A method is presented to improve the concept of the equivalent displacement height (EDH). The EDH is the normalized variance of an atmospheric tracer. When the tracer's altitudinal profile exhibits a strong curvature or possesses a vanishing slope, the EDH of the earlier definitions was governed by the normalization factor, namely the slope, rather than by the tracer's variance. This may lead to misinterpretations of the EDH. The introduction of the profile's curvature into the definition of the equivalent displacement height overcomes the former difficulties and allows to derive more accurate transport parameters from the EDH.