HR: 1340h
AN: SA53A-1148    [Abstracts]
TI: Forecasting of Convectively Generated Gravity Waves in the Middle and Upper Atmosphere
AU: * Hassiotis, A
EM: adh180@psu.edu
AF: The Pennsylvania State University, Department of Electrical Engineering, University Park, 16802 United States
AU: Kane, T
EM: tjk7@psu.edu
AF: The Pennsylvania State University, Department of Electrical Engineering, University Park, 16802 United States
AU: Gerrard, A
EM: agerrard@twcny.rr.com
AF: Clemson University, Department of Physics and Astronomy, Clemson, 29634 United States
AB: Model studies have shown that gravity waves excited by the thermal forcing mechanism in convection excite high-frequency waves (10-100 min) with long vertical wavelengths (greater than 20 km). Source spectra for various spatial and temporal scales of thermal forcing are now available above convective sources. When these energetic source spectra are propagated through synoptic background fields via ray-tracing methods they are able to reach middle and upper atmospheric altitudes before dissipating, and subsequently influencing the momentum budget of the region. Waves that manage to propagate deeper into the thermosphere can potentially seed instabilities such as equatorial spread-F (ESF). ESF causes scintillation in radio communications and GPS signals. The current realism of the convective source parameterizations has motivated the use of ray-tracing methods to predict some of the already observed effects of convectively-generated gravity waves in the middle and upper atmosphere. For this reason, a unique global gravity wave forecasting model called FOREGRATS (FOREcasting of Gravity waves via Ray-tracing algorithms with prescribed Tropospheric Sources) is being developed. The model will identify convective gravity wave sources in the troposphere, prescribe a realistic source spectrum, and then propagate the spectrum of waves up into the middle and upper atmosphere. In conjunction with observations at the Arecibo Observatory, which is located in a tropical convection zone, the predictability of these high-frequency/long vertical wavelength waves in the middle and upper atmosphere will be explored with FOREGRATS.
DE: 3362 Stratosphere/troposphere interactions
DE: 3369 Thermospheric dynamics (0358)
DE: 3384 Acoustic-gravity waves
SC: SPA-Aeronomy [SA]
MN: Fall Meeting 2005