Developing and Validating Heat Exposure Products Using the US Climate Reference Network

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  • 1 NCSU, North Carolina Institute for Climate Studies, Asheville, NC.
  • 2 NOAA National Centers for Environmental Information, Asheville, NC.
  • 3 North Carolina State Climate Office, Raleigh, NC
  • 4 NOAA Air Resources Laboratory, College Park, MD
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Abstract

Extreme heat is one of the most pressing climate risks in the United States, and is exacerbated by a warming climate and aging population. Much work in heat-health has focused only on temperature-based metrics, which do not fully measure the physiological impact of heat stress on the human body. The United States Climate Reference Network (USCRN) consists of 139 sites across the US, and includes meteorological parameters fully encompassing human tolerance to heat, including relative humidity, wind, and solar radiation. Hourly and 5-minute observations from USCRN are used to develop heat exposure products, including heat index (HI), apparent temperature (AT), and wet bulb globe temperature (WBGT). Validation of this product is conducted with nearby airport and mesonet stations, with reanalysis data used to fill in data gaps.

Using these derived heat products, two separate analyses are conducted. The first is based on standardized anomalies, which place current heat state in the context of a long-term climate record. In the second study, heat events are classified by time spent at various levels of severity of conditions. There is no consensus as to what defines a heat event, so a comparison of absolute thresholds (i.e., ≥ 30.0°C, 35.0°C, 40.0°C) and relative thresholds (≥ 90th, 95th, 98th percentile) will be examined. The efficacy of the product set will be studied using an extreme heat case study in the southeast US. While no heat exposure metric is deemed superior, each has their own advantages and caveats, especially in the context of public communication.

CORRESPONDING AUTHOR: jared@ncics.org

Abstract

Extreme heat is one of the most pressing climate risks in the United States, and is exacerbated by a warming climate and aging population. Much work in heat-health has focused only on temperature-based metrics, which do not fully measure the physiological impact of heat stress on the human body. The United States Climate Reference Network (USCRN) consists of 139 sites across the US, and includes meteorological parameters fully encompassing human tolerance to heat, including relative humidity, wind, and solar radiation. Hourly and 5-minute observations from USCRN are used to develop heat exposure products, including heat index (HI), apparent temperature (AT), and wet bulb globe temperature (WBGT). Validation of this product is conducted with nearby airport and mesonet stations, with reanalysis data used to fill in data gaps.

Using these derived heat products, two separate analyses are conducted. The first is based on standardized anomalies, which place current heat state in the context of a long-term climate record. In the second study, heat events are classified by time spent at various levels of severity of conditions. There is no consensus as to what defines a heat event, so a comparison of absolute thresholds (i.e., ≥ 30.0°C, 35.0°C, 40.0°C) and relative thresholds (≥ 90th, 95th, 98th percentile) will be examined. The efficacy of the product set will be studied using an extreme heat case study in the southeast US. While no heat exposure metric is deemed superior, each has their own advantages and caveats, especially in the context of public communication.

CORRESPONDING AUTHOR: jared@ncics.org
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