JAXA Repository / AIREX 未来へ続く、宙(そら)への英知

このアイテムに関連するファイルはありません。

タイトルImprovements in the perturbation simulations of the global reference atmospheric model
本文(外部サイト)http://hdl.handle.net/2060/19870020552
著者(英)Cunnold, D. M.; Alyea, F. N.; Justus, C. G.
著者所属(英)Georgia Inst. of Tech.
発行日1987-10-01
言語eng
内容記述The Global Reference Atmospheric Model (GRAM) program includes the capability for simulating pseudo-random perturbations in density, temperature, pressure, or wind components along a simulated reentry trajectory or other path through the atmosphere. Some concerns were expressed by GRAM users, however, that the mean-square perturbation gradients may be too large for small values of the vertical separation Delta z. The present GRAM perturbation simulations, based on a one-step autoregressive model, yield a power spectrum versus wavenumber k which is proportional to k sup -2 at high wavenumbers. This feature also produces mean-square perturbation differences which are directly proportional to Delta z, and mean-square perturbation gradients which are inversely proportional to Delta z. Thus, root-mean-square gradients, (Delta f/Delta z) sub rms, increase with decreasing Delta a as Delta z sup -1/2. A simple modification to GRAM is suggested which overcomes this problem, i.e., which produce root-mean-square gradient that remain bound as Delta z approaches zero. Possible applications of more sophisticated simulation approaches, e.g., second order autoregressive models, or fractal model techniques, were also explored briefly but found to yield improvements which appear too small to justify their considerable added complexity for use in the GRAM programs.
NASA分類GEOPHYSICS
レポートNO87N29985
NASA-CR-181384
NAS 1.26:181384
権利No Copyright
URIhttps://repository.exst.jaxa.jp/dspace/handle/a-is/148743


このリポジトリに保管されているアイテムは、他に指定されている場合を除き、著作権により保護されています。