Estimation of Particulate Organic Carbon in the ocean from space-based polarization lidar measurements

摘要

A relationship between depolarization ratio and surface concentration of particulate organic carbon (POC) is developed from the NASA SeaWiFS Bio-optical Archive and Storage System (SeaBASS) in situ measurements and the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) active lidar measurements. This relationship provides an algorithm for estimating global POC from satellite or airborne polarization lidar measurements. Application of this relationship to CALIOP data indicates that the estimates of POC ranges from about 3.3 mg/m~3 within the South Pacific Subtropical Gyre to 1.2×10~3 mg/m~3 in the area near land are in good agreement with Moderate Resolution Imaging spectroradiometer (MODIS) POC products. Our results present depolarization ratio as a valuable tool for evaluating global POC predictions in ocean ecosystem. The application of the algorithm to a 7-year of CALIOP depolarization ratio mean values revealed patters of seasonal and interannual variability of POC. By comparing the results averaged over the entire study region and entire season for each year separately, we found that the lowest POC occurred in 2013 and the highest POC occurred in 2008.