Forecasting Obstacle-Induced Microscale Turbulence for UAM/AAM Operations in and Around Semi-Enclosed Venues

Forecasting atmospheric turbulence at the microscale (1-5 meters) is a key component for safe and effective Urban Air Mobility / Advanced Air Mobility (UAM/AAM) operations. Heterogenous urban landscapes can induce complicated turbulent regimes via interactions between winds and the structure of the surface resulting in turbulent wakes and hazardous flight conditions. The uncertainty of turbulence is particularly enhanced in urban environments with complex civil obstacles, such as near semi-enclosed sports venue or in a dense city center which are also locations where the use of UAM would greatly improve public safety, entertainment, and situational awareness.

Large Eddy Simulations (LES) are useful for resolving obstacle-aware atmospheric flow at the turbulent scales pertinent to UAM/AAM operations but have historically been too slow and computationally expensive for planning/preparation (forecasting) and have traditionally only been effective at simulating theoretical meteorologic regimes. The Joint Outdoor-indoor Large Eddy Simulation (JOULES) is a full physics, obstacle-aware, LES code that has been designed to run on a GPU system and can perform high resolution atmospheric simulations faster than real-time. Aeris has built an operational system for inline downscaling of several common NWP models (HRRR, ERA5, & WRF) to a microscale NWP forecasting service (JOULES-NWP) that can provide stakeholders with detailed turbulence forecast at meter-scale resolutions in complex urban environments. Recently, this code has been adopted to simulate obstacles at the neighborhood scale down to 1m resolution. To support this capability, a preprocessing pipeline has been designed to ingest engineering models of large venues and adapt their geometry to formats that can be simulated within JOULES NWP.

We will present several simulations using JOULES-NWP in a 2.5 km2 area surrounding the Stade de France (SdF), a central venue of the 2024 Summer Olympics in Paris. By reconstructing the SdF building design, as well as all neighboring buildings, we produced time-varying turbulent profiles for areas where UAM/AAM activity might occur. The results of our turbulence study highlight how JOULES-NWP can quantify the influence of time-varying meteorology, building design, and diurnal cycling on the probability of hazardous turbulence. We will also demonstrate how this capability can be adapted to practical implementation in a UAM/AAM UAS flight safety assessment forecast.