LAYER TRUNCATION AND THE EULERIAN LAGRANGIAN DUALITY IN THE THEORY OFAIRGLOW FLUCTUATIONS INDUCED BY GRAVITY-WAVES/

The theory of airglow fluctuations observed from the ground is often a dvanced by numerical integration of certain parameter combinations thr ough the depth of a model emitting layer. Practical requirements oblig e the layer to be truncated above, if not also below, the heights of g reatest emission intensity. If the analysis is of an Eulerian type, th is truncation requires that edge effects be taken into account if the results are to represent the true situation properly, but no such corr ection is normally required if the analysis is of a Lagrangian type. T he nature of the correction is discussed both for thin layers and for thick layers, and the distinction between the Eulerian and Lagrangian approaches is clarified. The theory for limb-viewing measurements made from spacecraft is somewhat different and is touched upon briefly. Co pyright (C) 1996 Elsevier Science Ltd.