Instrument response effects on the retrieval of oceanic lidar

Seawater properties can be retrieved from oceanic lidar returns. However, the actual returns include the ideal returns convolved by the instrument response, which inevitably introduces retrieval error. In this paper, instrument response effects on the retrieval of oceanic lidar are analyzed from different aspects. The results demonstrate that the retrieval of the lidar attenuation coefficient near the water surface is affected by the instrument response in homogeneous water. Considering the ratio of the signal distortion region (relative error of attenuation >10%) to the maximum detection depth (three dynamic ranges) is less than 20%, the pulse width of the instrument response should be less than 10^-0.042(ns. In addition, an average relative error of 55% will be introduced to the retrieval of phytoplankton layer thickness in the stratified water, which can be reduced to 6% after correcting for the influence of the instrument response. However, a relative error greater than 20% still exists when the instrument response length is two times larger than the layer thickness. These conclusions provide guidelines to a future design of oceanic lidar.