The Level 1B Transmission product contains
the SAGE III atmospheric slant path transmission
profiles at 87 spectral channels, as listed in
Appendix B. The profiles are skewed vertically
and extend from sea level to an altitude of 100 km
in 0.5 km intervals. The standard deviation of the
binned transmission data is also provided for each reported altitude and
channel. These data have been geolocated and
normalized against exoatmospheric solar
measurements to produce slant path transmission
profiles. Algorithm retrievals outlined in the
Algorithm Theoretical Basis Document (ATBD)
are used to reduce and invert these data into the
Level 2 products listed in Appendices C and D.
The Level 1B product is only available for solar
measurements.
In the construction of the transmission profiles,
atmospheric density information is used to correct
for refraction effects. This information is derived
from temperature profiles interpolated to the
location and time of each SAGE III event from
global gridded meteorological analyses provided
by the National Oceanic and Atmospheric
Administration’s (NOAA’s) National Center for
Environmental Prediction (NCEP). These data
extend from the surface to a pressure-altitude of
0.4 hPa (~55 km). Above this altitude,
climatological temperature data are used from the
Global Reference Atmospheric Model - 1995
(GRAM95, NASA Technical Memorandum
4715). The composite temperature profile
information is included in the Level 1B data
product.
Note that the NCEP temperature product is also
used to correct for molecular scattering in the
Level 2 retrieval algorithm. The retrieval of
temperature directly from the SAGE III solar
measurements occurs later, downstream in the data
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03/04
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processing flow, and is reported in the Level 2
products.