VNREDSat-1 is the first Vietnamese satellite enabling the survey of environmental parameters, such as vegetation and water coverages or surface water quality at medium spatial resolution (from 2.5 to 10 m depending on the considered channel). The New AstroSat Optical Modular Instrument (NAOMI) sensor on board VNREDSat-1 has the required spectral bands to assess the suspended particulate matter (SPM) concentration. Because recent studies have shown that the remote sensing reflectance, Rrs(λ), at the blue (450–520 nm), green (530–600 nm), and red (620–690 nm) spectral bands can be assessed using NAOMI with good accuracy, the present study is dedicated to the development and validation of an algorithm (hereafter referred to as V1SPM) to assess SPM from Rrs(λ) over inland and coastal waters of Vietnam. For that purpose, an in-situ data set of hyper-spectral Rrs(λ) and SPM (from 0.47 to 240.14 g·m−3) measurements collected at 205 coastal and inland stations has been gathered. Among the different approaches, including four historical algorithms, the polynomial algorithms involving the red-to-green reflectance ratio presents the best performance on the validation data set (mean absolute percent difference (MAPD) of 18.7%). Compared to the use of a single spectral band, the band ratio reduces the scatter around the polynomial fit, as well as the impact of imperfect atmospheric corrections. Due to the lack of matchup data points with VNREDSat-1, the full VNREDSat-1 processing chain (atmospheric correction (RED-NIR) and V1SPM), aiming at estimating SPM from the top-of-atmosphere signal, was applied to the Landsat-8/OLI match-up data points with relatively low to moderate SPM concentration (3.33–15.25 g·m−3), yielding a MAPD of 15.8%. An illustration of the use of this VNREDSat-1 processing chain during a flooding event occurring in Vietnam is provided.

中文翻译：

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评估越南沿海和内陆水域遥感悬浮颗粒物的简单经验带比算法：在 VNREDSat-1/NAOMI 传感器中的应用

VNREDSat-1 是越南第一颗能够以中等空间分辨率（从 2.5 到 10 m，取决于所考虑的通道）调查环境参数，例如植被和水覆盖率或地表水质量的卫星。VNREDSat-1 上的新型 AstroSat 光学模块化仪器 (NAOMI) 传感器具有评估悬浮颗粒物 (SPM) 浓度所需的光谱带。因为最近的研究表明，可以使用 NAOMI 评估蓝色 (450-520 nm)、绿色 (530-600 nm) 和红色 (620-690 nm) 光谱带的遥感反射率 Rrs(λ)良好的准确性，本研究致力于开发和验证算法（以下称为 V1SPM）来评估来自越南内陆和沿海水域的 Rrs(λ) 的 SPM。为了这个目的，已经收集了在 205 个沿海和内陆站收集的高光谱 Rrs(λ) 和 SPM（从 0.47 到 240.14 g·m-3）测量的原位数据集。在包括四种历史算法​​在内的不同方法中，涉及红绿反射比的多项式算法在验证数据集上表现最佳（平均绝对百分比差异 (MAPD)​​ 为 18.7%）。与使用单个光谱带相比，带比减少了多项式拟合周围的散射，以及不完美的大气校正的影响。由于缺乏与 VNREDSat-1 的匹配数据点，完整的 VNREDSat-1 处理链（大气校正 (RED-NIR) 和 V1SPM）旨在从大气顶信号估计 SPM，应用于具有相对低至中等 SPM 浓度 (3.33–15.25 g·m-3) 的 Landsat-8/OLI 匹配数据点，产生 15.8% 的 MAPD。提供了在越南发生的洪水事件期间使用此 VNREDSat-1 处理链的说明。