HR: 0800h
AN: SA31A-1121    [Abstracts]
TI: Hydroxyl and Atomic Oxygen Airglow Response to Short-Period Gravity Waves Undergoing Vertical Reflection
AU: * Snively, J B
EM: jbs231@psu.edu
AF: The Pennsylvania State University, 204 Electrical Engr. East, University Park, PA 16802
AU: Pasko, V P
EM: vpasko@psu.edu
AF: The Pennsylvania State University, 204 Electrical Engr. East, University Park, PA 16802
AB: During the ALOHA93 campaign, a short period (4.4 minute) gravity wave was observed to perturb the hydroxyl (OH NIR) and atomic oxygen (OI 557.7 nm) airglow layers such that the intensities of the perturbed emissions were 180 degrees out of phase [Taylor et al., GRL, 22, 2849, 1995]. Explanations for this phenomena have been presented in terms of dynamic phase reversals associated with complex ducted wave structure [Munasinghe et al., JGR, 103(D6), 6467, 1998] or a mesospheric bore [Dewan and Picard, JGR, 103(D6), 6295, 1998]. We here demonstrate, in general form, that airglow chemistry alone may explain such phase variations between OH and OI emissions. The lower-thermosphere forms a stable ducting region for short-period atmospheric gravity waves. These waves may be excited by tropospheric convective sources through linear and nonlinear mechanisms [Walterscheid et al., JGR, 106, 31825, 2001; Snively and Pasko, GRL, 30(24), 2254, doi:10.1029/2003GL018436, 2003]. For waves with very short periods, near 5 minutes, the lower boundary of the lower-thermospheric duct is typically located at mesopause. This altitude also coincides with several commonly-measured airglow layers, including the OH and OI emissions. Thus, short-period ducted gravity waves propagating in the lower thermosphere may be reflected in the region of the airglow layers. Waves undergoing reflection exhibit very long vertical wavelengths; phase fronts of these waves may easily penetrate multiple airglow layers simultaneously with no significant vertical dynamic phase variations. Using a two-dimensional, fully-nonlinear model describing wave dynamics and OH and OI airglow chemistry, we examine the airglow response due to short-period gravity waves undergoing vertical reflection. Numerical model results are compared with a simplified analytical model. Due to time dependence of chemical reactions, we find that significant phase differences between the OH and OI airglow emissions may arise. This effect is discussed and compared with observations depicting anti-phase OH and OI emissions associated with short-period gravity wave motions [e.g., Taylor et al., 1995]
DE: 3332 Mesospheric dynamics
DE: 3369 Thermospheric dynamics (0358)
DE: 3384 Waves and tides
DE: 0310 Airglow and aurora
DE: 0341 Middle atmosphere--constituent transport and chemistry (3334)
SC: SPA-Aeronomy [SA]
MN: 2004 AGU Fall Meeting