Optical identification, classification and quantification of different oil slicks play important roles in oil-slick monitoring and detection. Under the actions of wind, waves and other marine forces, oil slicks on the sea surface mix with seawater to form oil-seawater emulsions. Herein, we focus on the spectral radiative properties of seawater-in-oil emulsions in the visible-infrared region. The complex refractive indices of crude oil are precisely measured using the combined ellipsometry-transmission method, after which the radiative properties of seawater droplets embedded in crude oil and seawater-in-oil emulsions obtained using the traditional and improved Lorenz-Mie theory are compared and analyzed to illustrate the effects of the absorption of host medium. The directional-hemispherical emittance and reflectance for seawater-in-oil emulsions are calculated using the Monte Carlo method. Results show that even though the traditional Mie-calculated radiative properties deviate obviously from the improved Lorenz-Mie theory results, directional-hemispherical reflectance and emittance of seawater-in-oil emulsions show relatively small difference. Besides, increasing the droplet volume fraction and film thickness may generally lead to enhanced scattering of seawater droplets, further leading to enhanced light reflection and reduced light emission. With the increase in both droplet size and absorption index of seawater and crude oil, the effects of seawater droplet absorption and oil absorption on overall attenuation of emulsions increase considerably; they may weaken the reflection and strengthen the emission. Obtaining the key radiative parameters of different oil species and oil emulsions will be helpful for promoting the practical application of quantitative optical remote sensing of oil slicks on sea surface.

不同油层的光学识别、分类和量化在油层监测和检测中起着重要作用。在风、浪等海洋力的作用下，海面浮油与海水混合形成油-海水乳状液。在这里，我们专注于油包海水乳液在可见红外区域的光谱辐射特性。结合椭偏-透射法精确测量原油的复折射率，然后比较了嵌入原油中的海水液滴和使用传统和改进的洛伦兹-米理论获得的油包海水乳液的辐射特性，分析以说明宿主介质吸收的影响。使用蒙特卡罗方法计算油包海水乳液的定向半球发射率和反射率。结果表明，尽管传统的 Mie 计算辐射特性与改进的 Lorenz-Mie 理论结果存在明显偏差，但油包海水乳液的定向半球反射率和发射率差异较小。此外，增加液滴体积分数和薄膜厚度通常会导致海水液滴的散射增强，进一步导致光反射增强和光发射减少。随着海水和原油的液滴尺寸和吸收指数的增加，海水液滴吸收和吸油对乳液整体衰减的影响显着增加；它们可能会减弱反射并增强发射。获得不同油种和油乳状液的关键辐射参数将有助于推动海面浮油定量光学遥感的实际应用。