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A Moon-based Earth observation multispectral camera provides a unique perspective for observing large-scale Earth phenomena. This study focuses on the analysis of the field of view (FOV) for such a sensor. Unlike space-borne sensors, the analysis of the FOV for a Moon-based sensor takes into account not only Earth's maximum apparent diameter as seen from the lunar surface but also the Earth's and the solar trajectory in the lunar sky, as well as the pointing accuracy and pointing adjustment temporal intervals of the turntable. Three critical issues are analyzed: (1) The relationship between the Earth's apparent diameter and the Earth's phase angle is revealed. It is found that the Earth's maximum apparent diameter encompasses the Earth's full phase, suggesting the FOV should exceed this maximum. (2) Regardless of the location on the lunar surface, a sensor will suffer from solar intrusion every orbital period. Although the Earth's trajectory forms an envelope during an 18.6-year cycle, the FOV should not be excessively large. (3) To design a reasonable FOV, it is necessary to consider both the pointing accuracy and pointing adjustment temporal interval comprehensively. All these insights will guide future Moon-based Earth observation multispectral camera design. [ABSTRACT FROM AUTHOR]

Ocean observational gridded products are vital for climate monitoring, ocean and climate research, model evaluation, and supporting climate mitigation and adaptation measures. This paper describes the 4th version of the Institute of Atmospheric Physics (IAPv4) ocean temperature and ocean heat content (OHC) objective analysis product. It accounts for recent developments in quality control (QC) procedures, climatology, bias correction, vertical and horizontal interpolation, and mapping and is available for the upper 6000 m (119 levels) since 1940 (more reliable after ∼ 1957) for monthly and 1°×1° temporal and spatial resolutions. IAPv4 is compared with the previous version, IAPv3, and with the other data products, sea surface temperatures (SSTs), and satellite observations. It has a slightly stronger long-term upper 2000 m OHC increase than IAPv3 for 1955–2023, mainly because of newly developed bias corrections. The IAPv4 0–2000 m OHC trend is also higher during 2005–2023 than IAPv3, mainly because of the QC process update. The uppermost level of IAPv4 is consistent with independent SST datasets. The month-to-month OHC variability for IAPv4 is desirably less than IAPv3 and the other OHC products investigated in this study, the trend of ocean warming rate (i.e., warming acceleration) is more consistent with the net energy imbalance at the top of the atmosphere than IAPv3, and the sea level budget can be closed within uncertainty. The gridded product is freely accessible at 10.12157/IOCAS.20240117.002 for temperature data (Cheng et al., 2024a) and at 10.12157/IOCAS.20240117.001 for ocean heat content data (Cheng et al., 2024b). [ABSTRACT FROM AUTHOR]

The burgeoning field of semiconductor‐mediated organic conversion is of paramount significance, with zinc indium sulfide (ZnIn2S4) emerging as a standout candidate owing to its benign nature, optimal bandgap, extensive light absorption spectrum, remarkable physicochemical properties, and straightforward synthesis. This review examines the latest breakthroughs and the trajectory of ZnIn2S4‐based photocatalysts in the realm of selective organic transformation. We start with a distinct overview of the intrinsic physical attributes of ZnIn2S4 and the underlying mechanisms driving its efficacy in photocatalytic organic transformations. Subsequently, the preparation methods of ZnIn2S4 are summarized. The main focus is the state‐of‐the‐art photocatalytic application of various ZnIn2S4‐based photocatalysts, such as redox reactions, the construction of C−C, C−S and S−S bonds, and the cleavage of C−O, C−C, and C=C bonds. In the conclusion part, we provide our perspectives on the prospective advancements and the remaining challenges that lie ahead in the optimization of ZnIn2S4‐based photocatalysts, with the ultimate goal of enhancing their efficacy for a diverse array of photosynthetic applications. It is anticipated to inspire the strategic engineering of ZnIn2S4 and other semiconductor‐based photocatalysts for various artificial photosynthesis reactions. [ABSTRACT FROM AUTHOR]

