海洋B星水色仪辐射基准异常分析及修复算法研究

Analysis of radiation reference anomaly of HY-1B COCTS and research on the repair algorithm

水色遥感产品的三要素为:叶绿素、悬浮物质和黄色物质。水色水温扫描仪(简称水色仪)作为海洋一号卫星的主载荷之一,设置了8个可见近红外探测通道,主要目的是获取全球的海色三要素分布产品,为全球海洋初级生产力分布研究提供数据。2007年发射的HY-1B星水色仪,作为零辐射基准的冷空位置在入轨初期即存在光污染,导致近红外探测通道深海水域信号出现截止,并且纬度越低冷空信号越大。为了研究此问题的存在机理并对B星水色仪的历史数据进行修复,在实验室对问题产生源的特性进行了验证,并对其影响机理进行了分析。通过获取C星水色仪耀光能量与太阳天顶角的关系,计算B星水色仪在不同太阳天顶角的耀光能量。根据辐射定标系数可得到耀光能量对应的信号码值和码值修复量。结果表明,该修复值与由太阳天顶角计算得到的能量成线性关系,并可用于对B星水色仪其他目标信号进行修复。该算法可用于对B星水色仪近9年的遥感数据的修复,为后续与同类海洋遥感仪器的数据比对并反演水色产品奠定了理论基础。

The three elements of water color remote sensing products are chlorophyll,suspended substance and yellow substance.As one of the main loads of HY-1 satellite,Chinese Ocean Color and Temperature Scanner(COCTS)has set up 8 visible and near-infrared detection channels,to provide primary data for the study of global ocean primary productivity distribution.HY-1B COCTS was launched in 2007,and at the beginning of orbit entry there exists light pollution in cold space which works as the zero-radiation datum,which leads to the signal cut-off in the deep-sea area of the nearinfrared detection channel,and the lower the latitude,the bigger the cold air signal is.In order to study the mechanism of the problem and repair the historical data of HY-1B COCTS,the characteristics of the source of the problem was verified in the laboratory,and the influence mechanism was analyzed.Based on the relationship between the sun glint energy of HY-1C COCTS and the solar zenith angle,the sun glint energy of HY-1B COCTS at different solar zenith angle is calculated.According to the radiometric calibration coefficient,the corresponding code value of the sun glint energy and the correction quantity can be obtained.The results show that the correction quantity is linear with the energy calculated from the solar zenith angle,and can be used to repair other target signals of HY-1B COCTS.This algorithm can be used to repair the remote sensing data of nearly 9 years of HY-1B COCTS.It lays a theoretical foundation for data comparison between the same kind of ocean remote sensing instrument and retrieving water color products.