Aerial Light Detection and Ranging System for Land-Atmosphere Interaction Research

Urban areas are experiencing a rapid growth and will house nearly 68% of the world's population by the year 2050, which means that our current urban population will double in a very short time. Urban dwellers face challenges related to health risks from pollution and heat, and urban areas are notoriously vulnerable to natural hazards, with marginalized neighborhoods often bearing the brunt of the burden. To ensure a safe and healthy future for the human population, it has hence become more important than ever to design and build cities that are sustainable and equitable in their use of resources and resilient to extreme weather events. Urban planners and policy makers make use of results from numerical models to inform their decisions, but our current understanding and modeling capabilities of microscale atmospheric processes in urban environments, i.e. processes that directly affect the human population and that are characterized by a spatial scale < 1 km, lag significantly behind actual needs. Recent advances in computational fluids models and in light detection and ranging (Lidar) technology offer a promising pathway to address this knowledge gap. To expand our research infrastructure and enable new research aimed at advancing the current understanding and capability to model microscale processes in urban environments, we propose to purchase a Lidar system mounted on an unmanned aerial vehicle (UAV). The integrated instrument will be able to accurately measure built and natural environments down to a spatial resolution of few centimeters, over areas that span tens of square kilometers. A unique feature of the instrument includes the possibility to obtain waveform returns, which are critical for the accurate threedimensional reconstruction of vegetation. The UAV-based Lidar system will enable and support transformative research advances in the field of microscale land-atmosphere interaction, with research activities primarily focusing on challenges related to urban sustainability and resilience. Specifically, the instrument will be initially used to support research that synergistically integrates measurements and simulations via uncertainty quantification techniques, with the goal of quantifying how inherently uncertain tree geometries affect local and aggregate momentum exchanges between urban environments and the atmosphere. These fluxes modulate local weather in cities and their aggregate effect can influence large-scale weather patterns. In the long term, the instrument will enable research aimed at developing microscale parameterizations that account for uncertainties in surface information and efficiently and accurately propagate these to quantities of interest. Results from this project would be of substantial value to the Army. Foremost, an accurate characterization of surface properties and how they impact momentum fluxes in urban areas is critical for urban weather forecasting, which military operations routinely rely on. It is also critical for the accurate prediction of localized extreme weather conditions, which might influence soldiersÕ ability to efficiently and safely conduct terrestrial- or drone-related operations. Furthermore, the proposed UAV-based Lidar surface reconstruction and UQ methodologies represent useful technologies for the accurate characterization of urban and natural environments, which can well serve soldiers in the planning of terrestrial operations. the enabled research also has a broad applicability to many civilian interests, as it will contribute towards the development of more accurate urban microscale parameterizations, which urban planners can then make use of to design and build cities that are sustainable and equitable in their use of resources and resilient to extreme weather events.