EDR/RMS-G Correlation Analysis

In the National Airspace (NAS), there are multiple in situ aircraft turbulence-related metrics in dominant use: Eddy Dissipation Rate (EDR) and Root Mean Square acceleration (RMS-g). There has been debate concerning the association between EDR and RMS-G, and while they are distinct and useful to aviation in their respective ways, they are related. EDR, by definition, is an aircraft independent measure of turbulence based on the rate at which energy dissipates in the atmosphere, whereas RMS-g derives turbulence intensity as it relates to an individual aircraft’s response. EDR is analogous to “the ambient sea state” turbulence, while RMS-g represents an aircraft response to sea state turbulence. Both metrics are calculated, rather than measured, and use aircraft sensor data as input: vertical winds, true airspeed, or aircraft vertical accelerations to derive EDR; and aircraft vertical accelerations to derive RMS-g. Furthermore, the calculation of EDR typically limits the frequency range of its input data to the inertial subrange, while RMS-g utilizes all available (i.e., sampled) frequencies, including the energy production range. However, despite their differences these two metrics are statistically correlated, as our analysis in this paper will show, leading to an improved understanding of the relationship between EDR and RMS-g.