Urban Microscale Weather Modeling for Climate Change and Advancing Urbanization Resiliency and Sustainability

Increased urbanization combined with ongoing climate change creates outsized resiliency risks to cities and urban centers, where most people live and work. The combinatory risks and potential impacts from both are poorly understood. These risks have not been comprehensively studied at the proper scale: the meter or microscale within and throughout individual cities, at street-by-street resolution.

The MITRE Corporation, in collaboration with Aeris LLC, has been conducting microscale weather, climate, and urbanization research that provides objective assessments of intracity risks and resiliency vulnerabilities impacting public health, energy needs and abilities for cities to achieve carbon neutrality, to advance urban air mobility and transportation, and to empower equity and environmental justice. Specifically, the research and associated experiments seek to evaluate how potential health risks (i.e., heat stress), building energy needs, and urban air mobility feasibility may change, within and throughout a city, given (a) the present climate versus modeled climate conditions in 2050, (b) the present urban landscape and land-use versus how it may evolve decades from now, and (c) changes to both climate and urban land-use and development.

Using a validated, fast-time, building-resolving Graphics Processing Unit (GPU)-resident, Large Eddy Simulation (LES) atmospheric model (JOULES[1]), experiments were designed to model climate scenarios across urban landscapes for varying initial climatological conditions, urban footprints (buildings) and large-scale weather scenarios (e.g., wind speed and direction across the city). Urban climate microscale simulations have been completed for New York City (Harlem and South Bronx), Raleigh, North Carolina, and Miami, Florida. The extended urban core of each city was modeled at a 3-meter horizontal and vertical resolution, and simulated microscale weather data (temperature, dewpoint, winds) were translated to derived metrics more meaningful to impact and implication assessments pertaining to public health, energy efficiency and potential future urban air transportation. These derived metrics and their variability across each city and for different states of urban development and climate were then assessed to understand potential intracity vulnerabilities and/or opportunities to improve resiliency as the city and its climate evolves.

Simulation results for each experiment demonstrate expected increases in temperature, heat index, and quantified building energy needs in each city due to climate change. However, city-wide simulations at the microscale further demonstrate how the specific range, severity, and location of most impactful conditions varied substantially for specific neighborhoods, buildings, schools, hospitals, and/or parks or outdoor venues depending on urban development and larger scale environmental conditions (e.g., wind flow into the city). Moreover, simulation results depict the potential value in strategic urban design that emphasizes intracity ventilation corridors, especially when able to transport relatively cooler conditions from nearby rivers, ocean, or even dense vegetation into populated and developed areas of the built environment of the city.

Results of this research will be presented, along with the implications of using microscale meteorological modeling to assess the moisture and thermal flux properties of a warming urban environment, as well as the development and application of a hyperlocal weather awareness, alerting, and planning model and web-based service that may contribute to improved heat stress safety and enhance urban resiliency within and across dense urban areas.

[1] JOULES: Joint Outdoor-indoor Urban Large Eddy Simulation

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