HR: 1340h
AN: SA23A-0379    [Abstracts]
TI: Accelerometer and Orbital Drag Thermospheric Density Inter-comparisons
AU: * Marcos, F A
EM: frank.marcos@hanscom.af.mil
AF: Air Force Research Laboratory, Space Vehicles Directorate, AFRL/VSBXT, 29 Randolph Road, Hanscom AFB, MA 01731-3010 United States
AU: Tapley, B
EM: tapley@csr.utexas.edu
AF: Center for Space Research, The University of Texas at Austin, 3925 West Braker Lane, Austin, TX 78759-5321 United States
AU: Bettadpur, S
EM: srinivas@csr.utexas.edu
AF: Center for Space Research, The University of Texas at Austin, 3925 West Braker Lane, Austin, TX 78759-5321 United States
AU: Abusali, P
AF: Center for Space Research, The University of Texas at Austin, 3925 West Braker Lane, Austin, TX 78759-5321 United States
AU: Bruinsma, S
EM: sean.bruinsma@cnes.fr
AF: CNES-Dept. of Terrestrial and Planetary Geodesy, 18, Avenue E. Belin, Toulouse Cedex 9, 3140 France
AU: Wise, J O
EM: john.wise@hanscom.af.mil
AF: Air Force Research Laboratory, Space Vehicles Directorate, AFRL/VSBXT, 29 Randolph Road, Hanscom AFB, MA 01731-3010 United States
AU: Sullivan, B
EM: sullivab@bc.edu
AF: Institute for Scientific Research, Boston College, 140 Commonwealth Ave., Chestnut Hill, MA 02467 United States
AU: Bowman, B R
EM: bruce.bowman@peterson.af.mil
AF: Hq. Air Force Space Command, 150 Vandenberg St., Suite 1105, Peterson AFB, CO 80914 United States
AB: Accelerometers on the CHAMP and GRACE satellites provide high-resolution (seconds) thermospheric neutral densities. CHAMP carries the STAR accelerometer and GRACE carries an upgraded SuperSTAR accelerometer. Both instruments are on high-inclination satellites. These data are compared to two types of orbital drag data. One set is from HASDM (High Accuracy Satellite Drag Model). This approach provides spatially and temporally varying density corrections involving tracking of some 100 satellites. A weighted least squares fit to all of the tracking data produces a global density solution with a time resolution of several hours. The second set consists of individual measurements from each of twenty radar-tracked satellites. Densities were derived using newly developed techniques to provide one-day resolution. These data are relatively localized in latitude since all satellites were in highly elliptical orbits. HASDM data are available only during two periods; the first half of 2001 and August-September 2002. Data from each accelerometer is compared to orbital drag results at different periods. CHAMP data are compared to HASDM and individual orbital drag measurements during May-June 2001. Ratios of CHAMP to HASDM, analyzed in latitude-time coordinates show that significant high latitude structures are not observed by HASDM. The ratio of CHAMP absolute density to that from HASDM also increases with latitude. GRACE data are compared to the second set of HASDM data in August 2002. Similar analyses of GRACE data trends vs latitude and of absolute densities are presented. Data sets are analyzed during quiet and disturbed conditions to compare the thermospheric density response to solar and geomagnetic inputs as observed by in situ and orbital drag measurements.
DE: 0350 Pressure, density, and temperature
DE: 0358 Thermosphere--energy deposition
DE: 0394 Instruments and techniques
SC: SPA-Aeronomy [SA]
MN: 2004 AGU Fall Meeting