As a natural satellite of the Earth, the moon is a prime target for planetary remote sensing exploration. However, lunar polarization studies are not popular in the planetary science community. Polarimetry of the lunar surface had not been carried out from a spacecraft until the Korean lunar exploration program was initiated. In previous polarization observations of the moon, images of different polarization states were obtained by a rotating linear polarizer. This method is not well suited for future polarization observations from space-based spacecraft. To this end, we present a new kind of polarized observation of the moon using a division of a focal-plane polarization camera and propose a pipeline on the processing method of the polarization observation of the moon. We obtain a map of the degree of white-light polarization on the nearside of the moon through polarization observation, data processing, and correction. The observation and data processing methods presented in this study have the potential to serve as a reference for analyzing polarization observation data from future orbiting spacecraft. These are expected to lead to new discoveries in the fields of astronomy and planetary science. [ABSTRACT FROM AUTHOR]

A Moon‐based sensor can observe the Earth as a single point and achieve disk‐integrated measurements of outgoing longwave radiation (OLR), which significantly differs from low orbital, geostationary, and Sun–Earth L1 point platforms. In this study, a scheme of determining the disk‐integrated Earth's OLR based on a Moon‐based platform is proposed. The observational solid angle was theoretically derived based on the Earth's ellipsoid model and the disk‐integrated observational anisotropic factor was estimated to eliminate the effects of the Earth's radiant anisotropy. The simulated disk‐integrated Earth's OLR obtained from a Moon‐based platform varies periodically, due to changes in the observation geometry and Earth's scene distribution within the observed Earth's disk. Clouds, meteorological parameters, and the land cover distribution notably affect the disk‐integrated Earth's OLR. By analyzing the disk‐integrated Earth's OLR from a Moon‐based platform, significant variabilities were investigated. Additionally, the Earth's shape and radiant anisotropy that affecting the disk‐integrated Earth's OLR were estimated. In conclusion, a more realistic Earth's shape, the latest version of the angular distribution model (ADM), and accurate land cover and meteorological datasets are needed when determining the disk‐integrated Earth's OLR. It is expected the unique variability captured by this platform and its ability to complement traditional satellite data make it a valuable tool for studying Earth's radiation budget and energy cycle, and contributing to diagnostic of the climate General Circulation Models (GCM) performance. Plain Language Summary: Observing large‐scale geoscience phenomena poses a significant challenge, necessitating observations that guarantee spatial continuity and temporal consistency. Equipping sensors on the lunar surface can observe the whole Earth's disk, which is a feasible way to complement the existing satellites. Determining the disk‐integrated Earth's OLR from a Moon‐based platform helps in exploring its potential for detecting geoscience phenomena at different scales. Our study finds that the Moon‐based disk‐integrated Earth's OLR would provide full coverage of the whole Earth's phase angle during one sidereal month. The day‐night and land‐ocean effects on the Moon‐based disk‐integrated OLR during one sidereal month would provide substantial variability to compare to similarly sampled GCM output comparison that is not available from conventional satellite data. Such these unique variabilities in the Moon‐based disk‐integrated Earth's OLR make the Moon a valuable Earth observation platform for studying Earth's radiation budget and energy cycle, and evaluating the performance of GCMs. Key Points: Disk‐integrated Earth's outgoing longwave radiation are estimated considering Earth's shape and radiant anisotropyOverall understanding of the variability on Moon‐based disk‐integrated Earth's outgoing longwave radiationDiscussing the characteristics of Moon‐based disk‐integrated Earth's outgoing longwave radiation [ABSTRACT FROM AUTHOR]

H2V3O8/GaN n–n heterojunction ultraviolet photodetectors are fabricated via a facile dip-coating method. The Schottky junction between the GaN and H2V3O8 builds a built-in electric field to achieve the self-powered phenomenon. The photodetector presents a high photocurrent (0.23 μA) and a fast response speed (less than 0.3 s) at 0 V bias and under 365 nm light illumination (24.50 mW cm−2). Furthermore, the photocurrent increases steadily as the light intensity increases from 0.53 to 24.50 mW cm−2. The H2V3O8/GaN heterojunction holds great potential to realize high-performance hybrid PDs. [ABSTRACT FROM AUTHOR]

