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, Rrs(λ)）主要用于机载与星载海洋色遥感测量的验证工作。反演模型同样会依托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、漂浮植被的监测与识别。石油的存在同样会改变水体的镜面反射特性，进而影响实测的Rrs结果。研究人员通常通过船舶平台，采用手持式光谱辐射计（handheld spectroradiometer）开展Rrs(λ)的测量：借助具备有限视场的光谱辐射计，可对水体表面反射光、部分天空光以及经校准的漫反射参考板（diffuse reflectance reference plaque）的辐射亮度进行多次重复测量。Rrs(λ)的测量在太阳高度角适中时可靠性最高，且观测角度需符合遥感观测规范。在Rrs(λ)的计算过程中，需将多组辐射亮度测量结果进行融合处理。