Get access

Es structure using an HF radar

Authors

  • W. R. From,

  • J. D. Whitehead


Abstract

By using an HF radar which produces a steerable beam about 4° wide and measures angle of arrival and Doppler shift of radio echoes, the structure of various types of mid-latitude sporadic E (Es) has been determined. Totally reflecting Es is a very smooth layer, tilted less than 1° from the horizontal. Partially reflecting Es consists of clouds of ionization. These clouds vary in size from a few kilometers to 25 km in the direction of movement and larger in the transverse direction. Echoes often disappear rapidly: the clouds either disappear quickly or have sharp edges. Spread Es has a curious structure of small clouds, each of which reflects only for a few seconds, but each cloud moves with the same velocity, typically 100 m/s, even though the heights of the clouds vary up to 10 km. It is difficult to reconcile this finding with the presence of wind shears.

Get access to the full text of this article

Ancillary