The radiative transfer theory with packed media correction (RTT-PM) is a balanced, physically rigorous, and practical light scattering model that is suitable for modeling reflectance and similar spectra of densely packed particulate media. The static structure factor correction to the classical radiative transfer solution and actualization of fundamental particles of media with spheres or aggregates are key properties of this model that ensure both physical rigor and practical efficiency. We improved upon the assumptions in the RTT-PM method by incorporating irregularly shaped Gaussian particles into its scheme. This incorporation of Gaussian particles is a notable advancement for applications of the RTT-PM method to planetary surfaces that often are layers of irregularly shaped particles. With the Gaussian particle RTT-PM method, we modeled spectra of Saturnian moons Dione, Rhea, and Tethys observed with the Cassini Visual and Infrared Mapping Spectrometer (VIMS), assuming pure water ice composition. For Rhea and Tethys, the Gaussian particle RTT-PM technique modeled VIMS spectra better than models with spherical or aggregate particles, strengthening prior suggestion that particles on Rhea and Tethys are solid, non-spherical particles. Dione's spectra were best modeled not with Gaussian particles but rather with an aggregate of 128 monomers. This makes Dione's icy regolith different from that on Rhea and Tethys. Prior studies have indicated that the cause for the difference might arise from the presence of surface macrostructures or absorbing materials on Dione, but according to our modeling results, increased multiple scattering from small fluffy aggregate particles is an alternative explanation.

具有填充介质校正的辐射传输理论 (RTT-PM) 是一种平衡的、物理上严谨的、实用的光散射模型，适用于模拟密集颗粒介质的反射率和类似光谱。经典辐射传输解决方案的静态结构因子校正和具有球体或聚集体的介质基本粒子的实现是该模型的关键属性，可确保物理严谨性和实际效率。我们通过将不规则形状的高斯粒子合并到其方案中来改进 RTT-PM 方法中的假设。高斯粒子的这种结合是 RTT-PM 方法应用于行星表面的显着进步，行星表面通常是不规则形状的粒子层。使用高斯粒子 RTT-PM 方法，卡西尼视觉和红外测绘光谱仪（VIMS），假设纯水冰成分。对于 Rhea 和 Tethys，高斯粒子 RTT-PM 技术比球形或聚集粒子模型更好地模拟 VIMS 光谱，加强了先前的建议，即 Rhea 和 Tethys 上的粒子是固体、非球形粒子。Dione 的光谱最好不是用高斯粒子建模，而是用 128 个单体的聚合体建模。这使得 Dione 的冰冷风化层与 Rhea 和 Tethys 上的不同。先前的研究表明，造成这种差异的原因可能是由于 Dione 上存在表面宏观结构或吸收材料，但根据我们的建模结果，来自小的蓬松聚集体颗粒的多重散射增加是另一种解释。