Definition of Extreme Heat Events: Evaluation and Comparison Open Access

Han, Shengnan (2015)

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Purpose: Since there are diversity of communities engaged in heat events monitoring and research, numerous definitions are currently being used to identify extreme heat events from a variety of perspectives. However, the various definitions can also lead to some miscommunication and, from a public health perspective, differences in exposure characterization. So the difference between different definitions should be evaluated.

Methods: in order to illustrate how different the definitions can be, the geographic patterns and trends for 18 cities in the nine U.S. climate regions are studied, and three definitions are selected to be compared and evaluated: the U.S. National Weather Service Heat Index, the Australia Bureau of Meteorology Excess Heat Factor, and Spatial Synoptic Classification Weather Type. Two famous heat waves, 1995 Chicago heat wave and 2013 Phoenix heat wave, are selected as cases to compare the definitions in detail.

Results: the results show that although all the three definitions can recognize extreme heat events, there are still a lot of differences between them. In this paper, the measures' variances, spatial and temporal differences, and their ability to identify the severity of extreme heat event are discussed. Each definition is evaluated by the same metrics.

Conclusions: the differences between the three definitions are significant. Every definition has its flaws, so researcher should pay extra attention when they measure the relationship between extreme heat events and health outcomes.

Table of Contents

1. Background. 1

2. Method. 3

2.1 Data. 3

2.2 JN Definition. 3

2.3 SSC Definition. 5

2.4 NWS Definition. 6

2.5 Comparison and Evaluation. 6

3. Results. 7

3.1 July 1995 heatwave in Chicago. 7

3.2 Summer 2013 heatwave in Phoenix. 8

4. Discussion. 8

4.1 Variance. 8

4.2 Spatial Difference. 9

4.3 Temporal Difference. 9

4.4 Severity. 9

4.5 Evaluation. 10

4.6 Limitation. 11

5. Conclusion.12

References. 13

Tables & Figures. 14

Appendices. 18

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