Meteorologische Zeitschrift (Dec 1998)

Field campaign LINEX 96/1 — Possibilities of water vapor observation in the free atmosphere

  • H. Steinhagen,
  • S. Bakan,
  • J. Bösenberg,
  • H. Dier,
  • D. Engelbart,
  • J. Fischer,
  • G. Gendt,
  • U Görsdorf,
  • J. Güldner,
  • F. Jansen,
  • V. Lehmann,
  • U. Leiterer,
  • J. Neisser,
  • Volker Wulfmeyer

DOI
https://doi.org/10.1127/metz/7/1998/377
Journal volume & issue
Vol. 7, no. 6
pp. 377 – 391

Abstract

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LINEX 96/1 was a field experiment to assess information content, accuracy, and availability for different remote sensing techniques measuring water vapor. An important goal of LINEX 96/1 was the test of a new Differential Absorption Lidar (DIAL) developed by the MPI für Meteorologie Hamburg. Comparisons of DIAL with rawinsonde and tethersonde measurements showed an excellent accuracy of the DIAL method in the determination of water vapor with high vertical and temporal resolution. The operation of the microwave radiometer WVR-1100 showed a high availability of water vapor and liquid water column content measurements except during rain. Microwave radiometers are reliable systems to measure the precipitable water vapor and liquid water content under unattended operational conditions with high accuracy and temporal resolution. Measurements of the water vapor column content by groundbased GPS receivers proved highly reliable. Comparisons with corresponding values of the microwave radiometer showed a bias less than 0.6 mm and a standard deviation less than 0.9 mm. The main problem of an operational use of this new information is that the evaluated data are not available in real-time because, at present, the data have to be postprocessed in a ground control center. During LINEX 96/1, possibilities for estimation of water vapor column content from sun and star photometer measurements were also demonstrated. The comparison of the precipitable water vapor content measurements of sun and star photometers, microwave radiometer, and rawinsondes RS 80 showed a good agreement. Unfortunately, the use of optical methods like sun and star photometers is restricted by cloudy conditions. The field campaign LINEX 96/1 was an important contribution to the COST Action 76 by investigation of the new possibilities measuring water vapor in the free atmosphere with the objective of improvements of our knowledge about the 4-dimensional water vapor field.

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