Heat wave metrics

Metric	Description	Reference
HWN (Heat wave number)	The annual number of heat wave events	Fischer & Schär 2010
HWF (Heat wave frequency)	The sum of participating heat wave days per year	Fischer & Schär 2010
HWD (Heat wave duration)	The length (in days) of the longest yearly event	Fischer & Schär 2010
HWDM (Heat wave duration mean)	The average length (in days) of heat wave events per year	Fischer & Schär 2010
HWM (Heat wave magnitude)	The average daily magnitude across all heat wave events within a year, expressed as the anomaly against the mean Tmin or Tmax	Perkins & Alexander 2013
HWMA (Heat wave magnitude absolute)	The average daily magnitude across all heat wave events within a year
HWA (Heat wave amplitude)	The hottest day of the hottest yearly event, expressed as the anomaly against the mean Tmin or Tmax	Fischer & Schär 2010
HWAA (Heat wave amplitude absolute)	The hottest day of the hottest yearly event