Urban-Suburban Microscale Weather Simulation and Hazard Translation for UAS and AAM: Refinements and Advancements using Real-World Operational Scenarios

The Federal Aviation Administration (FAA), in collaboration with state governments, other research organizations, and industry experts, continues to engage and work to define, advance, and safeguard uncrewed aviation systems (UAS) and advanced air mobility (AAM) operations. A persistent and cross-cutting challenge, as these missions and operating domains continue to expand, mature, and diversify is identifying and mitigating impactful urban, suburban, and terrain-influenced microscale weather conditions and to help ensure safe and efficient UAS/AAM operations. It has been shown that hazardous conditions in urban and suburban environments can vary greatly given the time of day or larger-scale wind/environmental conditions which are further perturbed by the built environment. Without sufficient weather observations and forecasts at the appropriate temporal and spatial scales, assessing operating risks will continue to be a challenge for UAS/AAM missions. Enhancements and findings from this research exploring microscale weather modeling have demonstrated a path forward for not only evaluating the microscale urban and suburban weather hazard conditions, but also to allow for enhanced services that enable improved planning, training, and safeguarding that reduce weather risks, for safer, more sustainable, and scalable UAS and AAM operations.

This paper presents methods and results for utilizing a fast-time, building-resolvable, urban microscale weather model to objectively evaluate the range and sensitivity of weather (wind) conditions, and associated weather hazards, pertinent to UAS / AAM operations in a city setting. For this effort, the Joint Outdoor-indoor Urban Large Eddy Simulation (JOULES) model^[1] was applied to the suburban area and central urban core of Winston-Salem, NC. Winston-Salem (and the state of North Carolina) is a hotbed for UAS and AAM interests and early operations, and an active participant of the FAA’s UAS BEYOND effort. As such, microscale weather modeling for this domain provides opportunities to consider the needs and potential utility of advanced, high-resolution urban weather simulations from the perspectives of multiple, explicit UAS and AAM operational concepts of use and actual UAS stakeholder mission priorities. For this domain and range of active, planned, or envisioned UAS and AAM operational interests, results from executed microscale weather simulations demonstrate:

• How variability and associated potential weather challenges and hazards across a 12 x 14 km urban-suburban domain may affect actual, proposed, or representative launch / landing and 3-D trajectory locations associated with UAS and AAM operations within Winston-Salem.
• How microscale wind (turbulence) conditions across this domain may change (and become more significant and potentially challenging) across a multi-hour period when heating from the sun excites and ‘mixes’ the low-level atmosphere.
• How a mesoscale model from the National Oceanic and Atmospheric Administration (NOAA) (or elsewhere) can be ingested and downscaled to provide a forecast of urban-suburban microscale weather conditions and potential weather hazards.
• How the performance of the microscale weather model compares to localized wind observations provided by UPS-Flight Forward (UPS-FF) at their Winston-Salem operational launch/landing site.
• How ongoing development in cities that continue to grow and change (as planned in Winston-Salem), can modify and disrupt microscale weather conditions, with potential implications for established or planned UAS and AAM operations.

A key advancement by MITRE CAASD microscale weather modeling research has been the development of a derived winds/turbulence hazard translation product applicable to UAS and AAM operations. As part of this effort, this hazard product, known as Shake and Sharp^TM was further refined and corroborated, as part of this effort, by emulating and evaluating a known UAS accident scenario in an urban environment (midtown Manhattan) in the microscale weather modeling environment, and assessing the validity of UAS microscale weather hazard identification. Results of this research, along with additional, augmenting hazard translation services, informed by UAS operator needs, are also included in this paper.

NOTICE

This work was produced for the U.S. Government under Contract 693KA8-22-C-00001 and is subject to Federal Aviation Administration Acquisition Management System Clause 3.5-13, Rights In Data-General, Alt. III and Alt. IV (Oct. 1996).

The contents of this document reflect the views of the author and The MITRE Corporation and do not necessarily reflect the views of the Federal Aviation Administration (FAA) or the Department of Transportation (DOT). Neither the FAA nor the DOT makes any warranty or guarantee, expressed or implied, concerning the content or accuracy of these views.

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[1] The JOULES model is managed by Aeris LLC. The model has been extensively validated over the past 10+ years, and in 2019, MITRE completed an extensive validation of JOULES model use for UAS / AAM interests and potential applications.