Ionosphere plasma holes - Modeling and diagnostic

The influence of ionosphere plasma holes on HF radio wave propagation in ap proximation of geometrical optics is studied. The results of HF radio wave propagation modeling on routes crossing ionosphere holes are presented. The natural and modeling ionosphere sections are used (we use experimental rad iotomography sections on routes: Moscow-Arkhangelsk, Moscow-Murmansk (Russi a) and Block Iland-Rabiwhol (USA)). It is shown that characteristics of HF radiowave trajectory (in coordinate: height-latitude) depend on geometrical sizes of hole and the direction, point, angle and frequencies of sounding. It is shown that the asymmetry of electron density distribution results in qualitative and quantitative distinctions of waves trajectories characteri stics in dependencies on direction propagation. The characteristic modes of HF radio wave propagation through hole are emphasized - one hop, captured by channel E-F, captured by hole, trapezifrom and so on. The higher interes t presents the family of trajectories captured by hole. On estimations, the longest time-delay for different conditions makes up to 23 ms (or range up to 7000 km). It is possible to say, that the hole in ionosphere can be the trap of HF radiowave. It is discussed conditions of capture and keeping of radio wave by ionospheric hole. The fact, that holes in top ionosphere are long-living and large scale formations, indicates that disregard of radiow ave propagation effects, connected with holes, will result in data distorti on or misunderstanding of ionosphere monitoring and control by radiosoundin g in HF radiowave range. (C) 1999 Published by Elsevier Science Ltd. All ri ghts reserved.