Barnes R A, Eplee R E, Patt F S, McClain C R
General Sciences Corporation, Beltsville, Maryland 20705, USA.
Appl Opt. 1999 Jul 20;38(21):4649-64. doi: 10.1364/ao.38.004649.
We report on the lunar and solar measurements used to determine the changes in the radiometric sensitivity of the Sea-viewing Wide Field-of-view Sensor (SeaWiFS). Radiometric sensitivity is defined as the output from the instrument (or from one of the instrument bands) per unit spectral radiance at the instrument's input aperture. Knowledge of the long-term repeatability of the SeaWiFS measurements is crucial to maintaining the quality of the ocean scenes derived from measurements by the instrument. For SeaWiFS bands 1-6 (412-670 nm), the change in radiometric sensitivity is less than 0.2% for the period from November 1997 through November 1998. For band 7 (765 nm), the change is approximately 1.5% and for band 8 (865 nm) approximately 5%. The rates of change of bands 7 and 8, which were linear with time for the first eight months of lunar measurements, are now slowing. The scatter in the data points about the trend lines in this analysis is less than 0.3% for all eight SeaWiFS bands. These results are based on monthly measurements of the moon. Daily solar measurements using an onboard diffuser show that the radiometric sensitivities of the SeaWiFS bands have changed smoothly during the time intervals between lunar measurements. Because SeaWiFS measurements have continued past November 1998, the results presented here are considered as a snapshot of the instrument performance as of that date.
我们报告了用于确定宽视场海洋观测传感器（SeaWiFS）辐射灵敏度变化的月球和太阳测量数据。辐射灵敏度定义为仪器（或仪器的一个波段）在其输入孔径处每单位光谱辐射率的输出。了解SeaWiFS测量的长期可重复性对于维持从该仪器测量中得出的海洋场景质量至关重要。对于SeaWiFS的1 - 6波段（412 - 670纳米），在1997年11月至1998年11月期间，辐射灵敏度的变化小于0.2%。对于7波段（765纳米），变化约为1.5%，对于8波段（865纳米）约为5%。7波段和8波段的变化率在前八个月的月球测量中与时间呈线性关系，现在正在放缓。在该分析中，所有八个SeaWiFS波段的数据点围绕趋势线的离散度小于0.3%。这些结果基于对月球的月度测量。使用机载漫射器进行的每日太阳测量表明，在月球测量的时间间隔内，SeaWiFS各波段的辐射灵敏度变化平稳。由于SeaWiFS的测量在1998年11月之后仍在继续，此处呈现的结果被视为截至该日期的仪器性能快照。
