报告题目一：气候预报中的信噪比悖论
报 告 人 ：张威，普林斯顿大学&NOAA GFDL 研究员
报告人简介：张威，普林斯顿大学&NOAA GFDL 研究员，NOAA GSL (Global System Lab)访问研究员，主要从事从次季节到年代际尺度的气候动力学及预报研究。
报告摘要：最新的研究表明，信噪比悖论在季节到年代际尺度的气候预测中普遍存在。该悖论的实质是模型中的信噪比可能过小而难以模拟观测中的实际信号，并且模型对观测的预测可能比其预测本身更好。由于先前的研究可能低估了模型可预测性，因此信噪比悖论突出了模型预测中的潜在问题。本文的重点有两个方面：第一个目的是在CMIP5模型的背景下，从信噪比悖论的角度重新评估年代际可预测性。结果表明，CMIP5模型中的年代际可预测性通常被低估，这可能是由于信噪比悖论的存在造成的。模型低估了可能存在悖论地区的年代际可预测性，尤其是在热带大西洋和热带印度洋以及涡流丰富的地区，包括墨西哥湾流、黑潮洋流和南大洋。基于第一个目标的结果，第二个目的是确定这种年代际可预测性的低估至少部分是由于CMIP5模型缺少海洋中尺度涡流过程。我们使用涡流解析和涡流参数化海洋模型进行了一系列耦合模型实验。结果表明，与涡流参数化模型相比，涡流解析模型减少了信噪比悖论出现的可能性，尤其是在中尺度涡流丰富的地区，而这些地区恰好也是年代际可预测性提高的地区。我们认为在该地区这种可预测性的增强是由于海洋中垂直连通性的增强。中尺度海洋特征和相关的垂直连通性的存在显著影响年代际变化、可预测性以及信噪比悖论。
报告题目二：In situ hyperspectral characteristics and the discriminative ability of remote sensing to coral species in the South China Sea
报 告 人 ：曾凯，LTO光学组博士研究生
报告人简介：曾凯，LTO光学组博士研究生，主要从事浅水光学特性，海洋环境光学观测等方面的研究。目前专注于海洋光学实验任务，负责应用现场数据和模型模拟来研究海洋环境中的辐射传输过程，并协助参与海洋环境监测设备的开发和应用。
报告摘要：Knowledge about the optical features of benthic objects is essential for quantifying spectral signatures, remote sensing-based mapping, and ecological monitoring in coral reefs. We explored and discriminated spectral characteristics from three classified hierarchies, the typical substrates of community groups, families of coral, and species of coral, based on in situ hyperspectral datasets. In situ full-resolution (1-nm) spectra provided the best discrimination ability with mean accuracies of 97.5%, 90.9%, and 91.6% for typical substrates, coral families, and coral species, respectively. The spectral abilities of remote sensors were assessed by applying the spectral response functions of three multispectral sensors (Landsat 8 OLI, Sentinel-2A, and World View-2) to the full-resolution spectra. Discrimination analyses of the simulated spectra demonstrated that the spectral separations of typical substrates might be apparent, with overall classification accuracies of 89.6%, 88.2%, and 90.4% for the Landsat 8 OLI, Sentinel-2A, and World View-2 sensors, respectively. The discrimination analyses of families and species produced overall classification accuracies of 67.1% and 69.6%, respectively, for the Landsat 8 OLI, 56.0% and 56.0% for the Sentinel-2A sensor, and 64.5% and 61.8% for the World View-2 sensor. We conclude that it is practical to classify various substrate targets in communities and taxonomic coral groups using in situ hyperspectral reflectance data. This conclusion contradicts previous reports that recognizing corals at the species level by their optical signatures is unlikely. Furthermore, multispectral sensors are currently inadequate for spectrally separate corals. Nevertheless, spectral separations may be possible for different substrate targets with visual spectral differences. Our results serve as general guidelines for detecting benthic species living in coral reefs using remote sensors.
报告时间：2021年9月17日（周五）上午 09:00
报告地点：2号楼1201会议室
腾讯会议ID（线上报告）：269 724 474 ;
主持人：吴正超 副研究员 ，牛建伟 助理研究员
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