Detection of water-ice deposits using synthetic aperture radar (SAR) is a cost-effective, and efficient approach to understand lunar water resources. As water is crucial to supporting human-based space exploration, current and near upcoming lunar missions are primary concentrated on mapping and quantification of water ice exposures on surface and subsurface levels. The circular polarization ratio greater than one (CPR >1) derived using the orbital radar observations is considered as an important SAR derived parameter for water-ice detection. This study aims to investigate 14 craters near the lunar poles with high CPR (CPR >1), as identified in previous studies, using the L-band (24 cm) dual frequency synthetic aperture radar (DFSAR) onboard Chandrayaan-2. In addition to CPR, we computed the degree of polarization (DOP) after applying parallax error correction that helps in reducing misinterpretation. Our findings are based on orthorectified DFSAR calibrated data analysis. We found that the CPR of crater interiors is not significantly different from that of their surroundings, and this pattern is consistent throughout all the 14 craters selected. Further, we also found a linear inverse relationship between CPR and DOP for the interior and exteriors of the craters, with R-2 0.99, indicating a strong correlation between these two parameters. We found only 2 % of total pixels are above CPR > 1, which indicates that there is less possibility of homogeneous water-ice but the possibility of water-ice mixed with the subsurface regolith cannot be ruled out.

The effect of topography on the amplification of seismic forces has been considered in regulations, and they have deemed the use of the seismic force amplification coefficient in the design of adjacent earth-retaining structures necessary. However, the impact of settlement-reducing or anti-sliding piles under the building foundation on the applied acceleration to the foundation is generally not addressed in regulations, and it is necessary to carefully examine this issue for the optimal design. This study sought to empirically assess the impact of using piles as Combined Piled Raft Foundation (CPRF) positioned on the top of slopes, with different slope angles, on the seismic behavior of slopes, scaled at 1/25th, through shaking table experiments. Six sinusoidal waves were created as input motions to simulate a range of earthquake scenarios, applied to the models to collect data for analyzing the seismic response of the system. No.161 Firouzkooh sand was utilized as the soil in this investigation. The amplification factor (AF) of various locations was used to examine the seismic response of the system. The findings underscore the importance of the amplification factor as a critical parameter in evaluating the seismic response of foundations situated on slope crests. Additionally, Implementing CPRF and longer piles had a mitigating effect on accelerations at most points and improved the seismic response of the slopes, reducing amplification factor and led to less damages. Furthermore, the slope angle was shown to significantly influence the seismic response, with steeper angles generally resulting in higher amplifications at the slope crest.

The Black carbon (BC) and Brown carbon (BrC) concentration has been measured over Srinagar (Garhwal) in central Himalayas during October 2020 to September 2021 periods. The average BC mass was 2.59 +/- 1.96 mu g m- 3 and its absorption coefficients were abundant at shorter wavelength. BC seasonal variation exhibited a significant variability, with highest during winter (4.54 +/- 2.64 mu g m- 3) followed by pre-monsoon (2.69 +/- 2.04 mu g m- 3) and post-monsoon (1.93 +/- 0.91 mu g m- 3) while lowest was observed in the monsoon (1.05 +/- 0.54 mu g m- 3). Relatively high contribution of total spectral light absorption coefficient (Abs lambda) was observed (75.94 Mm-1) at 370 nm than longer wavelength (16.86 Mm-1) at 950 nm. The BrC contribution was higher at 370 nm (32.50 Mm-1) to the total babs (lambda), while at higher wavelengths it has extensively decreased (2.54 Mm-1 at 660 nm). Seasonally, the absorption coefficient of BC and BrC was greater in winter (83.99 and 68.37 Mm-1) while lowest in monsoon (19.38 and 9.27 Mm-1), respectively. The babs BrC/babs (t) ratio revealed higher contribution of BrC in winters. The secondary brown carbon (BrCsec) and primary brown carbon (BrCpri) contributed 43.16 % and 56.88 % towards the total BrC Abs (lambda) at 370 nm with higher in winter and lowest in monsoon, respectively. BrCsec and BrCprim has shown higher contribution in evening (18.00-20.00 h) and in morning (09.00-11.00 h) hours. The average radiative forcing (RF) of BC was 36.11 +/- 6.99 Wm-2, 2.19 +/- 1.22 Wm-2 and -33.92 +/- 5.96 Wm-2 at the atmosphere (ATM), Top of the Atmosphere (TOA), and at the Surface (SUR), respectively.

