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Title: Meteorological causes of anomalous microwave propagation
Author: Jones, T.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1993
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This thesis is concerned with the influence of the weather on radio signals on surface-to-surface paths, looking particularly at the effects of fronts. The radio-meteorology of anticyclones is well understood [COST 1991], but that of fronts is less so, despite the knowledge that fronts can sometimes cause very severe radio interference through anomalous signal propagation (anaprop). A statistical analysis is made of two years signal data from seven paths in the UK and to the Netherlands. By classifying weather conditions into 24 different types, the effects of different types of weather as causes of anaprop have been determined. The results confirm the belief [Bye 1988a] that the majority of anaprop occurs under anticyclonic conditions, and that fronts are a relatively insignificant cause of anaprop. The results for the different weather and path types are presented in a set of 'interference data sheets', allowing rapid comparison of the effects of different weather conditions on signals for land and sea paths. This analysis is one of only two that examine the effects of different weather conditions on signals, and considers a far greater amount of both signal and weather data than the other study [Spillard 1991]. To examine how fronts can cause anaprop, existing meteorological conceptual models [e.g. Browning 1985] are adapted to show where super-refractive layers occur. The models examine ana- and kata-fronts (both warm and cold), as well as warm and cold occlusions. For each type of front, qualitative predictions of the likelihood of anaprop are given. The conceptual models are verified in two ways. Using dropsonde data from the FRONTS'87 project, three fronts are examined at resolutions far higher than can be obtained from routine observations. Super-refractive layers are found where the conceptual models predict them, and it is possible to make estimates of the location and strength of these layers.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available