Diurnal remote sensing of coastal/oceanic waters: a radiometric analysis for Geostationary Coastal and Air Pollution Events.
Diurnal remote sensing of coastal/oceanic waters: a radiometric analysis for Geostationary Coastal and Air Pollution Events.
复制标题
DOI：
10.1364/ao.53.000648
复制
发表时间：
2014-02
期刊：
影响因子：
1.9
通讯作者：
N. Pahlevan;Z. Lee;Chuanmin Hu;J. Schott
中科院分区：
文献类型：
--
作者：
N. Pahlevan;Z. Lee;Chuanmin Hu;J. Schott
对地静止平台上的光学遥感系统可以提供动态沿海/海洋水域生物光学特性的高频观测。从最终用户的角度来看，人们认识到日常科学产品的保真度在很大程度上依赖于成像系统的辐射灵敏度/性能。本研究旨在确定从地球静止轨道昼夜观察到的生物光学特性的理论检测限。该分析基于耦合辐射传输模拟以及为地球静止海岸和空气污染事件 (GEO-CAPE) 任务定义的最低辐射要求。水的光学活性成分的每日检测限，包括叶绿素-a (CHL) 和总悬浮固体 (TSS) 的近表面浓度，以及有色溶解有机物 (aCDOM) 的吸收。对视野 (FOR) 中多个位置的昼夜大气层顶部辐射率 (Lt) 进行建模，以研究不同成像几何形状的辐射灵敏度。结果发现，在海洋水域（CHL = 0.07 mg/m3）中，除了 FOR 边缘的下午晚些时候观测之外，在所有地点和时间检测 CHL 中小于 0.01 mg/m3 的变化都是可行的。对于更具营养性/浑浊度的水域 (0.6<CHL<4.5)，当空气质量分数 (AMF) 小于 5 时，所提出的系统对小于 0.1 mg/m3 的变化（CHL）敏感。对于 aCDOM(440)，检测大于 0.02 m(-1) (0.08<aCDOM(440)<0.36) 的变化对于大多数成像来说是可行的几何形状。这相当于AMF<5。对于 TSS，整个 FOR 期间从清晨到下午晚些时候可检测到大约 ΔTSS=0.1 g/m3 (0.5<TSS<4.5) 的变化。这项研究深入了解了 GEO-CAPE 任务在识别大气层顶部 (TOA) 生物光学特性变化方面的辐射灵敏度，这有助于更清楚地了解与表面产物相关的不确定性。
Optical remote sensing systems aboard geostationary platforms can provide high-frequency observations of bio-optical properties in dynamical coastal/oceanic waters. From the end-user standpoint, it is recognized that the fidelity of daily science products relies heavily on the radiometric sensitivity/performance of the imaging system. This study aims to determine the theoretical detection limits for bio-optical properties observed diurnally from a geostationary orbit. The analysis is based upon coupled radiative transfer simulations and the minimum radiometric requirements defined for the GEOstationary Coastal and Air Pollution Events (GEO-CAPE) mission. The diurnal detection limits are found for the optically active constituents of water, including near-surface concentrations of chlorophyll-a (CHL) and total suspended solids (TSS), and the absorption of colored dissolved organic matter (aCDOM). The diurnal top-of-atmosphere radiance (Lt) is modeled for several locations across the field of regard (FOR) to investigate the radiometric sensitivity at different imaging geometries. It is found that, in oceanic waters (CHL=0.07 mg/m3), detecting changes smaller than 0.01 mg/m3 in CHL is feasible for all locations and hours except for late afternoon observations on the edge of the FOR. For more trophic/turbid waters (0.6<CHL<4.5), the proposed system is found sensitive to changes (in CHL) smaller than 0.1 mg/m3 when the air mass fraction (AMF) is less than 5. For aCDOM(440), detecting the changes larger than 0.02 m(-1) (0.08<aCDOM(440)<0.36) is found feasible for most of the imaging geometries. This is equivalent to AMF<5. For TSS, changes on the order of ΔTSS=0.1 g/m3 (0.5<TSS<4.5) are detectable from early morning to late afternoon across the entire FOR. This study gives insights into the radiometric sensitivity of the GEO-CAPE mission in identifying the changes in bio-optical properties at top-of-atmosphere (TOA), which aids in a more lucid understanding of the uncertainties associated with the surface products.