Understanding the reachability of water ice by future in-situ experiments near the lunar poles is crucial for supporting growing exploration plans and constraining the uncertainties on its genesis and distribution. To achieve this objective, we perform a thorough three-dimensional mapping of the distribution of water ice in the lunar polar regions (70 degrees onward), integrating radar, optical, and neutron detector observations from the Lunar Reconnaissance Orbiter mission (LRO). Our analysis reveals similar to 5-to-8-fold larger expanse of subsurface water ice (similar to 1-3 m depth) compared to surface water ice (up to 1 m depth) for the north and south poles, respectively. Our investigation cannot rule out the possibility of deep-seated water ice deposits in the lunar poles that remains beyond the detection capabilities of existing instruments on LRO. Moreover, we find that the extent of water ice in the northern polar region (similar to 1100 +/- 74 km(2)) is twice that in the southern polar region (similar to 562 +/- 54 km(2)). Our mapping also suggests that the dichotomous latitudinal distribution and the antipodal longitudinal distribution of water ice are likely driven by Mare volcanism and preferential cratering. We provide additional evidence that outgassing during Imbrian volcanism was probably the primary source of subsurface water ice in the lunar poles, which favors larger expanse over meteoritic sources.

Circular Polarization Ratio (CPR) and bistatic angle (beta), obtained using Arecibo Observatory Planetary Radar, are the two important parameters for determining the presence of water-ice on the lunar surface. In this paper investigation on the possibility of water-ice deposits on the Erlanger crater floor, located in the Permanently Shadowed Regions (PSRs) of the lunar surface has been done using bistatic Mini-RF synthetic aperture radar (SAR) data. In order to better characterize the Erlanger crater, topographic, morphology map, temperature map, PSR map, Lunar Reconnaissance Orbiter Wide Angle Camera (WAC) image, circular polarization ratio (CPR), m-chi decomposition method and bistatic angle (beta) were utilized. We have found that the Erlanger crater and its surroundings comply with the CPR > 1 condition Spudis et al. (Geophysical Research Letter 37, 2010). In the crater floor, it was also observed that parameter beta was very high, which is not a favorable condition for the water-ice regions possible. Furthermore, observations have been obtained using the m-chi decomposition method. Based on a comprehensive analysis from the SAR parameter and m-chi decomposition, the Erlanger crater exhibits characteristics of non-icy regions. Additionally, topography, morphology, temperature, and hydrogen map-based information have been observed. The comprehensive analysis suggested that the Erlanger is a young and fresh crater. From the pixels-based analysis it has been found that the availability of the possible water-ice deposits within the crater rim is very less.

High circular polarization ratio (CPR) characteristics were found in permanently shaded regions (PSRs) near the lunar poles. High CPR was regarded as a water ice index. The compact-polarimetric (CP) miniature radio frequency (Mini-RF) radar transmits left-circularly polarized signals and receives horizontally polarized ($S_{\text {HL}}$ ) and vertically-polarized ($S_{\text {VL}}$ ) echoes from the lunar surface. Statistics of the CPR data show its relations with the relative phase ($\delta$ ) between $S_{\text {HL}} $ and $S_{\text {VL}} $ and the degree of polarization ($m$ ) but few interpretations were provided. The average CPR data reach the maximum and minimum at $\delta =\pm 90{\circ }$ , respectively. As $m$ becomes very small, the CPR approaches 1. It has been found that CPR is also affected by surface roughness and incidence angle of radar waves. The CPR is now expressed in CP mode to explain the Mini-RF observation. Full-polarimetric radar echoes and CP parameters of the lunar surface are numerically simulated using the bidirectional analytic ray-tracing method. Single-bounce and multiple-bounce scattering components are included in the simulation. Radar images of the lunar crater are simulated with the digital elevation model (DEM) data. The $H-\alpha $ decomposition derived from the full-polarimetric simulation is presented to analyze $\delta $ and $m$ . Simulated radar images with different surface roughness are analyzed statistically to study the functional dependences of $\delta $ , ${m}$ , and CPR on incidence angle and roughness. Relationships among $\delta $ , $m$ , and CPR are used to analyze the effects of incidence angle, roughness, TiO2, and rock abundance on the scattering components. The CPR, $m$ , and $\delta $ of PSR craters of different ages are compared with those of nonpolar craters. The results indicate that the CPR, $m$ , and $\delta $ are unlikely to be unambiguous evidence of water ice.

