Abstract

This study is dedicated to determining the values of the physical parameters of cloud particles in the deep layers of Saturn’s atmosphere using the data from remote measurements of the solar radiation field diffusely reflected by the giant planet. In the previous studies, using the effective optical depth method, from the spectral measurements of the geometric albedo of Saturn in 1993 in the wavelength range of 300–1000 nm, a pressure dependence of the aerosol scattering component of the optical depth, i.e., a change in its value with altitude in the atmosphere, was obtained. The analysis of the initial data was performed in the long-wave part of the spectrum in the methane absorption lines of different levels of absorption with the centers at wavelengths of λ = 619, 727, 842, 864, and 887 nm. At certain altitude levels in the deep layers of the atmosphere of the giant planet, the indicated dependence shows the features that possibly reflect changes in the physical characteristics of aerosol. Therefore, the aim of this work was to determine the possible values of the physical parameters of aerosol particles in the deep layers of Saturn’s atmosphere at altitudinal levels with the features noted above. As a result, an increase in the effective radius of cloud particles was observed in the transition from the outer to the deeper layers of the atmosphere: from 1.4 μm in the upper part of atmosphere to 1.83 μm in the altitudinal region with a pressure of 1.0–1.25 bar and up to 2.2–2.4 μm in the region with a pressure of 1.5–2.0 bar. In the latter segment, a decrease by 3.5% was revealed in the real part of the refractive index of aerosol particles. A possible reason for this decrease is the change in the phase state of aerosol particles in the lower and warmer atmospheric layers of Saturn due to the presence of ammonium hydroxide in their composition at a sufficient high concentration.

中文翻译：

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土星大气深层气溶胶物理特性的可能变化

摘要

这项研究致力于使用来自巨型行星漫反射的太阳辐射场的远程测量数据，确定土星大气深层中云粒子物理参数的值。在以前的研究中，使用有效的光学深度方法，根据1993年土星的几何反照率在300–1000 nm波长范围内的光谱测量结果，气溶胶散射分量对光学深度的压力依赖性，即获得了其值随大气高度的变化。初始数据的分析是在不同吸收水平的甲烷吸收谱线的长波部分中进行的，中心的波长为λ= 619、727、842、864和887 nm。在巨型行星大气深层的某些高度上，指示的依存关系显示出可能反映气溶胶物理特征变化的特征。因此，这项工作的目的是确定土星大气深层中具有上述特征的气溶胶颗粒物理参数的可能值。结果，在从大气的外层到深层的过渡过程中观察到了云颗粒的有效半径的增加：从大气上部的1.4μm到垂直区域的气压为1.0的海拔区域的1.83μm –1.25 bar，在压力为1.5–2.0 bar的区域内最大为2.2–2.4μm。在后一部分中，减少了3。在气溶胶颗粒的折射率的实部中显示出5％。这种降低的可能原因是由于土星的较低大气层和较热大气层中气溶胶颗粒的相态变化，这是由于其成分中存在足够高浓度的氢氧化铵。