Visualizing the urban heat and the influence of newly constructed areas in King County, WA

Urban heat island (UHI) effects, driven by rapid urbanization, have become a critical environmental issue, particularly in growing metropolitan regions such as King County, Washington. The intensification of land surface temperatures (LST) in urban areas can exacerbate discomfort for residents, increase energy demand, and contribute to broader climate challenges. This study leverages Google Earth Engine (GEE) to analyze temporal shifts in LST over the past decade, specifically examining the relationship between newly constructed areas and urban heat in King County. Data Sources and Methodology This study uses high-resolution satellite imagery from the Landsat 8 Collection 2 Level 2 Surface Temperature dataset, which provides consistent LST data through the thermal infrared (TIR) band. Landsat 8 offers historical data spanning back to 2013, enabling a robust temporal analysis of urban heat patterns. A cloud-masking technique is applied to ensure data quality, removing pixels with high cloud confidence that could distort LST readings. The LST data are converted from Kelvin to Celsius to facilitate comparison across time periods. The following regions within King County are the focus of this analysis due to their rapid urban development: West Seattle: A region undergoing significant infrastructure expansion, including new residential areas and the West Seattle Bridge reconstruction, which has altered land use and thermal dynamics. Light Rail North Extension: With the expansion of Seattle’s light rail system, neighborhoods in the northern corridor have seen increased population density and commercial growth, contributing to local heat effects. Bellevue: Once a suburban hub, Bellevue has evolved into a central business district with substantial residential and commercial developments that may have intensified UHI effects. Issaquah: As one of Seattle’s expanding satellite towns, Issaquah has seen significant growth in housing and commercial spaces, prompting a need to assess its contributions to rising regional temperatures. Lynnwood: Positioned north of Seattle, Lynnwood has experienced rapid suburban sprawl, with new residential complexes and commercial centers influencing local LST dynamics.