大太阳天顶角下水色卫星叶绿素遥感探测能力研究

Research on chlorophyll detection ability under high solar zenith angle

本文利用考虑地球曲率的矢量辐射传输模型PCOART-SA,对大太阳天顶角下叶绿素浓度的卫星遥感探测极限能力进行了模拟研究。结果表明:太阳-传感器几何参数,尤其是太阳天顶角对叶绿素浓度变化的探测极限能力影响较大;大太阳天顶角下,卫星对叶绿素浓度变化的探测能力下降十几倍。在典型陆架水体(叶绿素浓度为1μg/L),低太阳天顶角(30°)时,叶绿素浓度变化探测极限为0.012 8μg/L(约为原浓度的1.2%),而大太阳天顶角(80°)时,探测极限为0.136μg/L(约为原浓度的13.6%)。相比于太阳天顶角,观测天顶角增大造成的叶绿素浓度探测能力衰减较小。叶绿素浓度越高,吸收作用越强,对卫星遥感器的辐射探测灵敏度、定标及大气校正精度的要求越高。

The detection limit of satellite chlorophyll algorithm at large solar zenith angles(SZA)in polar regions was assessed using the vector radiative transfer model of PCOART-SA which has accounted for the spherical-shell atmosphere.It was found that the geometric parameters between sun and sensor,particularly the solar zenith angle,have significant influence in the detection limit of satellite chlorophyll algorithm.The minimum chlorophyll concentration detected by satellite is about 0.136μg/L at large SZA of 80°,while the minimum value is 0.012 8μg/L at 30°.Because of the high absorption resulted by chlorophyll,the satellite detection at large SZA is difficult,and thus requires high radiometric sensitivity sensor,more accurate calibration and atmospheric correction.