HR: 16:40h
AN: U32C-03 INVITED     [PDF]
TI: Detection of atmospheric acoustic-gravity waves through ionospheric measurements using dense GPS arrays
AU: * Calais, E
EM: ecalais@purdue.edu
AF: Purdue University Department of Atmospheric Sciences, 550 Stadium Mall Drive, West Lafayette, IN 47907-2051 United States
AU: Haase, J S
EM: jhaase@purdue.edu
AF: Purdue University Department of Atmospheric Sciences, 550 Stadium Mall Drive, West Lafayette, IN 47907-2051 United States
AU: Minster, B
EM: jbminster@ucsd.edu
AF: Institute of Geophysics and Planetary Physics Scripps Institute of Oceanography, 8765 Biological Grade EAMS Code 6317, La Jolla, CA 92093 United States
AB: The Global Positioning System (GPS) is now widely used to measure ionospheric electron content at both global and regional scales. It is also capable of detecting small-scale high-frequency ionospheric disturbances caused by atmospheric acoustic-gravity waves. We show examples of ionospheric perturbations caused by earthquakes, rocket launches, and large surface explosions. The neutral atmospheric waves triggered by these events couple with the motion of free electrons and ionized plasma at ionospheric heights and induce coherent fluctuations of electron densities and ionization layer boundaries that are detectable with GPS. In all cases, the ionospheric perturbations match fairly well observations made through other techniques as well as numerical models. The development of permanent networks of densely spaced and continuously recording GPS stations open up new opportunities for the study of infrasonic waves in the atmosphere and their coupling with small scale processes in the ionosphere. We show examples of infrasonic waves detected using the 250-station GPS network that covers the Los Angeles area (SCIGN). Although the signal-to-noise ratio of these perturbations is relatively small, we show that it can be considerably improved by multi-station array processing techniques derived from seismic array analysis. These techniques can also be used to determine the perturbation propagation azimuth and velocity and, eventually, to recover information about the sources of these perturbations.
UR: http://www.eas.purdue.edu/~calais/projects/ionosphere.html
DE: 1243 Space geodetic surveys
DE: 1294 Instruments and techniques
DE: 2427 Ionosphere/atmosphere interactions (0335)
DE: 2435 Ionospheric disturbances
DE: 2443 Midlatitude ionosphere
SC: U
MN: 2003 Fall Meeting