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Modeling the Spatiotemporal Distribution and Meteorological Impacts of Anthropogenic Heat in Los Angeles

Presentation Date
Tuesday, December 12, 2023 at 10:35am - Tuesday, December 12, 2023 at 10:50am
MC - 3020 - West



Anthropogenic heat (AH) is waste heat generated by human activities. AH can impact local to regional meteorology, potentially exacerbating the urban heat island (UHI) effect. With compounded impacts of climate change and the UHI effect expected to increase in the future, it is urgent to investigate mechanisms driving urban heat and practical mitigation options. In this study, we (1) quantify the spatiotemporal distribution of AH in Los Angeles (LA), and then (2) conduct regional weather simulations to estimate the potential heat mitigation benefit of reducing AH. First, we developed a high-resolution (100 x 100 m) hourly, gridded dataset of AH flux (AHF) for LA County using a hybrid GIS-top-down approach, incorporating a variety of energy-use and geospatial datasets that characterize AH from buildings, transportation, industrial activities, and human metabolism. We find highly heterogenous spatiotemporal distributions of AHF in LA County, which is consistent with the diverse land use and energy consumption patterns across the region. The mean AHF for LA County peaks at ~3 W m-2 during summer, but the City of LA (which is a subset of the county) has a much higher maximum mean AHF of ~10 W m-2. When we disaggregate to the neighborhood scale, we find that mean AHF in the top five neighborhoods in LA county exceed 40 W m-2, while mean AHF in the bottom five neighborhoods remain below 0.15 W m-2. This implies a wide disparity of AHF impacts between neighborhoods, driven by stark differences in energy use density across LA. Individual grid pixels exceed 2,000 W m-2 in the most extreme cases. To investigate the meteorological impacts of AHF, we ran week-long simulations for representative summer and winter weeks in 2016, using the Weather Research and Forecasting (WRF) model. Mean 2 m air temperature increased up to 0.2 and 0.4 °C for summer and winter, respectively. Mean planetary boundary layer height increased up to 10 and 40 m for summer and winter, respectively. Finally, mean wind speed increased up for 0.14 m s-1 for summer, while the winter impacts on wind speed were more ambiguous. Furthermore, we estimate how future energy-use scenarios based on projected electrification of the building and transportation sectors will alter AHF distributions, and quantify potential heat mitigation co-benefits of electrification.

Funding Program Area(s)