DAYTIME TRAVELING IONOSPHERIC DISTURBANCES OBSERVED AT L-ALMOST-EQUAL-TO-4.5 IN WESTERN QUEBEC WITH RAPID-RUN IONOSONDES

Daytime traveling ionospheric disturbances (TIDs) are studied with a close‐spaced triangulation network of rapid‐run ionosondes. Observations in November and March (1985–1986) found disturbances traveling only southward, with a clockwise progression during the day from southeastward to southwestward. Further observations in May and August (1987) found travel in all directions with no apparent order or progression. These observations are contrary to earlier results in May (1982), using a wider‐spaced network in northern New England together with a chain of single stations extending northward, in which source locations appeared to be bracketed between the northern stations with waves traveling northward as well as southward from those sources. These results suggest possible seasonal control but, at present, still leave as a quandary the question of what and where the sources are. With new digital equipment it is planned to obtain longer time series of observations and the vertical component of the propagation vector. With the latter and the horizontal component the vertical inclination of the phase fronts can be obtained and they in turn can be tracked backward to source regions at any given height. Copyright 1990 by the American Geophysical Union.