R' Eastes1, W' McClintock2, A' Aksnes1, D' Anderson3, L' Andersson2, A' Burns4, S' Budzien5, M' Codr

1
R. Eastes1, W. McClintock2, A. Aksnes1, D.
Anderson3, L. Andersson2, A. Burns4, S.
Budzien5, M. Codrescu3, R. Daniell6, K. Dymond5,
F. Eparvier2, J. Harvey7, T. Immel8, A.
Krywonos1, M. Lankton2, J. Lumpe9, G. Prölss10,
A. Richmond4, D. Rusch3, S. Solomon4, D.
Strickland9 and T. Woods31. Florida Space
Institute, MS-FSI, Kennedy Space Center, FL 32899
United States 3. NOAA-SEC and CIRES-Univ. of
Colorado, 325 Broadway, Boulder, CO 80303 United
States 2. Laboratory for Atmospheric and Space
Physics, University of Colorado, Boulder, CO
80309 United States 4. NCAR, PO Box 3000,
Boulder, CO 80307-3000 United States 5. Naval
Research Laboratory, Washington, DC 20375-5352
United States 6. Ionospheric Physics, Stoughton,
MA 02072-2226 United States 7.CREOL, University
of Central Florida, Orlando, FL 32816 United
States 8. Space Science Lab., Univ. of
California, Berkeley, CA 94720 United States
9.Computational Physics, Inc., 8001 Braddock Rd,
Suite 210, Springfield, VA 22151 United States
10. Institut für Astrophysik und
Extraterrestrische Forschung, Auf dem Hugel 71,
Bonn, 53121 Germany
Global-scale Observations of the Limb and Disk
(GOLD)

• ABSTRACT
• The Global-scale Observations of the Limb and
  Disk (GOLD) experiment is an ultraviolet imager
  being considered for flight on a geostationary
  (GEO) satellite as part of the upcoming Radiation
  Belt Storm Probes (RBSP) mission. On the daytime
  disk, high spectral resolution observations will
  give the first global-scale images of the neutral
  temperatures in the lower thermosphere (near 150
  km). Limb measurements of atmospheric emissions
  and stellar occultations will provide
  complementary temperature data at higher
  altitudes, as well as a direct measurement of the
  thermospheric O2 density profile. In addition,
  GOLD will perform more familiar measurements,
  such as the atomic oxygen to molecular nitrogen
  (O/N2) ratio and night-time O density. From GEO,
  GOLD will almost continuously observe the same
  hemisphere and provide daily measurements at all
  local times. The simultaneous measurements of
  (O/N2) and neutral temperature will enable
  advances in ionosphere-thermosphere modeling
  capabilities and allow us to understand (1) the
  global-scale response of the thermosphere and
  ionosphere to geomagnetic and solar forcing (2)
  the global-scale tidal amplitude and phase
  variations and (3) the causes of small-scale
  ionospheric density irregularities.
  
• I. Concept
• The Global-scale Observations of the Limb and
  Disk (GOLD) mission of opportunity will fly an
  ultraviolet (UV) imager on a geostationary
  satellite to measure densities and temperatures
  in the thermosphere and ionosphere.
• II. Mission
• Fly in geostationary orbit on commercial
  satellite (below)
• Continuous coverage over Americas
• GOLD included in request for proposals (RFP) by
  commercial company for future satellites. Launch
  in 2012 on second in series of satellites

IV. Data Flow, Models Results Shown below is
the flow of information from the observations to
the results. Measurements made by each of the two
channels is included, as is the information
derived from those measurements, some of the
models that will be used, and the results.
Observations of bubbles in the nighttime
ionosphere provide essential data for answering
the third question 3. What are the causes of
small-scale ionospheric density irregularities?
Simulated observations of nighttime bubbles
(25, 50 100 km widths)
Simulations of GOLD Low-Resolution
135.6-nm imaging at the nominal resolution (100
km x 100 km) and cadence (30 minutes to image the
entire disk) with the sub-spacecraft point (-85
degrees longitude). Equatorial ionospheric
bubbles are simulated as latitudinally extended
90 reductions in PIM densities in a volume that
rises with increasing time and shears with
altitude and latitude of the magnetic foot-point.
Sets of three bubbles with 25, 50, and 100 km
widths are simulated. Bubbles seen in the images
can be clearly identified in average counting
rates from the 12-18 magnetic latitude range,
shown below each image. At nadir, 25 km wide
bubbles are seen when observing at 100 km
resolution, while nearer the limb, bubbles with
50-km scales are seen. (For more information see
talk by T. Immel, SA42A-04)
III. Questions Answered GOLD observations will
advance understanding of global-scale changes in
the thermosphere and ionosphere. GOLD will answer
three questions 1. What is the global-scale
response of the thermosphere and ionosphere to
geomagnetic and solar forcing?
2. What are the global-scale tidal amplitude
and phase variations? Temperatures of neutrals
on the dayside provide essential information for
answering these two questions. (a) TIEGCM model
temperatures for altitudes near 180 km (quiet
time) (b) 1 sigma
uncertainties in temperatures retrieved from
simulated observations at 2 hour cadence and
solar zenith angles less than 70
degrees For information on limb
observations see poster by D. Rusch, SA33A-08.