RadCalNet: A Radiometric Calibration Network for Earth Observing Imagers Operating in the Visible to Shortwave Infrared Spectral Range
RadCalNet: A Radiometric Calibration Network for Earth Observing Imagers Operating in the Visible to Shortwave Infrared Spectral Range
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DOI：
10.3390/rs11202401
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发表时间：
2019-10-01
期刊：
影响因子：
5
通讯作者：
Woolliams, Emma R.
中科院分区：
文献类型：
--
作者：
Bouvet, Marc;Thome, Kurtis;Woolliams, Emma R.
使用原位测量的替代校准方法在 20 世纪 80 年代初首次使用，此后不断改进，以跟上正在校准的传感器的辐射要求的发展步伐。用于替代校准的原位测量的优点是它们可以以可追溯和可量化的精度进行，这使得它们成为在轨传感器的一致性研究的理想选择。最近用于收集原位数据的自动化站点的发展导致用于传感器校准的可用数据集数量的增加。目前的工作描述了辐射校准网络（RadCalNet），该网络致力于提供自动化的表面和大气原位数据，作为包括多个站点的网络的一部分，用于在可见光到短波红外光谱范围内进行光学成像仪辐射校准。 RadCalNet 的主要目标是标准化收集数据的协议、处理大气层顶部反射率，并为可追溯至国际单位制的自动化站点提供不确定性预算。 RadCalNet 是地球观测卫星委员会 (CEOS) 校准和验证工作组 (WGCV) 和红外可见光传感器 (IVOS) 下的 RadCalNet 工作组努力的成果。这里介绍了位于美国、法国、中国和纳米比亚的四个辐射校准仪器站点，它们被用作原型设计和演示 RadCalNet 的初始站点。所有四个站点都依赖于收集数据来评估该站点的表面反射率以及大气数据。数据在 RadCalNet 内转换为大气层顶部反射率，并通过门户网站提供，以允许用户进行辐射校准或验证其感兴趣的传感器的校准。对于最低点观察几何结构，在 400 nm 至 1000 nm 光谱范围内，每隔 30 分钟即可获得具有相关不确定性的大气顶部反射率数据，间隔为 10 nm。示例展示了如何使用来自 RadCalNet 的大气顶层数据来确定两个传感器之间的一致性。
Vicarious calibration approaches using in situ measurements saw first use in the early 1980s and have since improved to keep pace with the evolution of the radiometric requirements of the sensors that are being calibrated. The advantage of in situ measurements for vicarious calibration is that they can be carried out with traceable and quantifiable accuracy, making them ideal for interconsistency studies of on-orbit sensors. The recent development of automated sites to collect the in situ data has led to an increase in the available number of datasets for sensor calibration. The current work describes the Radiometric Calibration Network (RadCalNet) that is an effort to provide automated surface and atmosphere in situ data as part of a network including multiple sites for the purpose of optical imager radiometric calibration in the visible to shortwave infrared spectral range. The key goals of RadCalNet are to standardize protocols for collecting data, process to top-of-atmosphere reflectance, and provide uncertainty budgets for automated sites traceable to the international system of units. RadCalNet is the result of efforts by the RadCalNet Working Group under the umbrella of the Committee on Earth Observation Satellites (CEOS) Working Group on Calibration and Validation (WGCV) and the Infrared Visible Optical Sensors (IVOS). Four radiometric calibration instrumented sites located in the USA, France, China, and Namibia are presented here that were used as initial sites for prototyping and demonstrating RadCalNet. All four sites rely on collection of data for assessing the surface reflectance as well as atmospheric data over that site. The data are converted to top-of-atmosphere reflectance within RadCalNet and provided through a web portal to allow users to either radiometrically calibrate or verify the calibration of their sensors of interest. Top-of-atmosphere reflectance data with associated uncertainties are available at 10 nm intervals over the 400 nm to 1000 nm spectral range at 30 min intervals for a nadir-viewing geometry. An example is shown demonstrating how top-of-atmosphere data from RadCalNet can be used to determine the interconsistency between two sensors.