High spatial- and temporal-resolution anthropogenic heat discharge estimation in Los Angeles County, California.

Anthropogenic heat flux (Qf), which originates through energy consumption from buildings, industrial plants, vehicle exhausts, and human metabolism releases, is an important component in the urban Surface Energy Balance (SEB) system, and is key to understanding of many urban environmental issues. The present study provided a hybrid Qf modeling approach, which combined the inventory and GIS approach to create a 365-day hourly Qf profile at 120 m spatial resolution in Los Angeles County, California, USA. Qf was estimated by separate calculation of heat release from buildings, traffics, and human metabolism, respectively. The results indicated that Qf showed different magnitudes and diurnal patterns between workdays (dual-peak shape) and weekends/holidays, and also varied with seasons, and land use types. Qf yielded the highest values in the summer workdays, with its maximum value of 7.76 w/m2. Qf in hot summer workdays was obviously higher than that in the average summer workdays, which caused by higher demands for space cooling in buildings, and can reach 8.14 w/m2 at maximum. Building energy consumption was identified as the dominant contributor to the Qf in Downtown Los Angeles, which was found to have the largest mean Qf throughout the year among all neighborhoods. It can be concluded that Qf in the downtown was more significant in workdays than that in non-workdays, and its maximum value can reach 100 w/m2. It is suggested that our approach may have wider applicability for Qf estimation in large areas compared with the existing studies, as all the data used were available to the public. A high spatial and temporal Qf profile, which can readily be incorporated into urban energy balance and Urban Heat Island (UHI) studies, provides valuable data and information for pertinent government agencies and researchers.