Earth and Space Science最新文献

Ordos Basin, one of the largest uranium resource areas in China, holds significant potential due to its favorable metallogenic geological conditions and promising potential. Early exploration efforts primarily targeted sandstone-hosted uranium deposits. Recently, the discovery of several large and super-large sandstone-type uranium deposits has revealed previously unrecognized uranium-bearing formations. However, these newly identified formations have yet to undergo systematic research on their geological conditions and metallogenesis processes, highlighting the urgent need for further investigation to advance metallogenic theory. Additionally, fault structures, which are critical to the metalization process, remain insufficiently described due to lack of comprehensive geophysical data. To bridge this gap, this study employs areal data to characterize the geophysical signatures of both traditional and newly discovered ore-bearing formations. The research delineates the distributions of primary and secondary faults, analyzes the characteristic of basement relief, and integrates basin evolution with key metallogenic factors utilizing gravity and magnetic exploration. Furthermore, the study identifies two promising metallogenic zones, offering essential insights to guide future exploration, resource development, and efficient exploitation strategies.

Satellite altimetry has been the major data source for marine geoid determination·and gravity recovery in recent decades. In general, altimetry-derived geoid and gravity anomaly models are typically released with a 1' × 1' gridding interval. However, their actual spatial resolution is far lower than the nominal ∼2 km level. Therefore, analyzing the marine geoid resolution capability from satellite altimetry observations is crucial for marine gravity recovery studies. The Surface Water and Ocean Topography (SWOT) Mission is a newly launched satellite using advanced radar technology to make headway in observing the·variability of water surface elevations, providing new information through along-track and across-track two-dimensional swath observations. Here, we present the analysis results of marine geoid resolution capability for both typical conventional nadir altimeters and the SWOT Ka-band radar interferometer (KaRIn) in 2° × 2° bins worldwide between 60°N and 60°S. We demonstrate the potential of SWOT KaRIn to capture along-track short-wavelength signals below 10 km and analyze the bin-based statistics of key marine geophysical factors correlated with this marine geoid resolution capability. Generally, SWOT KaRIn exhibits better marine geoid resolution capability over bins with large-scale seamounts or trenches.

Tibetan Plateau vortices (TPVs) are the major precipitation-producing weather system, which dominates the water supplies over the TP. Serial clustering is one of the basic features of TPVs and is closely related to the atmospheric intraseasonal oscillation of the TP. Through a database of TPVs derived from multiple reanalysis data sets, we investigated the spatiotemporal characteristics of TPV clustering (TPVC) and its connection with the atmospheric quasi-biweekly oscillation (QBWO). The TPV tracks from variant reanalysis data sets reproduced consistent features for TPVC. The database revealed that the TPVC primarily occurs during the warm season and exhibits significant interannual variability. TPV clustering frequently occurs during the positive phase of the QBWO, in which the TP emerges cyclonic anomalies at lower atmospheric levels and anticyclonic anomalies at upper levels. This configuration creates a baroclinic structure that favors the formation of TPVCs. Conversely, the negative phase of QBWO results in an inverse atmospheric anomaly pattern, reducing TPVC occurrences. The interannual variability of TPVCs is primarily influenced by the amplitude of relative vorticity rather than the frequency of positive or negative phases. Furthermore, there are distinct differences in circulation patterns between years with high and low TPVC frequencies. In high-TPVC (low-TPVC) years, the lower levels of the TP predominantly show positive (negative) vorticity anomalies, accompanied by an anticyclone (cyclone) in the northern TP and a cyclone (anticyclone) in the eastern TP, while an anti-cyclonic (cyclonic) anomaly is active over the TP that indicates an intensified (weakened) South Asian High.

After over a half-century of development, bathymetric lidar is a mature and widely used technology for mapping the littoral zone in support of nautical charting, benthic habitat assessment, inundation modeling and other applications. In 2018, bathymetric lidar transitioned from a purely airborne technology to also a spaceborne capability with the launch of NASA's ICESat-2 satellite. An important aspect of obtaining accurate seafloor elevations and horizontal coordinates in bathymetric lidar is refraction correction, which corrects for the change in the speed and direction of the laser at the air-water interface. Unfortunately, data on the refractive index of seawater needed for correction are largely lacking, especially over global extents, which are required for ICESat-2 bathymetry. This study developed and evaluated a new global refractive index of water data layer. A two-phased sensitivity analysis was conducted to investigate how systematic and random uncertainties in the refractive index layers impact bathymetric lidar uncertainty. We then developed the global refractive index of water layer using global marine data sets and evaluated it using a combination of Argo Float data and in situ refractometer measurements. The results provide a strong indication of the usefulness of the global refractive index layer, which is currently being implanted into the workflow for generating a new ICESat-2 bathymetric data set (ATL24). To benefit other studies, the global refractive index layer is publicly available. Future improvements are possible, leveraging crowd-sourced data collection to continually improve the spatial resolution and nearshore accuracy of the refractive index data set.

