We present the design and preliminary results of a water vapor Raman lidar, developed explicitly for meteorological applications. The lidar was designed for Meteoswiss as a fully automated, eye-safe instrument for routine water vapor measurements in the troposphere. The lidar is capable of day and nighttime vertical profiling of the tropospheric water vapor with 15 to 30 min temporal resolution. The daytime operation is achieved by decreasing the solar background employing the narrow field-of-view, narrow-band technique. The daytime vertical operational range exceeds 4 km, while the nighttime range is above 7.5 km. The lidar receiver is built on a compact multi-telescope configuration coupled with fibers to a grating polychromator used for spectral separation and partial background suppression. An additional "near range" fiber in one of the telescopes increases the signal level in the near range and allows water vapor retrieval starting from 100 m. The water vapor mixing ratio is retrieved using the ratio of the water vapor and the nitrogen Raman signals. An additional detection channel for oxygen Raman signal is used for aerosol correction.
Ozone and aerosol vertical distribution and their time evolution were measured with a combined UV DIAL / 532-nm elastic lidar during the MCMA 2003 field campaign held in April-May 2003 in Mexico City Metropolitan Area (MCMA). The DIAL transmitter is based on a N2 Raman converter, pumped by the IVth harmonic of a Nd:YAG laser. The residual second harmonic radiation from the laser is used for aerosol measurements. In the DIAL part of the receiver a dual-telescope configuration ("Long" and "Short" range) is employed to reduce the dynamic range of the signals and a single 20 cm F/4 Newtonian type telescope is used for the aerosol observations at 532 nm. The DIAL wavelengths are transmitted coaxially to the long range telescope and the 532 nm beam is transmitted coaxially to the "aerosol" telescope. The DIAL receiver is equipped with a grating polychromator for spectral separation and the 532 nm receiver uses a narrowband (0.4 nm) interference filter. "Hamamatsu" 5783-06 photosensor modules detect all signals. Ozone concentration was measured to altitudes of up to 6 km AGL and aerosol to 14 km AGL. The height of the PBL was estimated from the aerosol measurements. The diurnal evolution of the PBL and ozone were studied during the campaign. Formation of a residual layer containing elevated ozone concentrations at nighttime, as well as detachment of the PBL in the late afternoon hours were observed.
A new generation Raman LIDAR system is developed for high spatial (1.5 m) and temporal (1 s) resolution humidity and temperature measurements in the lower atmosphere. A multi-telescope array is used so that a near constant LIDAR signal is obtained from 10 m out to 500 m. The system is operated in the solar blind spectral region and corrected for ozone and aerosol influences. A prism polychromator system allows for the separation of the rotational-vibrational Raman bands of water vapor, nitrogen, and oxygen molecules with 'high spectral purity' with a throughput efficiency of greater than 90 %. This LIDAR system will ultimately be used to study the structure of the lower atmosphere over complex terrain and in particular advance our understanding of turbulent blending mechanisms in the unstable atmosphere.