Urban Heat Experiment Around Lubbock, Texas (U-HEAT): An Exploration of Urban Heat Islands and Associated Advection

Heat-related illnesses are well-documented and account for the most weather related deaths per year in the US. According to the US National Weather Service, in 2021, 375 people died of heat-related illnesses compared to the second leading cause flooding (146 deaths). Nicknamed “The Silent Killer” by NOAA, heat is typically disregarded as a danger because “it doesn’t topple trees or rip roofs off houses like tornadoes and hurricanes.” These heat-related dangers can be enhanced for cities like Lubbock (population of 260,993), located in western Texas, by the urban heat island (UHI) effect. Typically, UHI occurs when higher temperatures occur in urban areas than surrounding rural regions. During the development of the UHI, the associated increased sensible heat flux leads to an imbalance in the surface energy budget, and a reduction in latent heat fluxes resulting in soil moisture deficits which exacerbate the impacts of heat waves. Previous studies in cities ranging from Moscow, Russia to Paris, France have shown that UHII evolves with varying wind speeds and directions affecting not only city centers but also the surrounding urban-rural areas. However, little emphasis has been given to investigate these effects in smaller-sized cities. In the US, 82% of the population resides in relatively smaller-sized cities with populations between 100 and 900 thousand. Past studies have shown little—to—no regard for how urban heat island effects impact smaller cities. Heat has been shown to govern the spatial pattern of pollutants and gases that have an adverse effect on human health, especially in the summer months. The impact of UHI on convection initiation has yet to be studied in detail. Nevertheless, varying wind patterns are believed to modify the UHI via urban heat advection (UHA), impacting nearby surrounding rural areas disrupting crops and increasing heat-related illnesses, in areas that do not typically experience these effects. Within this work, we aim to study the effects of UHII variability under varying wind regimes utilizing a newly deployed localized micronet along with the existing West Texas Mesonet network in and around Lubbock (Texas), located in an arid region, for a year-long period. The Urban Heat Experiment Around Lubbock, Texas (U-HEAT) project employs temperature and humidity sensors (HOBO sensor from Onset Inc.) at 2-m above ground level at 23 stationary micronet sites, spanning across the urban core, sub-urban region and adjacent rural areas, and two sensors mounted on mobile platforms for intensive observations during nighttime hours only. Based on recent findings from mobile deployments across a 640 km² domain centered around the city, it was possible to observe up to 2°C temperature increase downwind due to UHA. In addition to these stationary sensors, overnight 2-m mobile temperature heat maps, statistics, and bulk time series’ will be analyzed and compared with output from weather forecasting models (e.g., the High Resolution Rapid Refresh or HRRR model) and satellite measurements of surface temperatures to determine the model biases for different weather conditions and also to validate satellite measurements of UHI. This work will help facilitate better forecasts of extreme heat hazard events via forecasting the most appropriate regions within and around the city and provide better information for planning outdoor events, helping the public avoid excessive heat-related hazards, heat stress, or any other heat related illness. Finally, this work will establish that smaller-sized cities also require better urban planning and risk management than is currently present.