Statistics – Computation
Scientific paper
Jun 1986
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1986thdy.work..221m&link_type=abstract
In its Thermosphere Dynamics Workshop, Volume 2 p 221-231 (SEE N86-29301 20-42)
Statistics
Computation
Auroral Zones, Perturbation Theory, Spherical Harmonics, Thermosphere, Transfer Functions, Turbulent Diffusion, Atmospheric Circulation, Atmospheric Composition, Atmospheric Temperature, Gravity Waves, Legendre Functions, Wave Propagation, Wave Reflection, Wind Direction
Scientific paper
Applying perturbation theory, a spectral model in terms of vectors spherical harmonics (Legendre polynomials) is used to describe the short term thermospheric perturbations originating in the auroral regions. The source may be Joule heating, particle precipitation or ExB ion drift-momentum coupling. A multiconstituent atmosphere is considered, allowing for the collisional momentum exchange between species including Ar, O2, N2, O, He and H. The coupled equations of energy, mass and momentum conservation are solved simultaneously for the major species N2 and O. Applying homogeneous boundary conditions, the integration is carred out from the Earth's surface up to 700 km. In the analysis, the spherical harmonics are treated as eigenfunctions, assuming that the Earth's rotation (and prevailing circulation) do not significantly affect perturbations with periods which are typically much less than one day. Under these simplifying assumptions, and given a particular source distribution in the vertical, a two dimensional transfer function is constructed to describe the three dimensional response of the atmosphere. In the order of increasing horizontal wave numbers (order of polynomials), this transfer function reveals five components. To compile the transfer function, the numerical computations are very time consuming (about 100 hours on a VAX for one particular vertical source distribution). However, given the transfer function, the atmospheric response in space and time (using Fourier integral representation) can be constructed with a few seconds of a central processing unit. This model is applied in a case study of wind and temperature measurements on the Dynamics Explorer B, which show features characteristic of a ringlike excitation source in the auroral oval. The data can be interpreted as gravity waves which are focused (and amplified) in the polar region and then are reflected to propagate toward lower latitudes.
Harris Isadore
Herrero Federico A.
Mayr Hans G.
Spencer Nelson W.
Varosi Frank
No associations
LandOfFree
Transfer function analysis of thermospheric perturbations 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 Transfer function analysis of thermospheric perturbations, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Transfer function analysis of thermospheric perturbations will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1834466