On September, 7th, 15:00 local time a 400.000 m3 helium balloon was launched in Timmins/Canada. On board: The instrument TELIS of the Remote Sensing Institute. The balloon reached an altitude of 36 km during its 19 hour flight. Goal of the flight was the determination of the bromine budget in the stratosphere. Bromine has a 100fold larger ozone depletion potential compared to chlorine. About half of the bromine in the atmosphere has anthropogenic origin. Beside the bromine content the scientists are interested in the partitioning into different bromine compounds and their diurnal variation.
September 23, 2014
Measurements at 36.000 m Altitude
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Beside TELIS MIPAS-B2 (Michelson Interferometer for Passive Atmospheric Sounding, KIT, Karlsruhe), and mini-DOAS (Differential Optical Absorption Spectroscopy, University Heidelberg) were onboard. Together, these instruments form a worldwide unique chemistry mission for the tropopause and stratosphere.
TELIS (Terahertz and submillimeter LImbSounder) is a helium-cooled two-channel heterodyne spectrometer financed by DLR, developed at the DLR Remote Sensing Technology Institute, department “experimental methods”. The submillimeter wave channel (500-650 GHz) has been built by SRON (Netherlands Institute for Space Research), NL. The Terahertz channel (1800-1900 GHz) has been built at DLR, together with optics, mechanics, and instrument control. The development of TELIS benefited from the international cooperation, utilising the combined knowledge. Apart from the already mentioned organisations the University of Bern, Switzerland, the Chalmers University, Sweden, the Rutherford Appleton Laboratory, GB, and the Jet Propulsion Laboratory (USA) were involved. TELIS is a limb sounder where the observer is above the atmospheric layers to be measured. In limb sounding spectra are measured at different tangent heights with the viewing direction being slightly below horizontal. The vertical resolution is about 2 km. The instrument is operating on a stratospheric balloon. TELIS was integrated into the gondola of the MIPAS-B Fourier-transform spectrometer, which has been successfully operated for 20 years by the Institute of Meteorology and Climate Research of the Forschungszentrum Karlsruhe. Additionally, a mini-DOAS from the University of Heidelberg was part of the payload. TELIS measures the thermal emission of molecular lines against the cold cosmic background yielding concentration profiles of OH, HO2, ClO, BrO, HCl, CO, O3, H216O, HDO, H218O, H217O und HOCl.
Ballon und Gondel kurz nach dem Start
Unterhalb der Gondel die gerade abgesprengten Hilfsballons. Ballon und „flight-train“ haben zusammen eine Länge von ca. 200 m. Erst auf Flughöhe (35-40 km) bläht sich der Ballon bei einem Außendruck von ca. 5 mbar zu seiner vollen Größe (ca. 90 m Durchmesser) auf.
The combination of instruments covers all relevant bromine species. While mini-DOAS is measuring bromine oxide, BrO, in the UV (at ca. 330 nm) TELIS records rotational transitions of BrO in the subMMW range (at 480 µm). MIPAS-B2 measures bromine nitrate, BrONO2, spectra in the mid infrared spectral region (at 12.5 µm). Due to the low abundance of BrO the observation is difficult and cross-validation essential.
Bromine-containing compounds can cause ozone depletion. The emission of bromine compounds into the atmosphere is half of natural origin and half anthropogenic, e.g. from fire prevention materials, fire extinguishers, pesticides, and fungicides. Although the bromine concentration in the stratosphere – the second layer of the atmosphere – is more than 100 time lower than the concentration of also ozone-depleting chlorine the effect on the ozone layer is similar. The reason is the smaller photochemical stability of the reservoir species BrONO2, when compared to chlorine nitrate, ClONO2 . The photolysis of the reservoir species yields active species which are capable of catalytical ozone destruction.
As benefit of the Montreal protocol dedicated to the reduction of the production of ozone-depleting compounds, effective since 1989, the total chlorine amount in the stratosphere has decreased since the 1990s. The total bromine amount together with important details of its photochemistry are not as well investigated as those of chlorine. Up to now there has been no simultaneous measurement of the most important bromine-containing species BrO and BrONO2,. Thus, the determination of the total bromine amount in the stratosphere is more difficult. This is also true for the estimation of the impact of the ozone layer.
The flight yields important data towards a better understanding of the bromine budget of the atmosphere and the associated ozone destruction.
Mit an Bord war eine Kamera die alle 10 Sekunden eine Aufnahme in Blickrichtung der Instrumente lieferte.
Die gezeigte Aufnahme entstand bei einer Flughöhe von 36 km. Mangels streuender Atmosphäre ist der Himmel tiefschwarz. Die Aufnahme erinnert daher an Bilder aus dem All
