Spectral remote sensing reflectance of the water surface collected at multiple stations on cruises DP03 and DP04, May-August 2016

Remote sensing reflectance, Rrs(λ), is used for validation of airborne and satellite ocean color measurements. Inverse models also employ Rrs measurements to estimate the bio-optical properties of near-surface waters or shallow benthic environments. It has been used to detect algal blooms, floating vegetation. The presence of oil also alters the water’s specular reflectance properties, and thus the measured Rrs. Rrs(λ) is measured from the ship using a handheld spectroradiometer. Multiple measurements of the light reflected from the water’s surface, a portion of the sky, and a calibrated, diffuse reflectance reference plaque are made using a spectroradiometer with a limited field of view. The Rrs measurement is most reliable during moderate solar elevations, using observational angles consistent with remote sensing protocols. Multiple radiance measurements are combined in the computation of Rrs(λ).遥感反射率（Remote Sensing Reflectance，缩写Rrs(λ)）主要用于航空与卫星海洋水色测量的精度验证。逆模型（Inverse Models）同样会依托Rrs测量数据，估算近表层水体或浅海底栖环境的生物光学特性。该指标已被应用于藻华与漂浮植被的监测工作。石油的存在会改变水体的镜面反射（specular reflectance）特性，进而影响实测Rrs的数值。科研人员可在船舶平台上，使用手持式光谱辐射计（handheld spectroradiometer）开展Rrs(λ)的测量：采用视场角受限的光谱辐射计（spectroradiometer），对水体表面反射光、部分天空光以及经过校准的漫反射参考板（diffuse reflectance reference plaque）分别进行多次辐射亮度测量。当太阳高度角适中，且观测角度符合遥感观测规范（remote sensing protocols）时，Rrs的测量结果最为可靠。最终通过多组辐射亮度测量值的融合计算，即可得到Rrs(λ)的数值。