Observation angles are of great importance with respect to Earth observation platforms. The richness of angular combination, i.e., the combination of three observational angles (viewing zenith angle, solar zenith angle, and relative azimuth angle), is an important parameter to illustrate the angle sampling capability of an Earth observation platform. Here, the angular combination characteristics of a Moon-based platform were investigated and compared with existing artificial satellites. Furthermore, the effects of the time sampling interval on the angular combination characteristics were analyzed using a newly established angular combination number index (ACNI). Results show that a Moon-based platform can complement angular sampling observations from existing satellites. We found that the time sampling interval has different effects on the angular combination for different observed points. Accordingly, the Earth's surface can be divided into two zones with respect to its sensitivity to the time sampling interval. When the time sampling interval increased from 10 min to 2 h, the maximum loss of the angular combination reached 50% for the observed points in the mid–low latitude zone. [ABSTRACT FROM AUTHOR]

Alnustone, a diarylheptane compound, exhibits potent growth inhibition against hepatocellular carcinoma (HCC) BEL‐7402 cells. However, the underlying mechanisms associated with its anticancer activity remain unknown. In the present study, we evaluated the anticancer effect of alnustone against several human cancers focused on HCC and the possible associated mechanisms. The results showed that alnustone significantly inhibited the growth of several cancer cells by CCK‐8 assay. Alnustone markedly induced apoptosis and decreased mitochondrial membrane potential in BEL‐7402 and HepG2 cells. Alnustone inhibited the expression of proteins related to apoptosis and PI3K/Akt/mTOR/p70S6K pathways and generated ROS production in BEL‐7402 and HepG2 cells. Moreover, N‐acetyl‐L‐cysteine (NAC, a ROS inhibitor) could significantly reverse the effects of alnustone on the growth inhibition of BEL‐7402 and HepG2 cells and the expression of proteins related to apoptosis and PI3K/Akt/mTOR signaling pathway in HepG2 cells. Furthermore, alnustone significantly inhibited tumor growth of HepG2 xenografts, obviously induced apoptosis in the tumor tissues and improved the pathological condition of liver tissues of mice in vivo. The study provides evidence that alnustone is effective against HCC via ROS‐mediated PI3K/Akt/mTOR/p70S6K pathway and the compound has the potential to be developed as a novel anticancer agent for the treatment of HCC clinically. [ABSTRACT FROM AUTHOR]

A Moon-based platform can provide efficient observations of large-scale geoscience phenomena on Earth. This study focuses on the global spatio-temporal sampling characteristics of Moon-based Earth observations and quantifies the variations of the spatio-temporal sampling distributions to establish a suitable accumulated sampling period. A theoretical derivation is performed based on the parametric equations, while proposing a metric for measuring the uniformity of the spatio-temporal distributions. Results show that the distributions are mainly affected by the position of the nadir corresponding to the start time and the accumulated sampling period. We find that the accumulated spatio-temporal sampling presents a strong periodicity with one orbital period. [ABSTRACT FROM AUTHOR]

Due to the almost hemispheric observational scope of the Moon-based Earth observations, the effects of sampling time interval on the image offsets of the observed points are fundamentally different from the cases of traditional satellite-based platforms. Sampling time intervals will affect the offsets in the full-disc image, while the magnitude of the image offsets is dependent on the spatial resolution. Hence, their relationships merit further investigation. To this end, a novel method to determine the image coordinates based on radius-angle pair expression is proposed. The offsets of the observed points between two adjacent samplings can be calculated and the effects of the sampling time interval on the offsets can be analysed. We found that the magnitude of the image offsets in the x-axis direction is approximately two times larger than that in y-axis direction under the same sampling time interval and the effects of the sampling time interval is related to the observed point's latitude. Further, based on the fact that the maximum offsets occur at the Earth's equator, the detailed calculation of the shortest sampling time interval taken to exceed 1-pixel offset corresponding to different spatial resolutions is carried out. The results described herein can provide guidance for designing sensors for Moon-based Earth observations. [ABSTRACT FROM AUTHOR]

