Appl Opt. 2020 Aug 1;59(22):6702-6716. doi: 10.1364/AO.394123.
Cross-platform observing systems are requisite to capturing the temporal and spatial dynamics of particles in the ocean. We present simultaneous observations of bulk optical properties, including the particulate beam attenuation (c) and backscattering () coefficients, and particle size distributions collected in the North Pacific Subtropical Gyre. Clear and coherent diel cycles are observed in all bulk and size-fractionated optical proxies for particle biomass. We show evidence linking diurnal increases in c and b to daytime particle growth and division of cells, with particles <7µ driving the daily cycle of particle production and loss within the mixed layer. Flow cytometry data reveal the nitrogen-fixing cyanobacterium Crocosphaera (∼4-7µ) to be an important driver of c at the time of sampling, whereas Prochlorococcus dynamics (∼0.5µ) were essential to reproducing temporal variability in b. This study is a step towards improved characterization of the particle size range represented by in situ bulk optical properties and a better understanding of the mechanisms that drive variability in particle production in the oligotrophic open ocean.
跨平台观测系统对于捕捉海洋中粒子的时空动态至关重要。我们呈现了在北太平洋副热带环流中同时观测到的大量光学性质，包括颗粒束衰减（c）和后向散射（b）系数以及颗粒大小分布。所有大量和按粒径分级的光学颗粒生物量代理均观察到清晰一致的昼夜节律。我们证明了 c 和 b 的日变化与细胞的白天生长和分裂有关，粒径<7µm 的颗粒驱动了混合层中颗粒产生和损失的日循环。流式细胞术数据表明，固氮蓝藻 Crocosphaera（∼4-7µm）是采样时 c 的重要驱动因素，而聚球藻的动态（∼0.5µm）对于重现 b 的时间变化至关重要。本研究是朝着更好地表征原位大量光学性质所代表的颗粒尺寸范围以及更好地理解驱动贫营养开阔海洋中颗粒产生变化的机制迈出的一步。
