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, and 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 chlorophyll 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 limited the depth of the profiles to 200 m or less. This data was collected during the same cruises as GRIIDC CTD datasets R4.x257.230:0004 (DP01, R/V Point Sur PS1505, https://doi.org/10.7266/N73R0QSX) and R4.x257.230:0010 (DP02, R/V Point Sur PS1606, https://doi.org/10.7266/N7PV6HS1).

光吸收与散射是海洋表层水体中辐射能传输的核心决定因素。水体中的颗粒物是散射的主要来源，散射测量可反映水体中现存颗粒物的数量与/或类型。尽管完整测量散射光场的过程复杂且繁琐，但特定角度下的后向散射测量通常可与总后向散射光建立关联。后向散射光不仅可提供水体中现存颗粒物的相关信息，同时对于理解Rrs（遥感反射率，Remote sensing reflectance）的变化具有重要意义。水体后向散射采用Hobilabs HS6型6通道散射仪进行测量，该仪器可在442、488、532、589、620及680nm波长下，以及约140°的观测角度下采集后向散射光信号。HS6散射仪与叶绿素及CDOM（有色可溶性有机物，Colored Dissolved Organic Matter）荧光计同步部署，两台仪器均通过安装架下放至水体上层，以获取原位叶绿素与CDOM荧光、后向散射强度及其光谱形态的垂直剖面数据。上述垂直剖面数据采集于CTD（温盐深仪，Conductivity Temperature Depth）采样站位，但受仪器性能限制，剖面最大水深不超过200米。本数据集与GRIIDC的CTD数据集R4.x257.230:0004（DP01，R/V Point Sur PS1505，https://doi.org/10.7266/N73R0QSX）及R4.x257.230:0010（DP02，R/V Point Sur PS1606，https://doi.org/10.7266/N7PV6HS1）采集于同一科考航次。