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VLF wave modes determined by the height gains measured during the Extended Life Balloon‐Borne Observatory test flight
Author(s) -
Barnum Benjamin H.,
Holzworth Robert H.,
Dowden Richard L.
Publication year - 1996
Publication title -
radio science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.371
H-Index - 84
eISSN - 1944-799X
pISSN - 0048-6604
DOI - 10.1029/95rs02637
Subject(s) - sunrise , sunset , altitude (triangle) , very low frequency , balloon , observatory , geodesy , physics , meteorology , amplitude , ceiling (cloud) , effects of high altitude on humans , descent (aeronautics) , remote sensing , environmental science , geology , optics , astrophysics , mathematics , astronomy , medicine , geometry , cardiology
The changes with altitude of the vertical electric field from seven VLF ground‐based transmitters were measured during the ascent of the Extended Life Balloon‐Borne Observatory (ELBBO) balloon test flight from Ft. Sumner, New Mexico. The altitude profiles of the VLF vertical electric field allowed us to determine the propagation modes based on the relative amplitude changes of the VLF signals with height. Three of the VLF transmitters had signals which crossed through the dawn terminator on their paths to the balloon's receiver. The observed height gains from these three stations show that at least two models of sunrise modal interference, those proposed by Crombie [1964] and by Kaiser [1968 ], are occurring. For these three cases a time and altitude‐varying height gain signal (the ratio E (, z )/ E (0) for altitude z above the surface z = 0 ) was measured during the balloon's 70‐min ascent to an altitude of 28.5 km. This method of balloon‐measured VLF height gains allows a high level of discrimination between modes, which is shown to be a useful method for studying the phenomena of sunrise and sunset terminator effects on VLF modal interference.