In:
Atmospheric Measurement Techniques, Copernicus GmbH, Vol. 11, No. 7 ( 2018-07-02), p. 3861-3870
Abstract:
Abstract. A highly miniaturized limb
sounder for the observation of the O2 A-band to derive temperatures
in the mesosphere and lower thermosphere is presented. The instrument
consists of a monolithic spatial heterodyne spectrometer (SHS), which is able
to resolve the rotational structure of the R-branch of that band. The
relative intensities of the emission lines follow a Boltzmann distribution
and the ratio of the lines can be used to derive the kinetic temperature. The
SHS operates at a Littrow wavelength of 761.8 nm and heterodynes a
wavelength regime between 761.9 and 765.3 nm with a resolving power of about
8000 considering apodization effects. The size of the SHS is
38 × 38 × 27 mm3 and its acceptance angle is
±5∘. It has an etendue of 0.01 cm2 sr. Complemented by front
optics with an acceptance angle of ±0.65∘ and detector optics,
the entire optical system fits into a volume of about 1.5 L. This allows us
to fly this instrument on a 3- or 6-unit CubeSat. The vertical field of view
of the instrument is about 60 km at the Earth's limb when operated in a
typical low Earth orbit. Integration times to obtain an entire altitude
profile of nighttime temperatures are on the order of 1 min for a vertical
resolution of 1.5 km and a random noise level of about 1.5 K. Daytime
integration times are 1 order of magnitude shorter. This work presents the
design parameters of the optics and a radiometric assessment of the
instrument. Furthermore, it gives an overview of the required
characterization and calibration steps. This includes the characterization of
image distortions in the different parts of the optics, visibility, and phase
determination as well as flat fielding.
Type of Medium:
Online Resource
ISSN:
1867-8548
DOI:
10.5194/amt-11-3861-2018
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2018
detail.hit.zdb_id:
2505596-3
