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The Airborne Submillimeter Radiometer (ASUR) radiometer is an
airborne radiometer measuring the thermal emission of trace
gases in the stratosphere (in an altitude range between 15 and
50 km). The instrument detects the radiation in a frequency
range between 604.3 and 662.3 GHz. This corresponds to
wavelengths of about 0.45-0.5 mm. In this frequency range a
major part of the radiation is absorbed by atmospheric water
vapor. As most of the water vapor is found in the troposphere
(in the Arctic up to 8 km, in the tropics up to 16 km altitude)
the instrument is operated on board of an aircraft flying at an
altitude of 10-12 km, such that a major part of the water vapor
absorption is avoided.
The ASUR instrument in its current configuration can measure
emission lines of the trace gases HCl, ozone, ClO, N2O, HNO3,
CH3Cl, H2O, BrO, HO2, HCN, and NO. The horizontal resolution of
the measurements ranges between 12 and 50 km and depends on
signal intensity and aircraft speed. The maximum time of
continuous operation is 10-11 hours and is determined by the
storage volume of liquid cryogen (see section Setup).
The hardware of the ASUR instrument [Whyborn et al., 1996, Mees
et al., 1995] has been developed and built in a collaboration
between SRON (Space Research Organisation of the Netherlands),
Groningen and the Institute of Environmental Physics of the
University of Bremen. The spectrometers AOS (Acousto-Optical
Spectrometer) and CTS (Chirp-Transform Spectrometer) were
developed , in the framework of an ESA/ESTEC project by the
Observatoire de Meudon, Paris, and the Deutsche Aerospace (now:
ASTRIUM), respectively.
Additional information available at
"http://www.iup.physik.uni-bremen.de/asur/general/instrument_e.html"
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