Black carbon (BC), primary brown carbon (BrCpri), and secondary brown carbon (BrCsec) are important light-absorbing aerosol. BC and BrC from the surrounding area can reach the Tibetan Plateau (TP) and influence climate change and glacial melting. Here, we presented a study of the light absorption, radiative forcing, and potential source areas of BC and BrC over the northeastern, central, and southwestern TP. The higher light absorption was observed in the northeastern and southwestern sites compared to the central TP site. The major carbonaceous light-absorbing was attributed to BC with the percentages of 65%, 56%, and 82% in Ngari, Qinghai Lake, and Beiluhe, respectively. The heighten contribution of BrCsec to total light absorption indicated the importance of BrCsec in the TP, especially in the northeastern and southwestern areas. The BrCsec radiative forcings relative to BC were much higher than those of BrCpri. The potential BC and BrCpri source distributions were obtained.

Radar measured elevated circular polarization ratio (CPR) from lunar polar region are not unique signature of lunar water ice deposits, It may also be caused by wavelength scale roughness e.g. fragments from fresh ejecta which forms corner reflectors. Thus, there is a need to assess the role of other remotely sensed parameters along with elevated CPR for water ice detection. The study derives the morphological parameters like crater diameter (D), crater depth (d), crater floor diameter, d/D ratio along with annual temperature, surface roughness and backscattering coefficient (S1). Association of these parameters for fresh craters and craters with water ice was studied. The results indicate that morphological parameters such as surface slope, surface roughness and d/D ratio influences crater which exhibits high CPR only in their interiors (anomalous). Furthermore, analyzing d/D ratio and surface roughness with CPR shows unambiguous separation between them. These observations emphasizes role of morphometry in detecting craters having water ice.

Circular polarization ratio (CPR) was regarded as an important index for water ice existence in permanently shadowed region (PSR) of the Moon poles. However, some studies have intuitively described that the double bounce scattering caused by dihedral structure of stone facets may yield high CPR as well. In this paper, a numerical model of the Moon cratered rough surface with volumetric scatterers, e.g. rock-stones, is developed. The bidirectional analytic ray tracing (BART) method is applied to numerically solve high-order scattering of lunar rough surface and volumetric rock-stones. The lunar surface is modeled by Digital Elevation Model (DEM) data from Lunar Reconnaissance Orbiter (LRO) Lunar Orbiter Laser Altimeter (LOLA). It is the first numerical approach to quantitatively analyze how the cratered surface topography, discrete stones and radar local incidence etc. affect and enhance the CPR.

There have been several investigation about water-ice depositions on the lunar polar regions. Earlier, studies were based on criterion circular polarization ratio (CPR). However, It is quite challenging to classify waterice deposits on the basis of criterion CPR>1, because it occurs in water-ice and rough surface region both. Thus, it is essential to examine the CPR>1, laterally with other significant parameters fractal dimension and conformity coefficient (mu) for better classification. First fractal dimension (D) based method has been used to differentiate between the rough and smooth surface. Further, conformity coefficient (mu) is used to identify possible water-ice region associated with volume scattering. This dominant volume scattering pixels points were extracted from the degree of polarization (DOP) for better classification. Finally, obtained results have been compared with existing methods. The entire study indicates that the classification of water-ice deposits using conformity coefficient (mu) gives good results.