The SWIR instrument
Overview
SWIR–Balloon is a new configuration of IASI–Balloon experiment
for with the detectors and filters will be modified to cover short wave infrared
spectral regions in order to perform improved nadir soundings measurements of CO‚
CO2‚ and CH4. The IASI balloon instrument is derived itself from the
Limb Profile Monitor of the Atmosphere (LPMA) instrument‚ based on a Bomem DA2
design which has been flown many times as a solar occultation FTIR for the
determination of the vertical profiles of stratospheric species like HCl and ClONO2‚
CF2Cl2‚ NO2‚ HNO3‚ and for
radiative transfer studies of major atmospheric absorbers like CO2‚
CH4 and O2. We have been able to convert the instrument from this
solar absorption configuration into a nadir looking thermal emission configuration by
replacing the suntracker with a one rotation axis acquisition mirror and a set of warm and
cold calibration blackbodies for precise radiometric calibration. The liquid nitrogen cooled
HgCdTe and InSb detectors used at high flux level in the solar configuration have been
replaced by more sensitive detectors (1 mm x 1 mm instead of 0.25 mm x 0.25 mm, higher D*) of
the same type to cover the thermal and mid–infrared region from 600 to 3000
cm-1 (16.7 µm to 3.3 µm). The scene sampled by the instantaneous field of view
(IFOV) of the instrument is analysed with a CCD visible camera (then operating during the day
only) with provision for an infrared camera (IR CCD) in the near future for night operation.
The instrument is accommodated in a stratospheric gondola with azimuth control as
shown in the figure. This gondola is operated in the field by the "Département Nacelle"
of the balloon division (BA/NA) based at CNES in Toulouse‚ France.
Data available from Ether