The Moon, Earth's only natural satellite, is a potential new platform for Earth observation. Moreover, with the wide applicability of the angular information from remote sensing data, it has been attracting increasingly more attention. Accordingly, this study focuses on the angular characteristics of Moon-based Earth observations. Using ephemeris DE430 and Earth orientation parameters, the position and attitude of the Sun, Earth, and Moon were obtained and their coordinates normalized to a single framework using coordinate transformations between the related reference systems. Then, an angular geometric model of Moon-based Earth observations was constructed, and the corresponding angular algorithms were presented. The results revealed the angular range and distribution characteristics of Moon-based Earth observations. For every point on the surface of the Earth, the view and solar zenith angles all vary widely, which decreases with increasing latitude. The view and solar zenith angles all vary widely with the largest range of values in the equatorial and polar regions and a smaller range of values in mid-latitudes. Furthermore, the range of solar angles of Moon-based Earth observations is the same as that of all-time solar angles, indicating the potential for monitoring and understanding large-scale geoscientific phenomena using Moon-based Earth observations. [ABSTRACT FROM AUTHOR]

The Moon is a potential new platform for Earth observation. The advantages of its large-scale observational scope, long temporal duration, and multi-layer detecting of the Earth will undoubtedly advance our understanding of the Earth system. To carry out the observations from a Moon-based optical sensor, the geolocation error caused by exterior orientation elements need to be investigated. This paper analyses the error effects of exterior orientation elements on geolocation for an optical sensor. To estimate the error, we present a geometric image model and utilise some parameters to measure the image offsets. Through a large number of numerical simulations, the results demonstrate that the image offsets are not obvious influenced by the distance and observation angle at mid-high latitude of the Moon and have linear correlation with the increasing errors of the exterior orientation elements. Further, the relationship between the spatial resolution and errors of exterior orientation elements are revealed. Finally, the error characteristics for Moon-based Earth observation are discussed. It is expected that the conclusion drawn in this paper could support the study of a Moon-based Earth observation optical sensor. [ABSTRACT FROM AUTHOR]

Moon-based platform is a potential platform that can realize the observations of large-scale geoscience phenomenon. Unlike existing earth observation platforms, the moon-based platform is equipped on a natural celestial body. Its position is calculated by the lunar position and libration derived from the planetary ephemeris. However, limited to the astrometric model and accuracy of observational data, no planetary ephemeris can provide absolutely accurate data, and this will lead to a platform’s position error. This letter investigates the impacts of the platform’s position error on geolocation for a moon-based sensor. We first made comparisons to the lunar position and libration derived from different planetary ephemerides so as to evaluate the magnitude of the platform’s position error. Then, the Monte Carlo method was applied to simulate the platform’s position error. According to the geometric model, the effects of the platform’s position error on geolocation were presented. The results showed the effects of lunar libration error are associated with position on the lunar surface, while the differences of lunar position error effects are not evidently shown in different positions on the lunar surface. Furthermore, high-latitude regions of the moon are demonstrated to have less impact on the platform’s position error, which would be suitable for equipping earth observation sensors. [ABSTRACT FROM AUTHOR]

This study investigates the temporal sampling error on the Earth's outgoing radiation, with a potential Earth observation platform, the Moon-based platform. To simulate the Earth's outgoing radiation viewed from a Moon-based platform, we used the datasets of the NASA's Goddard Earth Observing System Version 5 (GEOS-5) systems as the truth. The analysis is proposed by sampling the simulated time series. The sampling uncertainty associated with a given sampling interval is measured by computing the Root-Mean-Square-Error (RMSE) of the original and subsampled time series. The effects of different sampling intervals are evaluated by maximum bias. The effects of different sampling time are estimated by comparing correlations between the subsampled time series of different start time at specific temporal interval and the origin. The results show that the temporal sampling errors have the characteristics of the periodical uncertainties and bias, and 4-h sampling interval is a turning point. The sampling interval larger than 4 h will result in large uncertainties and bias. [ABSTRACT FROM AUTHOR]

