Foil clouds as a tool for measuring wind structure and irregularities in the lower thermosphere (92–50 km)


  • H. U. Widdel


Improvements of observation techniques allow a detailed interpretation of results obtained by radar tracking of a descending foil cloud (“chaff”) target. Preposition is that the aerodynamic characteristics of the chaff is properly matched to the environment and that the size of the chaff cloud is kept small during deployment. By this, uplift motions seen at certain height levels could be identified as real motions not caused by radar tracking errors. Further, effects believed to be caused primarily by laminar separation of flow and not by turbulence were observed. This is illustrated by some results obtained during the MAP/WINE campaign winter 1983/1984 over Andenes (Northern Norway).