Atmospheric Structure Deduced from Forward‐Scatter Wave Propagation Experiments

Abstract

This review is concerned with the relative potentials of various experimental radio techniques from the point of view of determining the atmospheric fine‐scale structure. After having derived a unified set of simple approximate expressions for the ‘measured quantity’ in terms of parameters describing the refractive‐index time‐space structure, some of the more important sources of error are discussed. Finally, on the basis of numerous experimental results, the form of the refractive‐index spectrum is deduced by using the previously derived theoretical expressions.

On the use of forward scatter techniques in the study of turbulent stratified layers in the troposhere

“…The validity of the -~ law inertial subrange cannot be determined from beamswinging experiments without knowledge about the parameter a. For details the reader is referred to Gjessing (1969). (b) We shall now address ourselves to the problem of scattering (specular reflection) from a non-turbulent atmospheric layer.…”

“…If we do, we shall essentially be measuring our own beamwidths. Referring to Gjessing (1969) for details, it can be shown that the vertical correlation distance is given by…”

“…A shear zone such as that in (b) will sharpen the boundaries of the turbulent layer, increase the variance of n within the layer and ultimately decrease the gradient of the mean refractive index within the layer. The contribution to the resultant scatter field from the (a), (b) and (c) structures are randomly phased and can thus be added on a power basis (Gjessing, 1969). It is therefore permissible to treat the structures individually and add the individual results.…”

“…The survey represents to a large extent a continuation and an extention of the review given at the preceding IUCRM Colloquium (Gjessing, 1969). In that previous review, emphasis was placed on the study of an essentially homogeneous atmospheric structure in the sense that it was assumed that the form of the refractive index spectrum remains invariant within the spatial atmospheric region under investigation.…”

“…Following the procedure adopted in the previous review (Gjessing, 1969) and to some extent basing the work on the results of this contribution, we shall study the major techniques individually with a view to establishing to what extent a stratified atmospheric structure influences the quantities measured in the individual experiments.…”