Considering Heatwaves Spatial Properties for Improving Local Adaption and Mitigation Strategies

Heatwaves increase mortality and morbidity rates and elevate demands for water and energy. Urban populations experience more frequent, longer, and more severe heatwaves due to Urban Heat Island (UHI) effect. Thus, continued global warming and urbanization increase heatwave occurrence and raise public health and urban management concerns. Accordingly, many cities prepare local response plans to address urban residents' vulnerabilities to heatwaves. Achieving the desired outcome requires understanding population vulnerability, available resources, and heatwave properties. Traditionally, urban managers and policymakers consider population vulnerability and resource availability in the neighborhood scale, while heatwaves are assumed to be evenly distributed across the region. However, recent developments in gridded meteorological data analytics indicate significant differences among local heatwaves properties.

We used Livneh dataset at 1/16-degree resolution (6 km X 6 km grid cells) for the period 1950 to 2010 to determine heatwave properties in Baltimore, MD, Bismarck, ND, Colorado Springs, CO, Dallas, TX, Des Moines, IA, Miami, FL, New York, NY, Phoenix, AZ, Portland, OR, and Syracuse, NY. We defined a heatwave in each grid cell as a period during which minimum and maximum daily temperatures exceed the 90^th percentile of the historical records of that grid cell for at least two consecutive days. Accordingly, we captured the neighborhoods with the most frequent and severe, earlier, and extended period of heatwave occurrences.

For example, we found that on average, the first heatwave occurs 40 days earlier on the eastern part of greater Phoenix. In addition, the northeast part of greater Phoenix region experiences 12 days further extreme hot days in terms of the heatwaves and 30 days longer heatwave season than other regions of the city. Similar results across study domains are presented to clarify the many differences in quantitative heatwave elements variation in a local scale. The results of this study are intended to support heatwave adaption and mitigation strategies plans for local government, such schedules for cool centers, heat emergency water distribution networks, and electrical energy delivery based on regional heatwave characteristics.