Selection of Minimum Day/Night Levels for Noisemap Contour Calculations.

摘要

This report discusses guidelines for the minimum Day/Night Level (DNL) values that should be used with NOISEMAP type computations to: (1) insure adequate accuracy of the lowest contour level for a given set of aircraft operations; and (2) minimize the number of machine computations and thereby reduce operating costs. An analysis is made of the errors introduced in the DNL contour values due to truncation of the partial DNL cutoff determined by the single event noise level or the number of aircraft operations for a particular flight path. For a given airbase and fixed volume of aircraft operations, the cutoff occurs at higher single event noise levels as the number of aircraft flight paths or aircraft classes are increased. Finer detail in describing the aircraft operations results in the cutoff noise levels being raised with an increased error at the edges of the DNL grid computations, but with a corresponding decrease in the machine running time. These DNL cutoff guidelines have been incorporated into version 3.4 of NOISEMAP. (Author)