HR: 0800h
AN: SA11A-0289    [Abstracts]
TI: Thermospheric Neutral Density Cooling Determined from a 40-Year Satellite Drag Database
AU: * Marcos, F A
EM: frank.marcos@hanscom.af.mil
AF: Air Force Research Laboratory, AFRL/VSBXT 29 Randolph Road, Hanscom AFB, MA 01731-3010, United States
AU: Bowman, B R
EM: bruce.bowman@peterson.af.mil
AF: Air Force Space Command, AFSPC/A9AC Atrium II, Suite 212 1150 Academy Park Loop, Colorado Springs, CO 80910, United States
AU: Grossbard, N
EM: neil.grossbard.ctr@hanscom.af.mil
AF: Boston College, 140 Commonwealth Ave, St. Clement's Hall, 410, Chestnut Hill, MA 02467-3862, United States
AU: Delay, S H
EM: delay@bc.edu
AF: Boston College, 140 Commonwealth Ave, St. Clement's Hall, 410, Chestnut Hill, MA 02467-3862, United States
AB: Satellite drag measurements have proven a valuable tool for detecting long-term changes in thermospheric density. An extensive density database derived for the period 1970 – 2000 indicated an average decline in thermospheric density of about 1.7 percent per decade at 400 km altitude. Our database has been extended to fully cover the period 1966-2006. In addition subsets of data have been extended back to solar minimum in 1964 and ahead to the beginning of solar minimum in 2007. We therefore can examine trends for five solar minima. All data are generated from actual radar tracking observations to form precise orbit and drag/density data with improved accuracy and one-day resolution. Satellites with relatively high eccentricities were used to achieve long lifetimes and relatively localized latitude and local time resolution. Data are compared to the Jacchia 1970 and NRLMSIS empirical models. The model representations have also been enhanced by replacing their climatological average semiannual variations with realistic values derived for each satellite. By significantly reducing model errors, this procedure permits accurate representation of thermospheric cooling as a function of solar flux. Trends are also deduced for the first time in terms of thermospheric temperature changes. The derived thermospheric cooling is further analyzed as a function of altitude (250-550 km), latitude, season, local time, solar flux and geomagnetic activity.
DE: 0350 Pressure, density, and temperature
DE: 1610 Atmosphere (0315, 0325)
DE: 3309 Climatology (1616, 1620, 3305, 4215, 8408)
DE: 7924 Forecasting (2722)
DE: 7969 Satellite drag (1241)
SC: SPA-Aeronomy [SA]
MN: 2007 Fall Meeting