Video Plankton Recorder data from R/V Columbus Iselin, R/V Endeavor cruises CI9407, EN259, and EN262 in the Gulf of Maine and Georges Bank from 1994-1995 (GB project)
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<p>This dataset includes ALL the abundance values, zero and non-zero. The data files are very large. In order to map the VPR data, see the VPR_ashjian_nonzero [<a href=\"http://globec.whoi.edu/jg/serv/globec/gb/vpr_cashjian_nonzero.html0\" target=\"_blank\">http://globec.whoi.edu/jg/serv/globec/gb/vpr_cashjian_nonzero.html0</a>]. In the 'nonzero' dataset, values of 0 in the abund_L column (taxon abundance) have been removed.</p> <p>For an alternate display, including both zero and non-zero data, see VPR_ashjian_alt [<a href=\"http://globec.whoi.edu/jg/serv/globec/gb/vpr_cashjian_read.html0\" target=\"_blank\">http://globec.whoi.edu/jg/serv/globec/gb/vpr_cashjian_read.html0</a>].</p> <p><strong>Methodology</strong><br /> The following information was extracted from <em>C.J. Ashjian et al., Deep- Sea Research II 48(2001) 245-282 </em>. An in-depth discussion of the data and sampling methods can be found there.</p> <p>The Video Plankton Recorder was towed at 2 m/s, collecting data from the surface to the bottom (towyo). The VPR was equipped with 2-4 cameras, temperature and conductivity probes, fluorometer and transmissometer. Environmental data was collected at 0.25 Hz (CI9407) or 0.5 Hz (EN259, EN262). Video images were recorded at 60 fields per second (fps).</p> <p>Video tapes were analyzed for plankton abundances using a semi-automated method discussed in <em>Davis, C.S. et al., Deep-Sea Research II 43 (1996) 1946-1970</em>. In-focus images were extracted from the video tapes and identified by hand to particle type, taxon, or species. Plankton and particle observations were merged with environmental and navigational data by binning the observations for each category into the time intervals at which the environmental data were collected (again see above <em>Davis</em> citation). Concentrations were calculated utilizing the total volume (liters) imaged during that period. For less-abundant categories, usually only a single organism was observed during each time interval so that the resulting concentrations are close to presence or absence data rather than covering a range of values.</p>
<p>本数据集涵盖所有丰度数值，包括零值与非零值。数据文件体积较大。如需映射该视频浮游生物记录仪（Video Plankton Recorder，VPR）数据，请参考VPR_ashjian_nonzero [<a href="http://globec.whoi.edu/jg/serv/globec/gb/vpr_cashjian_nonzero.html0" target="_blank">http://globec.whoi.edu/jg/serv/globec/gb/vpr_cashjian_nonzero.html0</a>]。在该「非零值」数据集中，abund_L列（类群丰度）中的零值已被移除。</p><p>如需查看包含零值与非零值数据的备用可视化结果，请参考VPR_ashjian_alt [<a href="http://globec.whoi.edu/jg/serv/globec/gb/vpr_cashjian_read.html0" target="_blank">http://globec.whoi.edu/jg/serv/globec/gb/vpr_cashjian_read.html0</a>]。</p><p><strong>研究方法</strong><br />以下信息源自C.J. Ashjian等人发表于《Deep-Sea Research II》第48卷（2001年）第245-282页的研究，该文献对数据与采样方法进行了详尽探讨。</p><p>该视频浮游生物记录仪（VPR）以2 m/s的速度拖曳采样，采集从表层至海底的相关数据（towyo）。VPR搭载2-4台摄像机、温度电导率传感器、荧光计与透射率计。环境数据采集频率为0.25 Hz（CI9407）或0.5 Hz（EN259、EN262），视频图像以每秒60帧（fps）的速率录制。</p><p>研究人员采用Davis C.S.等人于《Deep-Sea Research II》第43卷（1996年）第1946-1970页中提及的半自动分析方法，对录像带中的浮游生物丰度进行统计。首先从录像带中提取清晰对焦的图像，再通过人工识别确定颗粒类型、类群或物种。随后将浮游生物与颗粒观测数据与环境及导航数据进行整合：将各分类的观测结果按环境数据采集的时间区间进行分箱处理（详见上述Davis文献的引用说明），并通过该时段内成像的总容积（升）计算浮游生物浓度。对于丰度较低的类群，通常每个时间区间内仅能观测到单个生物体，因此得到的浓度数据近似于存在/不存在数据，而非覆盖一定范围的连续数值。</p>
