Development of a Scanning Dual-wavelength High Spectral Resolution Lidar for the Department of Energy ARM program.

The University of Wisconsin (UW) lidar group has built High Spectral Resolution Lidar (HSRL) instruments to support the mission of the DOE ARM program which is to improve the understanding and representation of clouds and aerosols in climate and Earth’s system models. The UW HSRL, designed to be autonomous for long term deployments, have proven to be reliable in providing range resolved aerosols and clouds optical properties measurements for permanent DOE observation sites and various DOE, NASA, and ONR multi-year field campaigns.

The current UW HSRL design allows measurements of absolutely calibrated backscatter [m^-1 sr^-1] and extinction [m^-1] at 532 nm wavelength, attenuated backscatter [m^-1 sr^-1] at 1064 nm, and depolarization ratios at the two wavelengths. The UW HSRL instruments have a scanning telescope that allows for the detection of oriented ice crystals and high-fidelity aerosol optical properties measurement close to the Earth surface throughout the planetary boundary layer.

We report on development of the two new HSRL instruments equipped with a Field-Widened-Michelson-Interferometer at 1064 nm which will give the UW HSRL the ability to perform absolutely calibrated backscatter [m^-1 sr^-1] and extinction [m^-1] measurements with scanning capability. The dual wavelength measurements will allow to quantify the size distribution of aerosols.