The association of polar mesosphere summer echo layers with tial modes

Autor: P. J. S. Williams, G. O. L. Jones, J. R. Palmer, H. Rishbeth
Jazyk: angličtina
Rok vydání: 1995
Předmět:
Zdroj: Annales Geophysicae, Vol 13, Pp 454-457 (1995)
Druh dokumentu: article
ISSN: 0992-7689
1432-0576
DOI: 10.1007/s00585-995-0454-8
Popis: The occurrence of PMSEs with time of day shows a semi-diurnal variation with minima at 8 and 20 h LT. PMSE layers observed for more than 30 min show an average rate of descent of 2 km h–1. These characteristics suggest the influence of tidal winds. When the observed steady wind and diurnal and semi-diurnal tides at EISCAT are added, the overall magnitude shows a time-variation which matches the occurrence of PMSEs, and the observed rate of descent, approximately 2 km h–1. Atmospheric gravity waves also contribute to the velocity of the neutral wind. When the wave reinforces the background wind, the PMSEs are stronger and descend more rapidly, but when the wave-related velocity opposes the background wind the PMSE is weaker and it descends more slowly.
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