A High Spectral Resolution Lidar Designed for Unattended Operation in the Arctic.

files of optical depth, backscatter cross section, depolarization and backscatter phase function. All HSRL measurements are absolutely calibrated by reference to molecular scattering which is mea-sured at each point in the lidar profile (Grund and Eloranta 1991, Pirronen and Eloranta 1994). This enables the HSRL to measure backscatter cross section and optical depth without a prior assumptions about the scattering properties of the atmosphere. Rigorous error estimates can be computed for all measurements. This paper describes the design and initial testing of a new HSRL for long term unattended observations of arctic clouds and hazes. These observations are needed to improve the parameter-izations of radiative transfer in global climate models. The current HSRL requires attention by a highly trained operator and is not suited for long term measurement campaigns. Extensive modifications are required to fit this semi-trailer sized system into a package about the size of a phone booth and to allow operation and data transfer to be controlled remotely over the Internet. One of the most troublesome features of the current HSRL involves maintaining alignment of the laser beam with the receiver field of view. Alignment is sensitive to perturbations at th