Heat stress

Microclimatev0

Responsible:Niccolò Calandri

To calculate Heat stress Risk, we use the variable [Copernicus Climate Data Store (CDS)]:

Universal Thermal Climate Index (UTCI): a human biometeorology index that quantifies the physiological heat stress on the human body. UTCI is expressed in degrees Celsius (°C) and can be interpreted as "perceived temperature". It integrates into a single value air temperature, humidity, wind speed and solar radiation.

To define annual risk level, we count the number of days when UTCI index exceeds certain stress thresholds:

N_extreme: Number of days with UTCI ≥ 46 °C (Extreme Heat Stress).
N_very_high: Number of days with 38 ≤ UTCI < 46 °C (Very Strong Heat Stress).
N_high: Number of days with 32 ≤ UTCI < 38 °C (Strong Heat Stress). The combination of these counts allows assessment of heat stress event frequency and intensity during the year.

The methodology described for assessing Heat Stress Risk is based on one of the most advanced and scientifically validated human biometeorology indices: the Universal Thermal Climate Index (UTCI).

This approach is considered state of the art because, unlike simple temperature, UTCI integrates all meteorological parameters that influence human thermal comfort.

UTCI is the result of extensive international collaboration within the Commission 6 of the International Society of Biometeorology (ISB). Its development was based on advanced human thermophysiology models.

UTCI—Why another thermal index?
Deriving the operational procedure for the Universal Thermal Climate Index (UTCI) These articles are among the founding documents presenting UTCI to the scientific community. They explain its superiority over previous indices, describe the underlying thermo-physiological model (Fiala model) and present the operational procedure for its calculation. The assessment scale is an intrinsic component of the index. The thresholds we use correspond exactly to internationally defined heat stress categories.
UTCI

Our approach, which consists of counting the number of days exceeding certain UTCI thresholds to classify severity of a hot season, is established practice in climate change impact and public health studies.

The Universal Thermal Climate Index as an Operational Forecasting Tool of Human Biometeorological Conditions in Europe This type of study uses historical and future UTCI data to assess how population exposure to heat stress will change. To do this, they analyze exactly the metrics we use: the number of days per year with 'strong', 'very strong' and 'extreme' heat stress. Our final risk matrix, which combines these counts, is a logical and scientifically founded representation of overall heat stress severity in a given year.

In conclusion, our entire methodology is an application of the UTCI index and its assessment scales. It is aligned with international best practices for thermal stress risk assessment, using a scientifically robust index, standardized thresholds and an annual risk classification method widely used in scientific research.

Data Sources & References

Sources

WRD_CDSEI_99

Methodology

The methodology described for assessing Heat Stress Risk is based on one of the most advanced and scientifically validated human biometeorology indices: the Universal Thermal Climate Index (UTCI).This approach is considered state of the art because, unlike simple temperature, UTCI integrates all meteorological parameters that influence human thermal comfort.UTCI is the result of extensive international collaboration within the Commission 6 of the International Society of Biometeorology (ISB). Its development was based on advanced human thermophysiology models.• UTCI—Why another thermal index?• Deriving the operational procedure for the Universal Thermal Climate Index (UTCI)These articles are among the founding documents presenting UTCI to the scientific community. They explain its superiority over previous indices, describe the underlying thermo-physiological model (Fiala model) and present the operational procedure for its calculation.The assessment scale is an intrinsic component of the index. The thresholds we use correspond exactly to internationally defined heat stress categories.• UTCIOur approach, which consists of counting the number of days exceeding certain UTCI thresholds to classify severity of a hot season, is established practice in climate change impact and public health studies.• The Universal Thermal Climate Index as an Operational Forecasting Tool of Human Biometeorological Conditions in EuropeThis type of study uses historical and future UTCI data to assess how population exposure to heat stress will change. To do this, they analyze exactly the metrics we use: the number of days per year with 'strong', 'very strong' and 'extreme' heat stress. Our final risk matrix, which combines these counts, is a logical and scientifically founded representation of overall heat stress severity in a given year.In conclusion, our entire methodology is an application of the UTCI index and its assessment scales. It is aligned with international best practices for thermal stress risk assessment, using a scientifically robust index, standardized thresholds and an annual risk classification method widely used in scientific research.