On the Relation between the Anomalous Refraction and the Local Z Term

Abstract

The effect of the anomalous refraction due to the tilting of the air-strata of equal density in the upper atmosphere is studied by applying aerological observations with the radiosonde during the years 1950–54. The inclinations of the air-strata of equal density appear to reverse their signs at the height of about 8–9 km.

The effect of the anomalous refraction shows a distinct seasonal variation which is almost similar to that of the wind effect in the lower atmosphere. Accordingly, the wind effect has been found to be a very convenient indicator of the anomalous refraction in the upper atmosphere. In the annual component of the local Z term, the effect of the anomalous refraction seems to be combined with error of the adopted micrometer value. We tried to infer the latter from the seasonal variation of the wind effect as a first approximation.

The six-monthly and four-monthly components ef the local Z term are almost free from error of the micrometer value and are mainly caused by the room refraction. Thus, the physical explanation of the local Z term has been summarized from a viewpoint of the anomalous refraction.