HR: 15:10h
AN: SA13B-07    [Abstracts]
TI: Thermospheric Response to High-Latitude Energy Sources at Quiet Times
AU: * Moe, M M
EM: kmmoe@att.net
AF: Science and Technology Corporation, 23 Purple Sage, Irvine, CA 92603 United States
AU: Moe, K
EM: kmmoe@att.net
AF: Science and Technology Corporation, 23 Purple Sage, Irvine, CA 92603 United States
AB: Recent results from the CHAMP/STAR accelerometer measurements of thermospheric neutral density have brought back to our attention the existence of important energy sources at high latitudes during geomagnetically quiet times. These energy sources produce a large dayside high-latitude density bulge which is more prominent than the sub-solar density bulge. Evidence for this persistent density enhancement during quiet times has accumulated over the past 35 years. We discuss the numerous measurements of the density bulge made by accelerometers, mass spectrometers, pressure gauges, and satellite orbital decay, as well as the correlation with airglow and ionospheric observations. The energy source for this region of increased neutral density is the solar wind, after it has passed through the Earth's bow shock and magnetosphere. The region of increased density appears on the dayside of both the northern and southern hemispheres, and has a geometrical shape similar to a lunette. The central portion of the arc of the lunette coincides with the downward projection of the magnetospheric dayside cusp. Consequently, the density bulge is best described in solar-geomagnetic coordinates. The wings of the lunette extend far beyond the footprint of the dayside cusp, and are most likely energized by particles that come from other parts of the magnetosphere. The arc of the lunette is clearly displayed by airglow observations and is matched by ionospheric measurements. The corresponding neutral density bulge is much broader in geomagnetic latitude, as one might expect from the longer time constants of neutral processes. We show a Mercator projection of the global density distribution at an altitude of 400 km at 12 hours GMT as an example of the neutral density distribution produced by both the UV and corpuscular energy sources at geomagnetically quiet times.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0350 Pressure, density, and temperature
DE: 0358 Thermosphere--energy deposition
SC: SPA-Aeronomy [SA]
MN: 2004 AGU Fall Meeting