The lidar of the Radio Science Center for Space and Atmosphere (RASC; Kyoto, Japan) make use of two pure rotational Raman (MR) signals for both the measurement of the atmospheric temperature profile and the derivation of a temperature-independent Raman reference signal. The latter technique is new and leads to significant smaller measurement uncertainties compared with the commonly used vibrational Raman lidar technique. For the measurement of temperature, particle extinction coefficient, particle backscatter coefficient, and humidity simultaneously, only four lidar signal are needed the elastic Cabannes backscatter signal, two RR signals, and the vibrational Raman water vapor signal. The RASC lidar provides RR signals of unprecedented intensity. Although only 25% of the RR signal intensities can be used with the present data-acquisition electronics, the 1-s -statistical uncertainty of nighttime temperature measurements is lower than for previous systems and is < 1K up to 11-km height for, e.g., a resolution of 500 m and 9 min. In addition, RR measurements in daytime also have become feasible.

The design and the performance of the new Raman lidar of the Radio Science Center for Space and Atmosphere (RASC) at Kyoto University are presented. The system is located at (34.8º N, 136.1º E) near Shigaraki, Japan, where also one of the world largest atmospheric radars, the MU (middle and upper atmosphere) radar, is operated. Measurement parameters of the lidar are atmospheric temperature (with rotational Raman and with Rayleigh integration technique), water vapor mixing ratio (H 2 O Raman lidar technique), and optical particle properties. Common Raman lidar takes vibrational-rotational Raman backscatter of nitrogen as a reference signal. In contrast to this, our system makes use of the approximately 10-times stronger pure-rotational Raman signals for deriving both atmospheric temperature and a temperature independent Raman reference signal. This modification leads to a significant reduction of measurement uncertainties. With the RASC lidar, rotational Raman signals with, to our best knowledge, unprecedented intensity can be taken by means of a high-throughput receiver. This allows not only nighttime temperature measurements with a resolution of, e.g., a few minutes near the tropopause, but made also, to our knowledge, the first daytime measurements possible.

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