水体流速对现场离水辐射测量的影响

Effect of Current Velocity on Measurement of Field Water Radiation

针对高浊度水域所特有的水文特征对现场离水辐射测量的影响,结合光谱仪不同积分时间提出了一种新的野外测量方法。利用2016年5月、6月2个航次的现场光谱测量数据和同步水文泥沙参数,采用无偏差百分比分析发现,同一采样时刻点,在流速小于1m/s时,各积分时间所测遥感反射率测得值差异范围在3.35%～8.28%;当流速大于1m/s时,二者偏差在10.29%～25.58%。利用表层悬浮泥沙与遥感反射率回归拟合精度检验数据质量,建议在现场测量水体离水辐射时,当水体流速变化范围较大时,使用积分时间34ms测量,采用分组流速法进行悬沙反演,以提高反演结果的准确性。

Because of the influence of hydrological characteristics of specific high turbidity waters on the measurement of above-water radiation,a new field measurement method based on the different integration time of spectroradiometer was proposed.The in-situ spectroradiometry measurement data and the synchronous hydrological sediment parameters of the survey in May and June are analyzed by the mothed of unbiased percent difference.It shows that when the flow rate is less than 1 m/s,the difference between the measured values of remote sensing reflectance is 3.35%~8.28%,and when the flow velocity is more than 1 m/s,the deviation is between 10.29%~25.58%.The accuracy of the data is validated by the surface sedimentation and the remote sensing reflectance regression fitting.It is suggested that when the water flow velocity changes in a larger range,the integration time 34 ms should be taken,and in order to improve the accuracy of inversion result,the method of the group flow velocity should be taken.