Calibration of elastic scattering lidar at 1064-nm channel using the water-phase and cirrus clouds

Lidar calibration is important for the elastic-scattering lidar at 1064-nm to quantify the aerosol backscatter profile. Because of the weak molecular scattering at 1064-nm, the conventional calibration approach normalizing the lidar return to molecular reference value has the large uncertainty at the wavelength 1064-nm. Alternatively, as the good natural targets, water cloud and cirrus cloud have been applied for lidar calibration, but the detailed comparisons of these cloud methods have not been done. In this study, we explored the calibration methods for 1064-nm channel with the water-phase and cirrus clouds based on an elastic-Raman lidar. Good consistency was illustrated by noting that the relative differences of their daily averages were smaller than 15%. Calibration constants taken using both methods showed the compatibility as evidenced by the stability (< 7 %) over a 2-month long period. We further applied the calibration result to obtain aerosol backscatter coefficient and column lidar ratio at 1064-nm by constraining lidar-integrated backscatter profile with sunphotometer-measured aerosol optical depth and showed that under prescribed conditions, this method had less uncertainty than the result based on Fernald processing.