Please use this identifier to cite or link to this item:
https://hdl.handle.net/2440/12374
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Type: | Journal article |
Title: | Zonal mean and tidal dynamics from space: An empirical examination of aliasing and sampling issues |
Author: | Forbes, J. Kilpatrick, M. Fritts, D. Manson, A. Vincent, R. |
Citation: | Annales Geophysicae: atmospheres, hydrospheres and space sciences, 1997; 15(9):1158-1164 |
Publisher: | European Geosciences Union |
Issue Date: | 1997 |
ISSN: | 0992-7689 1432-0576 |
Abstract: | Interpretations of space-based measurements of atmospheric parameters in the mesosphere and thermosphere are complicated by large local-time variations at these altitudes. For this reason, satellite orbits are often preferred which precess through all local times one or more times per season. However, the local-time structure of the atmosphere is inherently non-stationary, which can lead to sampling and aliasing difficulties when attempting to deconvolve the measurements into zonal mean and tidal components. In the present study, hourly radar measurements of mesopause-region winds are used to form a mock data base which can be used to gain insight into implications of the aforementioned problems; the use of actual measurements introduces a realistic element of geophysical temporal variability. Assuming zonal symmetry (i.e., migrating tides superimposed on a zonal mean circulation), the radar measurements are sampled from the satellite perspective for orbital inclinations of 57° and 70°, and compared to the ground or true perspective. These comparisons provide realistic estimates of the errors to be expected when attempting to derive mean and tidal components from space-based measurements. For both diurnal and semidiurnal components, and the quoted satellite inclinations, acceptable errors (3–4m/srms) are obtained for data covering 24h local time (i.e., ascending plus descending nodes); the corresponding errors for single-node data (12h local-time coverage) are of order 8–11m/s, and therefore may not represent reliable estimates of the actual tidal components. There exist certain caveats in connection with the latter conclusion which are discussed. |
DOI: | 10.1007/s005850050533 |
Published version: | http://www.ann-geophys.net/15/1158/1997/ |
Appears in Collections: | Aurora harvest 7 Physics publications |
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