Earth and Space Science最新文献

Two years following the extreme rainfall event in Henan Province in July 2021, North China was struck by another significant rainfall episode in late July and early August 2023 (the “23.7” event). This recent event, surpassed only by the August 1963 deluge in Henan province, precipitated extensive disasters across the Beijing-Tianjin-Hebei region (BTH) over the North China Plain. Understanding the mechanisms underlying such extreme precipitation events, including moisture sources and atmospheric circulation patterns, in the context of synoptic-scale systems is crucial for accurate predictions and effective disaster mitigation in the future. To achieve this, this study utilized a vertically integrated water vapor transport method and a Water Accounting model to investigate the moisture sources and pathways of the “23.7” event. A systematic analysis of circulation patterns was also conducted based on the ERA5 reanalysis. The results showed that the western North Pacific and Indian Ocean contributed 38.1% and 18.6%, respectively, to the extreme rainfall over the BTH region. Additionally, terrestrial moisture sources contributed 16.59%, playing a significant role in the event. The stable and moisture-laden air was transported to the BTH due to the influence of binary tropical cyclones “Doksuri” and “Khanun,” as well as the western Pacific subtropical high-pressure system. Convergence and updraft dynamics trigger convective processes modulated by vortices and topography. The findings of this study help to build a deeper understanding of the formation processes and mechanisms behind such heavy rainfall, which provides insights for model predictions of similar high-impact low-frequency extreme rainfall events.

The exploration of multi-layer coupling mechanisms between earthquakes and the ionosphere is crucial for utilizing ionospheric precursors in earthquake prediction. A significant research task involves continuously tracking the spatio-temporal changes in ionospheric parameters, acquiring comprehensive seismic anomaly information, and capturing “deterministic” precursor anomalies. Based on data from the China Seismo-Electromagnetic Satellite (CSES), we enhance the Pattern Informatics (PI) Method and propose an Improved Pattern Informatics (IPI) Method. The IPI method enables the calculation of the spatio-temporal dynamics of electron density anomalies detected by the CSES satellite. The seismic signals in the electron density during earthquake on 2021 at Maduo are investigated in this work. The results show that: (a) Compared to original electron density images, the IPI method-derived models extract distinct electron density anomaly signals, regardless of the data whether are collected during descending (daytime) or ascending (nighttime) orbits, or across different time scales of change window. (b) The electron density anomalies appear about 40 days prior to the Maduo Mw7.3 earthquake. The evolution of these anomalies follows a pattern of appearance, persistence, disappearance, re-emergence, and final disappearance. Moreover, the evolution trends of the IPI hotspot images at daytime and nighttime are similar. These results suggest that the IPI method can capture the spatio-temporal trends of ionospheric parameters and effectively extract electronic precursors related to strong earthquakes.

Tropical cyclones (TCs) are one of the biggest threats to life and property around the world. Accurate estimation of TC wind hazard requires estimation of catastrophic TCs having a very long return period spanning up to thousands of years. Since reliable TC data are available only for recently decades, stochastic modeling and simulation turned out to be an effective approach to achieve more stable hazard estimates. In common practice, hundreds of thousands of synthetic TCs are generated first, then wind fields are reconstructed along synthetic TC tracks for hazard estimation. A Bayesian hierarchical modeling approach to the reconstruction of TC wind field is proposed. A modified Rankine vortex is adopted as the wind field model, of which the four free parameters are modeled simultaneously through a multi-output neural network as a latent process of the wind field. The four parameters are finally represented, spatially and temporally, by a set of neural network weights, The Bayesian model averaging technique is used for parameter estimation and wind field reconstruction, based on a ensemble of maximum a posteriori estimates of the set of weights. Together with previously proposed algorithm for synthetic TC simulation, a two-stage scheme for TC wind hazard estimation has been formed, which is based on best-track data only and thus is highly consistent. Application of this scheme to the offshore waters in the western North Pacific basin shows inspiring performance and great flexibility for various purposes of TC wind hazard estimation.

