Using the normal-mode method of probing the infrasonic propagation for purposes of the comprehensive nuclear-test-ban treaty

摘要

We examine the problem of assessing the state of Atmospheric Acoustic Channels, that is, of the possible propagation paths of acoustic signals, based on using a priori information about atmospheric conditions. It is concluded that this can only be best accomplished through the use of global atmospheric models. Based on the normal-mode method, an analysis is made of the generalized characteristics of atmospheric waveguide such as the location of the waveguide boundaries, the mode composition, and the transmissivity of the waveguide upper and lower boundaries. The method can be used to analyze the particular paths as well as the overall situation around a given point. Furthermore, all the surrounding space (extending as far as the whole of the geosphere) is divided into regions that are accessible and inaccessible for a given mode. To determine the particular height distributions of physical characteristics over the entire path, the NRLMSISE-2000 atmosphere model and the HWM-93 wind model are used. Some of the calculated paths are compared with the known source and receiver positions and with observational results. It is concluded that the method can be used in a general assessment of the accessibility of a given region for acoustic monitoring; however, it is not sufficiently reliable to permit real-time predictions. (c) 2005 Elsevier Ltd. All rights reserved.