| Data Set Abstract |
This data set consists of the raster-averaged radiant intensities
and associated data parameters produced from data acquired by the
Mars Atmospheric Water Detectors (MAWD) onboard the Viking
Orbiters. The basic observations give temporal coverage spanning
just over two martian years and variable, but extensive, spatial
coverage of the planet. MAWD was a five-channel grating
spectrometer measuring solar radiation reflected from the surface
and atmosphere of Mars in and out of water vapor bands in the 1.4
micrometer spectral interval. The data set described here
contains the solar reflected radiant intensities (i.e.,
radiances) measured by MAWD, derived water vapor column
abundances, a derived '1.4-micrometer brightness', and
ancillary data (e.g., viewing geometry, surface elevation and air
mass). Column water vapor abundances were derived by comparing
the reflected radiant intensities in three water vapor absorption
bands to radiant intensities in the two interspersed continua
observed air mass and then normalized by the air mass to obtain a
vertical column abundance. A basic description of the instrument,
its observational modes and its derived data products is given in
[FARMER_ETAL_1977]. A description of the global and seasonal
variation of water vapor on Mars, based on the complete MAWD
observational record, is given in [JAKOSKY_FARMER_1982]. This
data set was generated from the raster-level data base
constructed during the Viking Mission on the original data
processing system (IRPS: Infrared Processing System) by the MAWD
Science Team, led by C. B. Farmer, JPL. Together with the
instantaneous field of view (IFOV) radiances and geometry, the
raster-level radiances, associated water column abundances and
ancillary data have been archived at the NSSDC (NSSDC id
75-075A-03A, 75-083A-03A). Data from the final phase of the VO-1
mission were added, supervised by R. Zurek, JPL. Eventually, the
data set was restructured, additional quality flags were
introduced, and a second estimate of the water vapor column
abundance (WFAPT, termed COLUMN_H2O_A in the data set) was added
[by R. Zurek, JPL [JAKOSKY_ETAL_1988].]. The data base was
restructured, while preserving key unique parameters, into a
consistent format with the Viking Orbiter Infrared Thermal Mapper
(IRTM) data [R. Mehlman, R. Zurek]. Both the MAWD and IRTM data
sets were then accessible with the XXFUNC package. Further
quality checking of the MAWD data was carried out by B. Jakosky,
U. Colorado. |
.png)
.png)
