Development and validation of the CALIPSO ocean subsurface data

Abstract

CALIOP, the dual wavelength, polarization sensitive lidar flying aboard the CALIPSO satellite, has been operating since June 2006 and is expected to continue beyond 2017. CALIOP's depolarization ratio is one of the best calibrated measurements from space. Over the life of the CALIPSO mission, the stability of the CALIOP depolarization ratio calibration has remained within 1%. CALIOP's highly stable depolarization ratio measurements can be used for studying changes in phytoplankton backscatter and carbon biomass (Behrenfeld et al., 2013). Using the depolarization ratio measurements from CALIOP together with collocated A-Train measurements (such as the ocean surface backscatter cross section derived from CloudSat ocean surface backscatter measurements, AMSRE/AMSR-2 wind speeds, and MODIS diffuse attenuation coefficients), we have developed innovative retrieval methods that translate the CALIOP ocean subsurface signals into the following optical and physical properties (Behrenfeld et al., 2013; Lu et al., 2014; Hu et al., 2015): · the cross polarization component of the column integrated ocean subsurface backscatter signal; · the particulate backscatter coefficient (bbp); · the depolarization ratio of ocean subsurface backscatter; and · the ocean subsurface beam attenuation coefficient. These new CALIOP data products can provide a wealth of unique information to complement existing ocean color measurements, including nighttime measurements, measurements underneath aerosols and non-opaque clouds, measurements in polar regions during all seasons and near sea-ice, and direct measurements of beam attenuation coefficients.