Routine ground-based measurements of total ozone column (TOC), as well as ozone profile soundings started in the late 1960s in Germany. The resulting ozone and temperature records at Hohenpeissenberg and Berlin/Potsdam/Lindenberg show long-term changes similar to other stations in Central Europe, and to the changes seen globally. Following the increase of ozone depleting substances (ODS), stratospheric ozone has declined from the 1960s until the 1990s. Since about 2000, ozone has leveled or slightly increased, consistent with declining amounts of ODS. The stratosphere has been cooling and the troposphere has been warming, in agreement with general expectations due to increasing greenhouse gas concentrations. The clearest signs of recovering ozone are seen around 40 km altitude. Two factors contribute to this increase: the decrease of stratospheric chlorine loading and cooling of the upper stratosphere, which slows gas-phase ozone destruction cycles, and enhances the ter-molecular reaction producing ozone. Tropospheric ozone has increased substantially from the 1960s to the early 1990s. Since then, it has remained more or less constant, on a level higher compared to the 1960 and 1970s. Particularly low tropospheric ozone was observed in 2020, due to reduced precursor emissions during the COVID-19 related lockdowns. The atmospheric concentrations of greenhouse gases will likely continue to rise, while the concentrations of ozone depleting substances are expected to slowly decline. To see how the atmosphere responds, and to help understand future changes, continued monitoring will be required for many years to come, both over Germany and worldwide.

In this concept study, we explore coded aperture imaging as a high-angular resolution imaging technique for suprathermal electron strahl observations in the solar wind. In particular, studying the relative contribution of pitch-angle scattering to solar wind strahl broadening near 1 AU requires very high-resolution observations of electron pitch angle. Coded aperture imaging is advantageous because it is a high-signal method that can provide high-angular resolution observations from a simple, and compact platform. In this study, we present an initial design concept to achieve a 40$��°�$ field-of-view with 3.1$��°�$ angular resolution from a CubeSat-sized platform. We include an “egg-crate” collimator design to mitigate the impact of the partially coded field-of-view as well as block solar photons. We also describe an estimate of the instrument data production and a possible CMOS candidate for low energy energetic particle detection. Finally, we present initial results of simulated strahl in Geant4 and the instrument response to these distributions. We find that reconstructed distributions can have accurate estimates of the strahl width. However, we find that especially for more broad strahl observations, coded aperture artifacts diminish the reconstruction quality and result in large deviations between input and output distributions. Possible options to improve accuracy include increasing integration time or reducing energy resolution.

Turbulent processes in the atmospheric boundary layer (ABL) are parameterized in numerical weather prediction and climate models. Better understanding their modulation by larger-scale organized structures, some of them being represented explicitly, is thus of great interest. In this study, we test an innovative statistical tool, the Wavelet Scattering Transform (WST) on turbulent measurements of 3D velocities at different levels in the ABL during the $��{\text{EUREC}}^4�$A campaign near Barbados. The measurements were done in trade wind environment over the sea. They encompass two categories of ABL convection, roll vortices (RV) or convective cells (CC) whose organization depends on cold pool and density currents. Statistical tools such as Fourier transforms or moment analysis give access to levels of energy, characteristic sizes and variances in CC and RV conditions. The WST provides further information, with strong modulations of the turbulent scales by submeso- to mesoscales in CC, whereas modulating scales are smaller than the horizontal scale of rolls in RV. Penetrating dry tongues from the ABL top are revealed by modulation scales varying with height. In RV conditions, modulations differ in cross-wind and along-wind observations confirming that along-wind measurements do not provide good sampling of the ABL turbulence. WST are a valuable tool for investigating ABL turbulence and its interactions with coherent structures, and could be used on scalar variables and surface fluxes.

CO₂ concentration was continuously measured at four levels in the below-canopy layer of a subtropical evergreen broadleaf forest in Southeast China. The below-canopy CO₂ concentration was higher during the day than at night at all levels, in contrast to many previous studies. The amplitude of the diurnal variation of the below-canopy CO₂ concentration was controlled by the daily-mean air or soil temperature. In the daytime, solar radiation heated the canopy layer more than the below-canopy layer, so the below-canopy layer became stable. Large vertical gradients of CO₂ concentration therefore developed near the ground surface. CO₂ concentration increased with stability when the stability was weak, because the increased stability suppressed the vertical turbulent mixing. On the contrary, CO₂ concentration decreased with stability when the stability was strong, because the strong stability was maintained by intense solar radiation, which enhanced photosynthesis. In the nighttime, radiative cooling of the canopy layer caused the below-canopy layer to be near-neutral or unstable. CO₂ concentration was therefore generally low and exhibited rather small vertical gradients. Nighttime CO₂ concentration slightly increased when the stability became stronger. It was frequently observed that CO₂ concentration rapidly decreased around the sunset from the peak value to a low value. Our results suggest that the storage term is important in the daytime eddy-covariance measurements, and the CO₂ concentration above the canopy should be corrected in order to represent the CO₂ concentration below the canopy.

Shallow convective clouds (SCCs) play important roles in the Earth system. Previous studies mostly focus on SCCs over the oceans or plains. It is unclear how topography affects SCCs. In this study, the impacts of isolated ridges on the development of SCCs are investigated using large-eddy simulations, where the maximum height and the half-width of the ridge are systematically varied. In all simulations, the potential temperature over the ridge top is higher than over the plain, and the difference increases with the volume of the ridge. Upslope winds are only produced in simulations where the maximum slope angle is >0.5°. The vapor transport by upslope winds tends to increase the humidity over the ridge top. On the contrary, the dry air entrained from above the convective boundary layer tends to decrease the humidity over the ridge top. The upslope winds from the two sides of the ridge collide near the ridge top. This produces wide updrafts, and thereby facilitates the development of SCCs. As the ridge geometry varies, the variation of the depth of SCCs is collectively determined by the variations of the temperature, humidity, and updrafts. The depth of the SCCs increases with the maximum height of the ridge. It also increases as the half-width increases from 2 to 8 km, but only slightly changes as the half-width further increases to 16 km. The results of this study can potentially be used to implement the topographic effects in the parameterizations of SCCs.