Physics
Scientific paper
Nov 1997
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1997jastp..59.2185m&link_type=abstract
Journal of Atmospheric and Terrestrial Physics, v. 59, p. 2185-2202.
Physics
18
Scientific paper
Previous investigations of the natural resonances of the atmosphere (`normal modes') focused on oscillations whose energies are confined to tropospheric/stratospheric altitudes. Given that a broad spectrum of forcing is also present in the mesosphere and lower thermosphere (MLT) because of gravity wave dissipation, solar radiation absorption, Joule heating, etc., one might ask what type of resonance characteristics the upper atmosphere possesses. The present work seeks to identify and characterize those natural oscillations present in the ITM, and to compare with those realized in the lower atmosphere. Such information is potentially useful for interpreting observations of the ITM and first-principles model calculations. A 2D linearized perturbation model (Global Scale Wave Model-GSWM) is used here to determine the spectral response of the ITM. In a manner similar to that of Salby (1981a), the atmosphere is forced over a range of periods, and the total response (kinetic and potential) is examined. The forcing is placed at the base of the thermosphere (approx. 100-130 km) and so is representative of UV solar radiation absorption, the deposition of horizontal momentum by vertically propagating gravity waves and joule heating. It is found that the ITM region does not exhibit the same response characteristics as the lower atmosphere; the usual peaks at 2, 5, 10 and 16 days are not present. Instead the natural responses occur near periods 14, 9, and 7 h for westward symmetric waves; 11, 9 and 5 h for westward asymmetric waves; 38, 20, and 13 h for eastward symmetric waves; and 15, 12, and 9 h for eastward asymmetric waves for zonal wave numbers 1, 2 and 3 respectively. These periods and dependencies on zonal wave number are very similar to those of gravitational normal modes in an isothermal atmosphere without mean winds. Observational data which provide evidence for the realizations of these theoretical results in the atmosphere are reviewed.
Forbes Jeffrey M.
Meyer Christian Knowlton
No associations
LandOfFree
Natural oscillations of the ionosphere-thermosphere-mesosphere (ITM) system does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Natural oscillations of the ionosphere-thermosphere-mesosphere (ITM) system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Natural oscillations of the ionosphere-thermosphere-mesosphere (ITM) system will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-923865