Definition

Eddy dissipation rate (EDR) is an objective, aircraft-independent, universal measure of turbulence based on the rate at which energy dissipates in the atmosphere. EDR is the official atmospheric turbulence intensity metric for the International Civil Aviation Organisation (ICAO) and the World Meteorological Organisation (WMO).

Description

Pilot reports (PIREPs) on turbulence are inherently subjective. What is light turbulence to a B747 might be perceived as moderate to severe for a small single-engine aircraft. EDR provides a measurement that is not based on any particular aircraft, but its values can be referenced against aircraft size.

EDR values range from 0 to 1. The effect of a particular EDR value on an aircraft will depend on the size (weight) of the aircraft. For example, an EDR of 0.24 will be moderate turbulence for an A320 but light turbulence for a B777. (Source: Improvements to the World Area Forecast System, ICAO, Nov. 2020.)