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Prof. Eric W. Frew

is an Associate Professor in the Ann and H.J. Smead Aerospace Engineering Sciences Department, and Director of the Autonomous Systems Interdisciplinary Research Theme in the College of Engineering and Applies Sciences at the University of Colorado Boulder. He received his B.S. in mechanical engineering from Cornell University in 1995 and his M.S and Ph.D. in aeronautics and astronautics from Stanford University in 1996 and 2003, respectively.

Dr Frew has been designing and deploying unmanned aircraft systems for over twenty years. His research interests focus on autonomous flight of unmanned aircrafts; distributed information-gathering by mobile robots; miniature self-deploying systems; and guidance and control of unmanned aircraft in complex atmospheric environments.

Dr. Frew was co-leader of the team that performed the first-ever sampling of a severe supercell thunderstorm by an unmanned aircraft.

Project Brief:

“Targeted observation and seeding using autonomous unmanned aircraft systems”

This project pursues an innovative approach towards the enhancement of precipitation by developing and assessing an autonomous unmanned aircraft system (UAS) that utilizes in-situ real time data to sense and target suitable clouds for seeding.

Simple, calibrated and well-validated payloads designed to measure meteorological state parameters, wind, turbulence and aerosol-cloud microphysical properties in conditions conducive to seeding have been integrated into a new UAS platform.

Data assimilation algorithms and an associated observation simulation system, rapid enough to use for cloud seeding online decision-making, are also developed.

Finally, targeted observation and delivery strategies will be designed that guide the UAS towards suitable targets to implement successful seeding operations.

Research Progress:

During the project’s initial stages, the team assimilated data from previous field campaigns to identify cloud seedability conditions, begin integration of sensors into unmanned aircrafts, and create simulations to assess algorithms.

Professor Frew’s team has also focused on designing an unmanned aircraft platform, acquiring custom miniaturized versions of the sensors needed for missions, and integrating the sensors into the aircraft.


In the project’s second year, the team will conduct flight testing to evaluate the sensors and sampling strategies, including a field campaign near Boulder, Colorado to demonstrate full system capabilities.

Next steps also include further calibrating and validating the performance of the aircraft and sensors, demonstrating the autonomy algorithms and concept of operations through local flight tests, and then preparing for a field campaign in the UAE.

During the last year of the project, a one-month field campaign will be conducted in the UAE in collaboration with local scientists and UAE aviation authorities. System integration and autonomy algorithms will be completed, and the results from the campaign analyzed and disseminated.