Ultraviolet high-spectral-resolution Doppler lidar for measuring wind field and aerosol optical properties

Abstract

An ultraviolet incoherent Doppler lidar that incorporates the high-spectral-resolution (HSR) technique has been developed for measuring the wind field and aerosol optical properties in the troposphere. An injection seeded and tripled Nd:YAG laser at an ultraviolet wavelength of 355 nm was used in the lidar system. The HRS technique can resolve the aerosol Mie backscatter and the molecular Rayleigh backscatter to derive the signal components. By detecting the Mie backscatter, a great increase in the Doppler filter sensitivity was realized compared to the conventional incoherent Doppler lidars that detected the Rayleigh backscatter. The wind velocity distribution in a two-dimensional cross section was measured. By using the HSR technique, multifunction and absolute value measurements were realized for aerosol extinction, and volume backscatter coefficients; the laser beam transmittance, the lidar ratio, and the backscatter ratio are derived from these measurements.

The Airborne Demonstrator for the Direct-Detection Doppler Wind Lidar ALADIN on ADM-Aeolus. Part I: Instrument Design and Comparison to Satellite Instrument

“…The double-edge technique is widely used to determine the Doppler shift from Rayleigh return in the UV at 355 nm (Flesia et al 2000;Gentry et al 2000;Imaki and Kobayashi 2005;Sun et al 2008), as implemented for ALADIN, or at visible wavelengths of 532 nm (Chanin et al 1989;Garnier and Chanin 1992;Souprayen et al 1999;Sun et al 2008). Double-edge lidar systems for observing the narrowband aerosol return using 1064 nm were applied for lower tropospheric winds (Korb et al 1997;Xia et al 2007;Shen et al 2008) and at 355 nm as a combined HSRL and DWL by Imaki and Kobayashi (2005). The fringe-imaging technique was applied by Abreu et al (1992), Fischer et al (1995), McGill et al (1997a,b), Irgang et al (2002), Dehring et al (2003), and Schmitt et al (2007).…”

“…The light is directed toward the optical receiver via a free optical path relay consisting of two mirrors and two lenses. In contrast, most other direct-detection lidar systems (e.g., Korb et al 1997;Souprayen et al 1999;Gentry et al 2000;Irgang et al 2002;Imaki and Kobayashi 2005;Xia et al 2007) use fiber coupling between telescope and spectrometers. The fiber coupling eases optomechanical integration and stability and generates uniform illumination of the spectrometers by spatial mode scrambling of the atmospheric signal (Grund and Eloranta 1991).…”

Fabry-Perot interferometer based Mie Doppler lidar for low tropospheric wind observation

“…Numerical least-squares optimization of the EPV function is achieved by the Levenberg-Marquardt method, applying the weight T Ϫ1͞2 ͑ j ͒. Then the function to be minimized is (27) All parameters, A, B, C, and width parameters, w G , w L , w I , w P and mixing parameters, L , I , P , in Eq. (27), are treated as independent variables.…”

“…Then the function to be minimized is (27) All parameters, A, B, C, and width parameters, w G , w L , w I , w P and mixing parameters, L , I , P , in Eq. (27), are treated as independent variables. It has been claimed that the maximum deviation of EPV function from the Voigt function is within 0.12%, which can be tolerated in this context [34].…”

“…The wind velocity measurement in the upper troposphere and stratosphere was realized mainly by detecting the molecular Rayleigh backscatter [19 -22]. In the low troposphere, aerosols provide a nearideal scattering source, because Mie backscattering is not significantly broadened from the original laser bandwidth [23][24][25][26][27]. Thus, the Mie Doppler lidar using the double-edge technique can achieve a higher sensitivity value of ten times the Rayleigh Doppler lidar [7,8].…”