High-spectral-resolution lidar using an iodine absorption filter for atmospheric measurements

We develop high-spectral-resolution lidar (HSRL) using an io- dine absorption filter and a narrow-band Nd:YAG laser with high- frequency-doubled output and use it for atmospheric measurements at the National Institute for Environmental Studies (NIES). The lidar system separates Doppler-broadened molecular scattering and unbroadened aerosol scattering components of the backscattered laser light, conse- quently providing direct measurements of these two signals. Due to stable and strong absorption at room temperature, iodine absorption fil- ters are easy to use and they enable high rejection against aerosol scat- tering with a short length. The measurement principle with an error analysis and the system construction of the HSRL are described. Ex- amples of aerosol and cloud observations made by the HSRL are also presented. The experimental results indicate that the HSRL is a powerful tool for quantitatively measuring aerosol and cloud optical properties. The use of a high-output laser gives our system the ability to provide stratospheric observations. We also present the HSRL measurements of the stratospheric temperature and backscatter profiles with better reso- lutions in both range and time. An example of temperature and backscat- ter measurements is shown for the altitude range from ;10 to ;40 km with a vertical resolution of 300 m and an integrated time of ; 2h .