Recent Developments of Supercooled Liquid Water and Mixed Phase Cloud Detection from an Airborne Platform

RHS Consulting operates a cloud seeding aircraft equipped with a side looking Mini Micro Pulse LIDAR (Hexagon) and narrow beam G-band Radiometer (Radiometrics) to remotely detect supercooled liquid water (SLW) and mixed phase conditions in winter storms. This aircraft provides a unique platform for observing area-wide supercooled liquid water applicable to icing detection and avoidance as it relates to aircraft safety, validation of high resolution forecast models and cloud seeding opportunity recognition. This powerful combination offers the potential for making major advances in these areas because real time measurements are no longer constrained to thin ribbons of the sky that an aircraft has passed. This airplane routinely flies in icing conditions collecting data from each of these systems to investigate and evaluate instrument performance.

Recent data from these flights shows that micro pulse lidar measurements by themselves are sensitive to supercooled liquid and mixed phase clouds at distances up to 10 km and offer the advantage of direct range observations that do not require ancillary data sets to generate cloud liquid water contents. They also offer high potential to directly measure hydrometeor particle size distributions. Thus, the micro pulsed LIDAR technique offers great potential for providing a small low-cost solution for detecting icing hazards in supercooled liquid water and mixed phase clouds at distances up to 10km or more. Signal processing and continued development of specialized algorithms are key to correctly identifying supercooled liquid water or mixed phase conditions.

Likewise, airborne radiometer measurements have the capability to detect SLW at much greater distances in optically thick clouds. When coupled with ancillary data sets radiometers offer the advantage of producing long range observations of liquid water contents in large complex cloud systems. These measurements can identify SLW long before an aircraft encounters icing and provide data to improve accuracy in understanding what is happening in real-time at longer ranges and time scales.

Used together, the combination of these instruments significantly improves accuracy in measuring cloud characteristics and identifying icing potential. This presentation will provide an overview of the aircraft, sensors and measurements from the latest flights.