Near surface fluorescence and optical scattering profiles at CTD sampling stations. Cruises DP01 and DP02 from May 2015 - August 2015

Optical absorption and scattering are the primary determinants of the flow of radiant energy in the ocean’s surface waters. Particles in the water are the principle source of scattering, and the scattering measurements can indicate the amount and/or type of particles present. While a complete measurement of the scattered light field is complex and cumbersome, a measurement of the backscattering at particular angles can usually be related to the total backscattering of light. The backscattering of light not only provides information about the particle present, it is important for understanding variations in Rrs. Backscattering in the water was measured with a Hobilabs HS6 6 channel scattering meter. This viewed backscattered light at wavelengths of 442, 488,532,589,620, 680nm, and at a viewing angle of ~140°. The HS6 was synchronized with a chlorophyll and CDOM fluorometer, and both instruments were lowered on an instrument frame through the upper portion of the water column to obtain vertical profiles of the in situ chl. and CDOM fluorescence, as well as the amount and spectral shape of the backscattering. These profiles were at the CTD sampling stations, but instrument constraints limit the depth of the profiles to 200m or less. This data was collected during the same cruise as GRIIDC CTD datasets R4.x257.230:0004 and R4.x257.230:0010