First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, China.
National Satellite Ocean Application Service, Beijing 100081, China.
Sensors (Basel). 2018 Sep 12;18(9):3067. doi: 10.3390/s18093067.
The out-of-band (OOB) response is one of the key specifications for satellite optical sensors, which has important influences on quantitative remote sensing retrieval. In this paper, the effect of OOB response on the radiometric measurements made just above the sea surface is evaluated for the three broad visible bands (i.e., blue, green, and red) of the Coastal Zone Imager (CZI) onboard China's ocean satellite HY-1C to be launched in September 2018. For the turbid coastal (Case 2) waters whose optical properties are mainly dominated by suspended sediment and colored dissolved organic material, the OOB effect can be neglected (<2%) for all three CZI visible bands. For the phytoplankton-dominated (Case 1) waters which are mainly distributed in the clear open ocean, a significant (>2%) OOB effect was found in the green band over oligotrophic waters (chlorophyll a concentration ≤~0.1 mg/m³), and accordingly a model based on the CZI blue-green band ratio is proposed to correct this effect. The OOB influence on the CZI ocean color retrieval is discussed. This research highlights the importance of the comprehensive pre-launch radiometric characterization and the OOB effect correction for the broad band space-borne sensor, in order to achieve a high-quality quantitative ocean product.
带外响应是卫星光学传感器的关键指标之一，对定量遥感反演有重要影响。本文针对 2018 年 9 月即将发射的中国海洋卫星 HY-1C 上的海岸带成像仪（CZI）的三个宽可见波段（蓝色、绿色和红色），评估了带外响应对海面上方进行辐射测量的影响。对于以悬浮泥沙和有色溶解有机物为主导光学特性的浑浊海岸（案例 2）水域，带外效应对所有三个 CZI 可见波段的影响可以忽略不计（<2%）。对于主要分布在开阔清澈海域的浮游植物主导（案例 1）水域，在贫营养水域（叶绿素 a 浓度≤~0.1mg/m³）的绿光波段发现了显著的（>2%）带外效应，因此提出了一种基于 CZI 蓝绿波段比的模型来校正这种效应。讨论了带外响应对 CZI 海洋颜色反演的影响。这项研究强调了对宽波段星载传感器进行全面的发射前辐射特性描述和带外效应校正的重要性，以实现高质量的定量海洋产品。
