HR: 11:50h
AN: SA12A-07    [Abstracts]
TI: Neutral Density Holes, Patches, Fountains, and Jets in the Earth's Upper Atmosphere
AU: * Schunk, R W
EM: schunk@cc.usu.edu
AF: Utah State University, Center for Atmospheric and Space Sciences 4405 Old Main Hill, Logan, UT 84322-4405, United States
AU: Demars, H G
EM: demars@cc.usu.edu
AF: Utah State University, Center for Atmospheric and Space Sciences 4405 Old Main Hill, Logan, UT 84322-4405, United States
AB: Recent satellite measurements have indicated that the thermosphere exhibits a significant amount of spatial structure and fairly rapid temporal variations. This structure and variability can result from geomagnetic storms and sub-storms, mesoscale ionospheric structures, traveling atmospheric disturbances that propagate away from the auroral oval, upward propagating tides and gravity waves from the lower atmosphere, and both rapid time variations and spatial structure in the magnetospheric energy inputs. For example, during geomagnetic disturbances and near discrete auroral features, observations have shown the thermosphere to be highly structured, with spatial scales varying from 50 to 500 km. The thermosphere was also observed to exhibit fairly rapid temporal variations, with time scales as short as 10 minutes. In addition, during periods of enhanced plasma convection, the neutral winds can become supersonic in relatively narrow regions of the polar cap. The variability and structure of the thermosphere can be associated with mesoscale (100 - 1000 km) plasma structures, such as propagating plasma patches, auroral and boundary blobs, equatorial plasma bubbles, polar cap arcs, discrete auroral arcs, sub-auroral ion drift (SAID) events, and storm-enhanced densities (SEDs). The mesoscale ionospheric structures may not only affect the local thermosphere, but the cumulative effect of multiple plasma structures may affect the global mean thermospheric wind and temperature. The thermospheric variability and structure can appear in the form of propagating atmospheric holes, neutral gas fountains, neutral density patches, and transient neutral jets. The variability associated with these and other neutral gas disturbances have been modeled with a time-dependent, high-resolution, global model of the thermosphere- ionosphere system and the simulation results and supporting measurements will be presented.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0355 Thermosphere: composition and chemistry
DE: 2400 IONOSPHERE (6929)
SC: SPA-Aeronomy [SA]
MN: 2007 Fall Meeting