HR: 1340h
AN: SA13A-1089 [Abstracts]
TI: Remote Sensing of the Lower Thermosphere by Solar X-ray Imaging During Occultations
AU: * Hill, S M
EM: steven.hill@noaa.gov
AF: NOAA SWPC, 325 Broadway, Boulder, CO 80305,
AU: Viereck, R
EM: rodney.viereck@noaa.gov
AF: NOAA SWPC, 325 Broadway, Boulder, CO 80305,
AU: Akmaev, R
EM: rashid.akmaev@noaa.gov
AF: NOAA SWPC, 325 Broadway, Boulder, CO 80305,
AB:
Occultations of the Sun by Earth as viewed by a soft X-ray imager offer unique insight into the structure of the
lower thermosphere (100-400 km). An initial analysis of GOES-12 Solar X-ray Imager (SXI) data demonstrated the
utility of this technique, particularly the ability to instantaneously gain spatially resolved (better than 10km
resolution) transmission measurements both in altitude and latitude. The GOES-13 SXI was launched in May
2007 and marks a significant improvement over the previous instrument in terms of spatial resolution, sensitivity,
and reduced wide-angle scattering. We analyze GOES-13 observations from September 2006 and compare them
to GOES-12 observations in terms of signal-to-noise, background levels, and apparent small-scale spatial
structure. The transmission observations are modeled using the NRLEUV solar spectral model and the MSIS
neutral atmosphere, both driven by the F10.7 solar activity proxy, and then convolved with the SXI response
function. Discrepancies between the model and observations are investigated with regard to thermospheric
cooling models and other observations of thermospheric density by independent means. The SXI thermospheric
data are highly accurate because they are "self-calibrating" relative measurements. Sustained, long-term SXI
observations are assured since the SXI program and the Solar Ultraviolet Imager (SUVI) follow-on are planned to
operate through 2030. Thus, these observations will offer a valuable measure of cyclic and secular changes in
the thermosphere over multi-year to decadal time-scales.
DE: 0355 Thermosphere: composition and chemistry
DE: 0358 Thermosphere: energy deposition (3369)
DE: 0360 Radiation: transmission and scattering
DE: 3369 Thermospheric dynamics (0358)
SC: SPA-Aeronomy [SA]
MN: 2007 Fall Meeting