To evaluate the availability of the volcanism study, the microwave sounder (Chinese lunar exploration project, a microwave sounder, CELMS) data from Change'E -2 satellite were employed in this study to compare with the geologic results derived from optical data and radar data of Mare Imbrium, which is presented as the long duration and the last extensive phase of lunar volcanism. First, the normalized brightness temperature (T _B ) is generated to eliminate its strong latitude-dependent effect, which implies a good correlation with the titanium abundance. Moreover, difference between T _B of the same frequency at noon and that at midnight (dT _B ) is deduced to evaluate the absorption features of the lunar regolith. According to the dT _B change with frequency, a new geologic perspective is given to Mare Imbrium. The new interpretation map largely agrees with optical results in the regions with high (FeO + TiO2) abundance (FTA), and with the interpretation maps by radar data in the regions with low FTA. The statistical results validate the three-phase volcanism in Mare Imbrium. This study also hints the special importance of the CELMS data in understanding the basaltic volcanism of the Moon.

Compared to various optical remote sensing data, studies on the performance of dual-pol Synthetic aperture radar (SAR) on lithology discrimination are scarce. This study aimed at using Sentinel-1 data to distinguish dolomite, andesite, limestone, sandstone, and granite rock types. The backscatter coefficients VV and VH, the ratio VV–VH; the decomposition parameters Entropy, Anisotropy, and Alpha were firstly derived and the Kruskal–Wallis rank sum test was then applied to these polarimetric derived matrices to assess the significance of statistical differences among different rocks. Further, the corresponding gray-level co-occurrence matrices (GLCM) features were calculated. To reduce the redundancy and data dimension, the principal component analysis (PCA) was carried out on the GLCM features. Due to the limited rock samples, before the lithology discrimination, the input variables were selected. Several classifiers were then used for lithology discrimination. The discrimination models were evaluated by overall accuracy, confusion matrices, and the area under the curve-receiver operating characteristics (AUC-ROC). Results show that (1) the statistical differences of the polarimetric derived matrices (backscatter coefficients, ratio, and decomposition parameters) among different rocks was insignificant; (2) texture information derived from Sentinel-1 had great potential for lithology discrimination; (3) partial least square discrimination analysis (PLSDA) had the highest overall accuracy (0.444) among the classification models; (4) though the overall accuracy is unsatisfactory, according to the AUC-ROC and confusion matrices, the predictive ability of PLSDA model for limestone is high with an AUC value of 0.8017, followed by dolomite with an AUC value of 0.7204. From the results, we suggest that the dual-pol Sentinel-1 data are able to correctly distinguish specific rocks and has the potential to capture the variation of different rocks.

As the capital city of China, Beijing has experienced unprecedented economic and population growth and dramatic impervious surface changes during the last few decades. An application of the classification method combining the spectral and textural features based on Random Forest was conducted to monitor the spatial and temporal changes of Beijing’s impervious surfaces. This classification strategy achieved excellent performance in the impervious surface extraction in complex urban areas, as the Kappa coefficient reached 0.850. Based on this strategy, the impervious surfaces inside Beijing’s sixth ring road in 1997, 2002, 2007, 2013, and 2017 were extracted. As the development of Beijing has a special regional feature, the changes of impervious surfaces within the sixth ring road were assessed. The findings are as follows: (1) the textural features can significantly improve the classification accuracy of land cover in urban areas, especially for the impervious surface with high albedo. (2) Impervious surfaces within the sixth ring road expanded dramatically from 1997 to 2017, had three expanding periods: 1997–2002, 2002–2007, and 2013–2017, and only shrank in 2007–2013. There are different possible major driving factors for each period. (3) The region between the fifth and sixth ring roads in Beijing underwent the most significant changes in the two decades. (4) The inner three regions are relatively highly urbanized areas compared to the outer two regions. Urbanization processes in the interior regions tend to be completed compared to the exterior regions.

The Chang’e-1/2 satellites carried microwave radiometers (MRM), which supplied unique passive microwave data, supplementing visible, thermal infrared, and radar data in current lunar studies. However, the application of MRM data is constrained by the limited amount of the original dataset, which cannot express spatial variations at given local times. In this study, we present a novel approach to constructing a local-time brightness temperature (TB) model using barycentric interpolation based on Delaunay tetrahedralization. This model enables the generation of a complete TB dataset, producing TB maps that are both continuous and self-consistent in both spatial and temporal domains. Compared to the traditional methods, those generated in this work avoid a ~7-K bias on a global scale. Furthermore, the interpolated maps offer superior representations of the TB over time for various lunar surfaces. The preliminary evaluations on global and regional scales hint important application of MRM data in studying the geological features of the Moon.

Mare Moscoviense (148°E, 27°N) is one of the few large maria on the lunar farside, with the thinnest crust and a positive gravity anomaly. In this paper, the Chang’E-2 Microwave Sounder (CELMS) data was employed to study the microwave thermal emission features of mare basalts in Moscoviense Basin. The time angle and linear interpolation method are used to generate the brightness temperature (T_B) maps at noon and night, as well as the T_B difference (dT_B) map. The obtained important results are as follows. (1) A new geologic map is generated with the T_B and dT_B maps using the maximum likelihood method, which gives a new expression about the basaltic units in Mare Moscoviense compared to the optical results; (2) the substrate temperature of Moscoviense Basin is likely warmer than what we know; (3) unit Ihtm (a Late (?) Imbrian, mid- to high-Ti, high-Fe basalt) is re-understood as two independent volcanic features with their own fissures; (4) the dT_B maps firstly indicate that the depth lunar regolith is homogeneous in the highlands surrounding Mare Moscoviense, at least in the microwave domain, and secondly that there exists a special material bringing about the low dT_B anomaly in the shallow layer of the east highlands. The results will be of great significance to better understand the basaltic volcanism of the Moon.

The influence of rocks on the microwave thermal emission (MTE) of the lunar regolith has not been fully studied with the four-channel microwave radiometer (MRM) data onboard Chang’e-1/2 satellites. To highlight the influence of the rocks on the MTE of the regolith, the Hertzsprung basin located near the lunar equator in highland regions is selected as the study area. The comparison between the brightness temperature (TB) maps derived from the Chang’e-2 MRM data and rock abundance (RA) map derived from the Diviner data postulates three special issues about the correlation between the MTE features and the regolith with rocks. Then, aimed to interpret the issues, two new layered regolith models and the corresponding radiative transfer models are constructed. The main results are as follows. First, the observation and the simulation both verify that the regolith with rocks will provide a cold TB anomaly at night and at low frequencies at daytime, but result in a hot anomaly at high-frequency at daytime. Moreover, the temperature profiles of the regolith with surface and hidden rocks are evaluated with the theoretical model. Second, the simulation results verify the existence of the hidden rocks in the lunar regolith assumed when studying the TB performances of the Hertzsprung basin. Third, the rock distribution revealed by the TB maps shows a different view compared to that estimated by the Diviner data in space and values, and the change of the TB with frequencies postulates a new view about the variation of the RA with depth. This study hints that the MRM data probably provide a new way to quantitatively estimate the RA values of the lunar regolith, and the results will be meaningful to improve understanding of the evolution of the impact craters.