High-spectral-resolution lidar for ocean biological carbon pump studies
Processes and strengths of the ocean's biological carbon pump are significant to the study of ocean carbon cycle. However, the development and the utilization of the ocean's biological carbon pump are greatly limited because of human's limited knowledge of the ocean. Remote sensing methods have played important roles in understanding and exploring the ocean, and the lidar is one of the most outstanding representatives for its high spatial and temporal resolution, especially the ability of the vertical detection. High-spectral-resolution lidar (HSRL) employs an ultra-narrow spectral filter to separate scattering signals between particles and water molecules without assuming a lidar ratio, and obtains the optical properties of the ocean with a high accuracy. Nevertheless, the complexity of the seawater causes variable optical properties, which gives huge potentiality to develop the HSRL working at different wavelengths in order to promote the inversion accuracy and increase the detection depth. The field-widened Michelson interferometer (FWMI), whose central transmittance can be tuned to any wavelength, can be employed as the HSRL spectral filter and solve the problem that the operating wavelength of the iodine filter cannot change. Moreover, the FWMI has a very large field of view, which gives its superiority over Fabry-Perot interferometer that is an another popular HSRL filter. The principle of the HSRL based on the FWMI designing for the ocean remote sensing will be presented in detail. Furthermore, the availability of the application of the FWMI influenced by the disturbance of the states of Brillouin scattering is analyzed and the preliminary theory shows that the HSRL instrument basing on FWMI could be employed in the marine remote sensing with a high accuracy.