The Mars Reconnaissance Orbiter's Shallow Radar (SHARAD) emits radar signals and records their reflections from layer boundaries within the Martian north polar ice cap. Previous studies have suggested that the ice cap is composed of thin dust-rich layers between thicker layers of nearly pure water ice. The prevailing hypotheses suggest that each dust-rich layer represents either a period of ice sublimation at the poles or a period of reduced ice deposition relative to dust deposition. To test whether thin dust beds are a plausible hypothesis for the observed SHARAD reflectors, we use RadSPy (radar sounding simulator in Python, https://github.com/scourvil/RadSPy.git), an open-source N-layer radar sounder forward-modeling software that we have developed and describe herein. We forward model radar data from thin dust-rich beds interspersing pure ice, and compare them to observed radar reflection data over Gemina Lingula in the north polar layered deposits (NPLD). We consider two end-member cases: (1) thin beds composed entirely of dust, but with thickness varying from 0.05 m to 0.4 m; and (2) dust beds all with the same thickness, but with varying dust content. We find that the observed reflections can be explained by either scenario, i.e., varying thickness or varying dust content, and we conclude that a combination of both is likely. More importantly, our results provide lower bounds on the layer thickness and dust fraction for the flat-lying reflectors of Gemina Lingula in the NPLD. Our findings support the thin dust layer hypothesis, providing new constraints on layer composition and geometry for Mars climate researchers.

火星侦察轨道器的浅雷达（SHARAD）发射雷达信号，并记录来自火星北极极冰盖内层边界的反射。先前的研究表明，冰盖是由较厚的近纯水冰层之间的富尘薄层组成。普遍的假设表明，每个富含尘埃的层要么代表两极的冰升华阶段，要么代表相对于尘埃沉积而言减少的冰沉积时期。为了测试薄尘层是否是观察到的SHARAD反射器的合理假设，我们使用了RadSPy（Python中的雷达探测模拟器，https：//github.com/scourvil/RadSPy.git），这是一个开源N我们在本文中开发和描述的多层雷达测深仪正向建模软件。我们从散布有纯冰的薄粉尘丰富的层中转发模型雷达数据，并将其与北极分层沉积物（NPLD）中Gemina Lingula上观测到的雷达反射数据进行比较。我们考虑了两种末端构件情况：（1）薄床完全由灰尘组成，但厚度在0.05 m至0.4 m之间变化；（2）灰尘床的厚度均相同，但灰尘含量却有所不同。我们发现，观察到的反射可以用两种情况来解释，即厚度变化或粉尘含量变化，并且我们得出结论，两者可能结合在一起。更重要的是，我们的结果为NPLD中Gemina Lingula平躺反射镜的层厚度和粉尘分数提供了下限。