not measured by conventional weighing gauges or optical sensors), light snow precipitation, and ice fog and light snow parameterizations for aviation applications will be discussed and future challenges will be emphasized.