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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.

The first 482 MHz Wind Profiler Radar (WPR) in Europe completed with a Radio-Acoustic Sounding System (RASS) has been operated at the Meteorological Observatory Lindenberg since July 3rd, 1996 after a comprehensive study regarding the investigation of frequency compatibility between the WPR and the television channel 22 (478-486 MHz). The WPR can operate with different height and time resolutions (e. g. 250 m in the so-called Low Mode or 500 m in the High Mode). A height range of up to approximately 16 km can be realized in the High Mode. The installed WPR/RASS combination allows also the measurement of profiles of the virtual temperature with the Low Mode resolution in the height range from 500 m up to approximately 4000 m. The main objective of this contribution is the investigation of the accuracy and the availability of this new remote sensing system. First results of the accuracy can be given on the base of about 1000 intercomparisons between WPR/RASS and Rawinsonde data. The bias of the horizontal wind velocities is less than 0.4 m/s in the Low Mode and 0.7 m/s in the High Mode (from 3 to 10 km) and therefore smaller than the average accuracy of both systems. The bias of the temperature measurements is less than 1 K and can be improved by some corrections in future. A first statistics of the data availability can be shown based on nearly 6000 profiles of wind and temperature. The 80 % availability of the WPR/RASS was determined with 12.8 km for wind and 2.3 km for temperature measurements. The new possibilities of investigating the troposphere as well as the lowest part of the stratosphere are presented by measurement examples from February and March 1997.