As the earth's only natural satellite, the Moon has unique advantages as an earth observation platform because of its long observation distance and the vast expanse of the lunar surface. To observe the earth from the Moon, the looking vector direction and its variation regularity need to be investigated. In this paper, we first establish a Moon-based earth location algorithm to reveal the variations of the looking vector. In this algorithm, assuming the sensor points to the earth, the looking vector expressed as azimuth and elevation angles is calculated, and the intersection point between the looking vector and the earth's ellipsoid is solved using the relevant equations. The mathematical expression of the observational scope is also derived so as to determine the looking vector range if the looking vector direction is limited in the earth disk. Based on this algorithm, we describe the earth's motion in the lunar topocentric coordinate system and analyze the looking vector direction characteristics by assuming different positions on the lunar surface. In addition, the earth location error is evaluated by adding the looking vector errors. The results show that sensors at different positions on the lunar surface have different looking vector pointing characteristics and different earth location errors. The earth location error is relatively small in the high-latitude region of the Moon. Combining the restriction of lunar local topography, we suggest that the regions that latitude between 30 °N and 80 °N or 30 °S and 80 °S are the ideal locations for the Moon-based earth observation platform. [ABSTRACT FROM AUTHOR]

As a new concept platform for Earth observation, a Moon-based platform has the advantages of large-scale, constant and long-term dynamic Earth observations that can meet the needs of conducting systematic research on the Earth. However, a Moon-based platform has particular differences from space-borne and air-borne platforms because of its long distance from the Earth and the vast expanses of the Moon. In this article, we present three contributions. First, we propose a formula to describe the relative position of the Moon-based platform and Earth observation target. Second, we establish an observation geometry model and discuss three key observation parameters that are vital to the observation scope and coverage calculation. Third, a new observation scope and coverage analysis method is established in order to demonstrate that a suitable Moon-based Earth observation platform site can be located in the full observation region. We establish a geometric model for a Moon-based platform based on the Earth orientation parameters and Jet Propulsion Laboratory (JPL) ephemerides. Then, three key parameters including the visibility of the Earth from the Moon, nadir point, and Earth viewing angle are calculated using the proposed model. These parameters determine the observation scope and coverage of the Earth. The Earth-facing hemisphere of the Moon is divided into four regions, including the full observation region and the incomplete observation regions. Compared with the selenocentric case, during orbital periods, the maximum nadir point’s latitudinal and longitudinal difference in terms of placing sensors on the Moon surface is about 0.3°, the maximum viewing angle difference of the Earth is about 0.005°, and the maximum angular difference of the Moon-based platform and the Sun is about 0.24°. Thus, the maximum coverage difference is about 0.1%, so that placing sensors on the full observation region would result in better Earth observation performance. [ABSTRACT FROM AUTHOR]

Large-scale geoscience phenomena are increasingly attracting more attention because of their great scientific and social significance. However, many existing earth observation systems lack the ability to conduct long-term continuous observations at a regional-to-global scale because of spatial and temporal coverage limitations and systematic bias. In this work, we propose a new platform, the moon, and discuss its potential and optical geometrical characteristics for observing large-scale geoscience phenomena. Based on the Jet Propulsion Laboratory ephemerides, the reference systems transformation and a simulation system of moon-based earth observations were developed. Numerous experiments were carried out and a series of simulation images are presented, which illustrate the wide swath and continuous observation characteristics of such a lunar observatory. In order to quantify the performance of moon-based earth observations, a simplified geometrical model was constructed and data were analyzed. The sublunar points were found to be unique parameters with the ability to characterize the relative positions between moon and earth. We also defined an effective coverage parameter for assessing the optical coverage ability of moon-based earth observations. The calculation showed that the average value of the introduced coverage parameter from 1960 to 2050 was 0.500, and the coverage remained stable in different years. Furthermore, the total daily visible time and repeated times of different positions on the earth surface are analyzed and the effect of different positions on the lunar surface of the observatory are evaluated. The result shows that such a moon-based approach could make significant contributions to the monitoring and understanding of large-scale geoscience phenomena. [ABSTRACT FROM PUBLISHER]

