Extreme Heat Climate Inspector

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Variable
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Changes in Extremes
Seasonal Cycle

Welcome to Extreme Heat Climate Inspector!

The Extreme Heat Climate Inspector is an interactive web application which expands GIS mapping and graphing capabilities to visualize projected heat. The data displayed in this app were produced at NCAR for the NASA-funded study, "System for Integrated Modeling of Metropolitan Extreme heat Risk" (SIMMER).

How to use this app?

  • Click on the map to explore how temperature and heat indices may change from present-day climate to mid-21st century.
  • Select a geographic location by typing its name or by clicking on the map.
  • Hover mouse over the graphs to see how heat variables may change over time.
  • Change variables to explore differences among heat indices.
  • Download images and data for your selected location.
  • Use help links for questions.

Use the search box to search for place names. A place name may be the name of a city, county, or state. Only cities with a population greater than 500 were included. Search strings should contain only plain ASCII characters and use widely accepted international or English names.

Examples:

Search for "Boulder, Colorado",         not for "80301"

Do not use zip codes or geographic coordinates. Only placenames will be matched. Search results are sorted first by the strength of string matching to the input search string, and then in descending order by population. Search results are limited to the top 20 matches. The search results dialog will give search options as well as additional information, such as the county name, province or state name, and country. Place name data is based on the Geonames geographical database (http://www.geonames.org/)

Temperature is the bulk temperature of the air, not the surface (skin) temperature.
 
Apparent Temperature is the perceived temperature derived from either a combination of temperature and wind (Wind Chill) or temperature and humidity (Heat Index) for the indicated hour. (http://www.nws.noaa.gov/ndfd/definitions.htm)

Apparent Temperature (C) = Ta + 3.30e - 0.70ws - 4.0
Where:

Ta = air temperature (°C)
e   = water vapor pressure (kPa)
ws = 10-m height wind speed (m/s)

Citation: Steadman, R.G. (1994). Norms of apparent temperature in Australia, Aust. Met. Mag., 43, 1-16

National Weather Service (NWS) Heat Index is a combination of ambient temperature and humidity that approximates the environmental aspect of the thermal regime of a human body, with the NWS thresholds representing a generalized estimate of the onset of physiological stress (http://www.srh.noaa.gov/ama/?n=heatindex)

Heat Index = -42.379 + 2.04901523T + 10.14333127R - 0.22475541TR - 6.83783 x 10-3T2 - 5.481717 x 10-2R2 + 1.22874 x 10-3T2R + 8.5282 x 10-4TR2 - 1.99 x 10-6T2R2
Where:

T - air temperature (F)
R - relative humidity (percentage)

Citation:  Robinson, P.J. (2001) On the Definition of a Heat Wave, J. Appl. Meteor., 40, 762–775. doi:http://dx.doi.org/10.1175/1520-0450(2001)040<0762:OTDOAH>2.0.CO;2
 
Humidex is used by Canadian meteorologists to describe how hot the weather feels to a person, by adding the effect of heat and humidity.

Humidex = Ta + (5/9*(e-10))
Where:

Ta = air temperature (°C)
e = water vapor pressure (hPa)

Citation: Masterson, J. and F. Richardson (1979). Humidex, a method of quantifying human discomfort due to excessive heat and humidity, CLI 1-79, Environment Canada, Atmospheric Environment Service, Downsview, Ontario.

Simplified Wet Bulb Globe Temperature (SWBGT) is a measure of the heat stress in direct sunlight, which takes into account: temperature, humidity

SWBGT = 0.567Ta+0.393e+3.94
Where:

Ta = air temperature (°C)
e = water vapour pressure (hPa)

Citation: Willett, K.M., and S. Sherwood (2010). Exceedance of heat index thresholds for 15 regions under a warming climate using the wet-bulb globe temperature, Int. J. Climatol., doi:10.1002/joc.2257.
 
Discomfort Index (DI) is a combination of temperature and humidity that is a measure of the degree of discomfort experienced by an individual in warm weather.

DI = 0.5Tw + 0.5Ta
Where:

Ta = air temperature (°C)
Tw = wet bulb temperature (°C)

Citation: Epstein, Y. and D.S. Moran (2006). Thermal comfort and the heat stress indices, Ind. Health, 44:388-398.

The buttons below allow data and map images to be downloaded for offline use. The map image are provided in PNG image format, and download instructions will vary by browser. Both the extremes data and the seasonal cycle data are provided in CSV (comma-separated value) format and can be viewed in an application such as Microsoft Excel.

High heat stress days (hot days) are defined as the number of days that the daily maximum air temperature (or a heat index) exceeds the 95th percentile of the 1986-2005 RURAL daily maximum temperature (or a heat index) . High heat stress nights (warm nights) are defined similarly using the 1986-2005 RURAL daily minimum temperature. CLMU considers both RURAL and URBAN characteristics in climate simulations to better characterize the effect of urban environment on extreme heat.

High heat stress days (hot days) are defined as the number of days that the daily maximum air temperature exceeds the 95th percentile of the 1986-2005 RURAL daily maximum temperature. High heat stress nights (warm nights) are defined similarly using the 1986-2005 RURAL daily minimum temperature.

As a result of this definition, the number of high heat stress days and nights for RURAL areas is always 4.6 days and nights on average (92 summer days/nights X 0.05 = 4.6).

As a result of this definition, the number of high heat stress days and nights for RURAL areas is always 4.6 days and nights on average (92 summer days/nights X 0.05 = 4.6).

The System for Integrated Modeling of Metropolitan Extreme heat Risk (SIMMER), a NASA-funded study conducted by NCAR scientists in 2010-2014, focused on extreme heat, human health, and urban vulnerability in present and future climates. The project quantified the importance of explicitly characterizing urban properties to improve urban meteorological simulations, and the role of climate change in the future heat stress across the United States and southern Canada. Climate model simulations from SIMMER suggest high heat stress days and nights in cities across the U.S. and in some rural areas will increase substantially by the mid-21st century.

For simulating future climate and extreme heat, we used the Community Land Model (CLM) coupled to an urban canyon model to quantify present-day (PD; 1986–2005) and a projection of one possible manifestation of mid-21st century (MC; 2046–2065) rural and urban heat stress for boreal summer over the U.S. and southern Canada at fine spatial resolution (1/8° in latitude and longitude). The Weather and Research Forecasting model (WRF) was used to downscale a Community Climate System Model (CCSM4) 20th century ensemble member for PD and a CCSM4 RCP8.5 (representative concentration pathway) ensemble member for MC to provide a consistent set of atmospheric forcing variables for CLM.

We implemented five commonly used heat stress indices directly in the model. These are the National Weather Service Heat Index, Apparent Temperature, Simplified Wet Bulb Globe Temperature, Humidex, and Discomfort Index. Heat indices are calculated for both rural (vegetation/soil) and urban areas.

High heat stress days (hot days) are defined as the number of days that the daily maximum air temperature exceeds the 95th percentile of the 1986-2005 rural daily maximum temperature.  High heat stress nights (warm nights) are defined similarly using the 1986-2005 rural daily minimum temperature.

More details can be found in:
Oleson, K.W., A. Monaghan, O. Wilhelmi, M. Barlage, N. Brunsell, J. Feddema, L. Hu, and D.F. Steinhoff, 2013: Interactions between urbanization, heat stress, and climate change, Climatic Change, DOI:10.1007/s10584-013-0936-8.

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