SBC LTER: Time series of quarterly NetCDF files of kelp biomass in the canopy from Landsat 5, 7 and 8, since 1984 (ongoing)

This data file represents a time series of canopy area of giant kelp, Macrocystis pyrifera, and bull kelp, Nereocystis luetkeana, and canopy biomass of giant kelp derived from Landsat 5 Thematic Mapper (TM), Landsat 7 Enhanced Thematic Mapper Plus (ETM+), and Landsat 8 Operational Land Imager (OLI) satellite imagery, along with relevant metadata. The kelp canopy is composed of the portions of fronds and stipes floating on the surface of the water. Canopy area (m2) data are given for individual 30 x 30 meter pixels for all coastal areas of Baja California, Mexico, California, Oregon, and Washington, including offshore islands. Biomass data (wet weight, kg) are given for individual 30 x 30 meter pixels in the coastal areas extending from near Ano Nuevo, CA through the southern range limit in Baja California (including offshore islands), representing the range where giant kelp is the dominant canopy forming species. Data were derived from the three Landsat sensors listed above. Observations are made on a 16 day repeat cycle, for each instrument, but the temporal coverage is irregular because of cloud cover, instrument failure, and the mission length of each sensor (TM: 1984 – 2011, ETM+: 1999 – present, OLI: 2013 – present). Estimates of canopy area are derived from the fractional cover of kelp canopy determined from satellite surface reflectance. Estimates of kelp canopy biomass are derived from the relationship between giant kelp fractional cover determined from satellite surface reflectance and empirical measurements of giant kelp canopy biomass in long-term SBC LTER study plots obtained using SCUBA. The different Landsat sensors were calibrated to each other using simulated Landsat data derived from hyperspectral imagery. Missing data due to the ETM+ scan line corrector error were filled using a synchrony-based gap filling method. Data are organized into a single NetCDF file and contain the quarterly area and biomass means for each Landsat pixel across the three sensors. Relevant metadata such as number of Landsat estimates from which the mean was derived, the number of estimates from each sensor, standard error for each quarterly estimate, spatial coordinates, and date are all included in the file. For assistance with the data, please contact [e-mail].

本数据集文件包含由Landsat 5专题制图仪（Thematic Mapper, TM）、Landsat 7增强型专题制图仪Plus（Enhanced Thematic Mapper Plus, ETM+）以及Landsat 8陆地成像仪（Operational Land Imager, OLI）卫星影像提取的巨藻（Macrocystis pyrifera）和公牛藻（Nereocystis luetkeana）冠层面积，以及巨藻冠层生物量时间序列数据，同时附带相关元数据。
海藻冠层指漂浮于水面的藻体叶片和柄部区域。
冠层面积（单位：平方米）数据以30×30米像素为单位，覆盖墨西哥下加利福尼亚州、加利福尼亚州、俄勒冈州和华盛顿州的所有沿岸海域，包括近海岛屿。
生物量数据（湿重，单位：千克）同样以30×30米像素为单位，覆盖范围从加利福尼亚州阿尼奥新诺附近向南至下加利福尼亚州的巨藻优势分布南界（含近海岛屿），该区域以巨藻为主要冠层形成物种。
本数据由上述三款Landsat传感器提取。
各传感器的观测重访周期为16天，但受云层覆盖、传感器故障及各传感器任务时长影响（TM：1984–2011年；ETM+：1999年至今；OLI：2013年至今），时间覆盖范围并不规则。
冠层面积估算基于卫星地表反射率反演得到的海藻冠层覆盖比例。
巨藻冠层生物量估算则结合了卫星地表反射率反演的巨藻覆盖比例，与通过水肺潜水在长期SBC LTER样地中实测的巨藻冠层生物量之间的关联关系。
不同Landsat传感器间的交叉校准通过高光谱影像模拟的Landsat数据完成。
针对ETM+扫描线校正器误差导致的数据缺失，采用基于同步性的间隙填充方法进行补全。
数据集以单个NetCDF文件组织，包含三款传感器各Landsat像素的季度面积与生物量均值。
文件中同时附带相关元数据，包括计算均值所用的Landsat有效估算次数、各传感器的估算次数、各季度估算值的标准误、空间坐标及日期信息。
如需获取数据协助，请联系[e-mail]。