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  • Author or Editor: Jens Bösenberg x
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Felix A. Theopold and Jens Bösenberg

Abstract

The method of measuring atmospheric temperature profiles with differential absorption lidar (DIAL), based on the temperature dependence of oxygen absorption lines in the near infrared, is investigated in some detail. Particularly the influence of Doppler broadening on the Rayleigh-backscattered signal is evaluated, and a correction method for this effect is presented. This correction, however, requires an accurate estimate of the molecular- and particle backscatter contributions, which is hardly achievable by usual lidar inversion techniques. Under realistic conditions, resulting errors may be as high as 10 K. First range-resolved measurements using this technique are presented, using a slightly modified DIAL system originally constructed for water vapor measurements. Temperature profiles in the planetary boundary layer are obtained with a resolution of 82 m vertical and 30 min in time, showing an absolute accuracy of 4 K and an error in the temperature gradient of 0.5 K (100 m)−1. While much better resolution can certainly be achieved by technical improvements, the errors introduced by the uncertainty of the backscatter contributions will remain and determine the accuracy that can be obtained with this method.

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Christoph Senff, Jens Bösenberg, and Gerhard Peters

Abstract

A remote-sensing method to retrieve vertical profiles of water vapor flux in the convective boundary layer by using a differential absorption lidar and a radar-radio acoustic sounding system is described. The system's height range presently extends from 400 to 700 m above the surface, and flux data can be sampled with a height resolution of 75 m and a time resolution of 60 s. The results of a first measurement in July 1991 under predominantly convective conditions are presented. The resolution of the remote-sensing system apparently is sufficient to resolve the major contributions to the flux in the convective mixed layer. In addition, the advantages and limitations of this method are discussed.

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