Hyperspectral absorption coefficient measurements during the cruise HE503 with RV HEINCKE

This dataset was collected during the cruise HE503 (22.02.2018 - 01.03.2018) with RV HEINCKE from Bremerhaven, Germany to Bremerhaven, Germany. It contains absorption coefficients [m-1] from water constituents in a range of 400 to 710 nm (2 nm resolution). In total, 24 stations have been sampled. Where the water column was mixed, one sample was taken from approx. 5 m. In case of stratified water or chlorophyll-a maxima present, additional samples from greater depths were taken. The water samples were fractionated by filtration to investigate the absorption with respect to size classes. Thus, data from unfiltered samples are available as well as data from water that passed a 20 µm, 2 µm, and 0.2 µm filter, respectively (denoted as a_tot, a_20µm, a_2µm, and a_cdom). The absorption coefficient measurements were performed with a point-source integrating-cavity absorption meter (PSICAM) with a sample volume of approx. 400 ml. The specifications of the PSICAM, relevant publications, information regarding the measurements, calibration of the instrument, and data correction are provided in a separate document. Raw data are available on request from the authors.Chief Scientist of HE503: Dr. Thomas H. Badewien / Dr. Jochen Wollschläger , Institute for Chemistry and Biology of the Marine Environment (ICBM)Work related to Coastal ocean darkening - Light availability in the past and future marine environment (COD)

本数据集采集于HE503科考航次（2018年2月22日至2018年3月1日），搭载科考船为“海因克号（RV HEINCKE）”，航行往返于德国不来梅哈芬港。数据集包含400~710 nm波段范围内（分辨率2 nm）的水体组分吸收系数[单位：m⁻¹]。本次航次共布设24个采样站位：当水体柱混合均匀时，仅于约5 m水深处采集1份样品；若水体存在层结或出现叶绿素a峰值，则需额外采集更深层的水样。
所有水样通过过滤操作进行分级处理，以探究不同粒径组分的吸收特性，因此既提供未过滤水样的相关数据，也提供分别通过20 µm、2 µm及0.2 µm滤膜的水样数据，分别记为a_tot、a_20µm、a_2µm与a_cdom。
吸收系数的测定采用点源积分腔吸收光度计（point-source integrating-cavity absorption meter, PSICAM）完成，单份样品体积约为400 ml。该仪器的技术规格、相关发表文献、测量说明、仪器校准方法及数据校正流程详见独立文档。原始数据可应要求向作者索取。
HE503航次首席科学家为托马斯·H·巴德维恩博士与约亨·沃尔施莱格尔博士，依托单位为海洋环境化学与生物学研究所（Institute for Chemistry and Biology of the Marine Environment, ICBM）。本数据集关联研究课题为“近岸海洋变暗——过去与未来海洋环境中的光有效性（Coastal ocean darkening - Light availability in the past and future marine environment, COD）”。