Instruments:wup

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Wuppertal Spectrometer

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The Wuppertal OH Spectrometer is operated by the University of Wuppertal.

Instrument/Model Description

The Wuppertal, Germany (51.3N, 7.2E) Czerny-Turner grating spectrometer scans in the near infrared between 1.05 - 1.74 um with a spectral resolution of about 450. It has been operated by the University of Wuppertal since 1980. The instrument measures the nightglow hydroxyl [OH*]. The [OH*] emission layer is centered near 87 km (+/-2 km) with a thickness of about 9 km.

Measured parameters are the hydroxyl Meinel band rotational temperature (Code 812) in tenths of Kelvin. To reduce NLTE effects as much as possible, the (3,1) transition lines P1(2), P1(3) and P1(4) near 1.5 um are chosen for the measurements. More than 3100 average nightly mean temperatures are available continously from July 1980 until now with a gap in 1985/86. The instrument field-of-view in the zenith has a horizontal resolution of 20x20 km^2 (with respect to 86 km altitude). One spectrum is measured in 90 s.

Rotational temperatures are derived from the relative intensities of the three lines. Hence, if there should be changes of spectrometer sensitivity, atmospheric transmission, or other factors the derived temperatures would not be affected unless such changes are wavelength dependent. Even in that case, influences would be small because the three line are close together (1.524 um, 1.533 um, 1.543 um).

The relative error of nightly mean temperature values is estimated to be 1-2 K. This is derived from measurements during the whole night, and therefore, it still contains some atmospheric variability. Thus, the value must be considered as an upper limit for the relative error. The absolute temperature error is of the same magnitude. Spectral and absolute intensity calibrations are performed about once per year.

References

M. Bittner, D. Offermann, H.-H. Graef and M. Donner An 18 year time series of OH rotational temperatures and middle atmosphere decadal variations, submitted to J. A. T. P., 2000.
M. Bittner, D. Offermann, and H.-H. Graef, Mesopause temperature variability above a midlatitude station in Europe, J. Geophys. Res., 105, 2045-2058, 2000.

Summary Plots for Wuppertal Spectrometer


-Revised 10 Jan 2006 by Barbara Emery