HR: 1340h
AN: SA33A-1069    [Abstracts]
TI: CHAMP Density Dependence on Geomagnetic Indices
AU: * Bruinsma, S L
EM: sean.bruinsma@cnes.fr
AF: CNES, Department of Terrestrial and Planetary Geodesy, 18, Avenue E. Belin, Toulouse, 31401, France
AU: Forbes, J M
EM: forbes@colorado.edu
AF: Department of Aerospace Engineering Sciences, University of Colorado, UCB429, Boulder, CO CO 80390, United States
AB: The STAR accelerometer on the CHAMP satellite has made it possible to accumulate near-continuous records of thermosphere density at approximately 400 km altitude since May 2001. The response of the thermosphere under extremely quiet geomagnetic conditions, as well as for virtually every significant geomagnetic storm and all levels of activity in between, has been recorded during this period. The solar activity has decreased since the beginning of the mission, when the solar cycle was at its peak, to minimum conditions or nearly so at the end of 2006. CHAMP is in a near-polar and quasi-circular orbit, and complete local time sampling is obtained about every 4 months. Therefore, this density dataset offers unique opportunities to study the variability of the thermosphere due to geomagnetic disturbances in relation to solar activity, season, solar local time, and latitude. In the present study, the complete CHAMP density database is analyzed in terms of orbit-to-orbit variability (global response of the thermosphere) as a function of geomagnetic indices, such as ap and sectorial am (index given for 9 latitude-longitude sectors). Density residuals, obtained by de-trending the data using moving averaging windows, are computed to that purpose. The variability is characterized by the large-scale (600 – 5600 km) and medium-scale (160 - 600 km) disturbances, which are isolated by forming the residuals. Secondly, latitude- dependent (i.e., local response) variability is evaluated by binning the densities in pertinent latitude bands (e.g., equatorial, sub-auroral, auroral).
DE: 2788 Magnetic storms and substorms (7954)
DE: 3369 Thermospheric dynamics (0358)
DE: 7969 Satellite drag (1241)
SC: SPA-Aeronomy [SA]
MN: 2007 Fall Meeting