Moon-based Earth observations have attracted significant attention across many large-scale phenomena. As the only natural satellite of the Earth, and having a stable lunar surface as well as a particular orbit, Moon-based Earth observations allow the Earth to be viewed as a single point. Furthermore, in contrast with artificial satellites, the varied inclination of Moon-based observations can improve angular samplings of specific locations on Earth. However, the potential for estimating the global outgoing longwave radiation (OLR) from the Earth with such a platform has not yet been fully explored. To evaluate the possibility of calculating OLR using specific Earth observation geometry, we constructed a model to estimate Moon-based OLR measurements and investigated the potential of a Moon-based platform to acquire the necessary data to estimate global mean OLR. The primary method of our study is the discretization of the observational scope into various elements and the consequent integration of the OLR of all elements. Our results indicate that a Moon-based platform is suitable for global sampling related to the calculation of global mean OLR. By separating the geometric and anisotropic factors from the measurement calculations, we ensured that measured values include the effects of the Moon-based Earth observation geometry and the anisotropy of the scenes in the observational scope. Although our results indicate that higher measured values can be achieved if the platform is located near the center of the lunar disk, a maximum difference between locations of approximately 9 × 10−4 W m−2 indicates that the effect of location is too small to remarkably improve observation performance of the platform. In conclusion, our analysis demonstrates that a Moon-based platform has the potential to provide continuous, adequate, and long-term data for estimating global mean OLR. [ABSTRACT FROM AUTHOR]

Spatio-temporal characteristics are the crucial conditions for Moon-based Earth observations. In this study, we established a Moon-based Earth observation geometric model by considering the intervisibility condition between a Moon-based platform and observed points on the Earth, which can analyze the spatio-temporal characteristics of the observations of Earth's hemisphere. Furthermore, a formula for the spherical cap of the Earth visibility region on the Moon is analytically derived. The results show that: (1) the observed Earth spherical cap has a diurnal period and varies with the nadir point. (2) All the annual global observation durations in different years show two lines that almost coincide with the Arctic circle and the Antarctic circle. Regions between the two lines remain stable, but the observation duration of the South pole and North pole changes every 18.6 years. (3) With the increase of the line-of-sight minimum observation elevation angle, the area of an intervisible spherical cap on the lunar surface is obviously decreased, and this cap also varies with the distance between the barycenter of the Earth and the barycenter of the Moon. In general, this study reveals the effects of the elevation angle on the spatio-temporal characteristics and additionally determines the change of area where the Earth's hemisphere can be observed on the lunar surface; this information can provide support for the accurate calculation of Moon-based Earth hemisphere observation times. [ABSTRACT FROM AUTHOR]

The solar invasion to an Earth observation sensor will cause potential damage to the sensor and reduce the accuracy of the measurements. This paper investigates the effects of solar invasion on the Moon-based Earth observation sensors. Different from the space-borne platform, a Moon-based sensor can be equipped anywhere on the near-side of the Moon, and this makes it possible to reduce solar invasion effects by selecting suitable regions to equip sensors. In this paper, methods for calculating the duration of the Sun entering of the sensor's field of view (FOV) and the solar invasion radiation at the entrance pupil of the sensor are proposed. By deducing the expressions of the proposed geometrical relationship between the Sun, Earth, and Moon-based platform, it has been found that the key parameter to the effects of solar invasion is the angle between the Sun direction and the line-of-sight vector. Based on this parameter, both the duration and radiation can be calculated. In addition, an evaluation approach based on the mean value and standard deviation has been established to compare the variation of solar invasion radiation at different positions on the lunar surface. The results show that the duration is almost the same wherever the sensor is placed in the permanent Earth-observation region. Further, by comparing the variation of solar invasion radiation at different positions on the near-side of the Moon, we suggest that equipping sensors on the mid–high latitude regions within the permanent Earth-observation region will result in less solar invasion affects. [ABSTRACT FROM AUTHOR]