Ioan Balin

Development of a multiwavelength aerosol and water-vapor lidar at the Jungfraujoch Alpine Station (3580 m above sea level) in Switzerland

The Jungfraujoch Research Station (46.55 degrees N, 7.98 degrees E, 3580 m above sea level) for decades has contributed in a significant manner to the systematic observation of the Earths atmosphere both with in situ measurements and with trace gas column detection. We report on the development of a lidar system that improves the measurement potential of highly resolved atmospheric parameters in both time and space, with the goal of achieving long-term monitoring of atmospheric aerosol optical properties and water-vapor content. From the simultaneously detected elastic-backscatter signals at 355, 532, and 1064 nm, Raman signals from nitrogen at 387 and 607 nm, and water vapor at 408 nm, the aerosol extinction and backscatter coefficients at three wavelengths and a water-vapor mixing ratio are derived. Additional information about particle shape is obtained by depolarization measurements at 532 nm. Water-vapor measurements by use of both nitrogen and water-vapor Raman returns from the 355-nm laser beam are demonstrated with a vertical range resolution of 75 m and an integration time of 2 h. The comparison to the water-vapor profile derived from balloon measurements (Snow White technique) showed excellent agreement. The system design and the results obtained by its operation are reported.

Water vapor vertical profile by Raman lidar in the free troposphere from the Jungfraujoch Alpine Station

The water vapor content in the atmosphere is an important criteria for the validation of predictive results obtained from global scale atmospheric models. Due to its non-homogeneous distribution in the troposphere, both in space and time, the water vapor content in the atmosphere may still be considered today as the largest uncertainty in our understanding of the earth radiation budget. This paper presents new results obtained by Raman lidar measurements as one of the attractive method for long-term continuous observation of the water vapor content in the atmosphere. A powerful pulsed laser beam at 355 nm is emitted and the inelastic back-scatter signals (Raman shift) from nitrogen and water vapor are recorded respectively. The ratio between the water vapor Raman shifted wavelength at 408nm and the nitrogen at 387nm gives a first estimate of the relative water vapor mixing ratio with good vertical resolution. The absolute water vapor vertical profiles are retrieved using an additional in situexternal reference value directly obtained from a local meteorological station. The Raman lidar system, operated at an altitude of 3′580 m above see level in the Swiss Alpine region at the Jungfraujoch research station, is presented, and two typical water vapor vertical profiles obtained in clear sky and in cloudy conditions are discussed and directly compared with radio sounding measurements performed by the Swiss Meteorological Station from Payerne (80 km West). A first estimate of the statistical (signal to noise) and systematic error sources is presented.