Hollows on Mercury are small (hundreds of meters - few kilometers), shallow (tens of meters), irregular depressions typically found in clusters, often associated with impact craters, and likely formed by the loss of volatile materials. While their exact formation process remains debated, various hypotheses suggest sublimation or space weathering. In this study, we analyzed the global distribution of hollows, exploring their spatial patterns and relationships with key geological features. Our findings challenge the idea that hollows arise from a single volatile-rich surface layer, suggesting instead that volatiles are dispersed throughout the crust. Hollows show no correlation with specific geological units or elevations, indicating no singular volatile source. Moreover, the transitory nature of hollows is suggested as they are rare in older, degraded craters but common in younger ones or older craters with deep-seated features, hinting at a link to the reworking of materials through impacts or volcano-tectonic activity.

The Tonga-Hunga volcanic eruption on 15 January 2022 at 04:14:54 UTC produced large perturbations in the lower atmosphere and ionosphere globally. We report that the long period (0.28–16.67 mHz) ionospheric disturbances followed the surface pressure perturbations, which traveled globally. Here, we analyzed the Global Positioning System (GPS) data to understand the propagation of long period ionospheric disturbances together with the pressure waves in the regions along a great circle passing through Tonga, and also in the polar sectors. We also infer the strong westward propagation of ionospheric anomalies from GPS sites in Australia. This response of the ionosphere to the surface pressure fluctuations could be a possible reason for the observed ionospheric perturbations in polar regions. Our results demonstrate that (a) the pressure wave irregularities propagated all over the globe with an average velocity of ∼320 m/s and stimulated the non-dispersive ionospheric perturbations with the same velocity, (b) the volcano ionospheric disturbances due to multiple eruptions lasted for more than 3 hr and are even noticed in the northern and southern polar regions, (c) the variation of amplitude of the ionospheric perturbations with distance from Tonga follows an exponential decay with some irregularities near the equator, and (d) a low-frequency surface pressure irregularity of 12 hr duration is observed nearly 36 hr before the main eruption.

Nitrate (NO₃⁻) deposition in polar ice sheets archives valuable information on past solar activity. However, interpretation of Antarctic ice core NO₃⁻ records as a proxy for past solar activity remains challenging due to multiple sources and processes controlling NO₃⁻ variability in ice core records. Here, we present a new high-resolution ice core NO₃⁻ record (1905–2005 CE) from coastal Dronning Maud Land, East Antarctica, to investigate the solar signal and other forcing factors/processes in controlling ice core NO₃⁻ variability. Our record exhibits significant periodicity in the range of 8–12 years frequency band during 1940–2005 CE, apparently identified as the signal of ∼11 year sunspot cycle; however, such signal was not detected in the previous interval during 1905–1940 CE. To address the discontinuous and/or obscured signals in the present ice core record and inconsistency among various Antarctica ice core records, we extended our investigations to 10 ice core NO₃⁻ records from various regions of Antarctica. Analysis of seven records for the common interval from 1738 to 1990 CE reveals dominant periodicities of 8–12 years, indicating solar forcing as a primary driver, followed by precipitation modulated by El Niño-Southern Oscillation and Pacific Decadal Oscillation. Further, our investigation reveals that the solar signal extracted from multiple records becomes undetectable when mean annual hemispheric sunspot numbers larger than 140, suggesting this is a threshold limit for detecting the solar signal. These findings will improve our present understanding of ice core NO₃⁻ records as a proxy for past solar activity.

To differentiate and understand drivers behind coastal ice cover trends and variability, we advance development of a model combining satellite, in situ, and teleconnection data along the shoreline of Earth's largest freshwater lake (Lake Superior). Previous studies suggest a regime shift in Lake Superior's ice cover starting in 1998. Our study includes seven years of new data and subsequent model analysis that provide new insight into characteristics of the post-1998 regime. In addition to providing a valuable extension to the historical ice cover record for this domain, we find the regime shift in coastal ice cover starting in 1998 is characterized by pronounced variability, and not simply a shift in pre-1998 trends. Our findings represent an important stepping stone for future ice and climate modeling not only on Lake Superior but across the entire Great Lakes region and in other global high-latitude coastal regions as well.

This study aims to develop an absolute model of contemporary Vertical Crustal Movements (VCM) and Vertical Land Movements (VLM) in an area of Poland based on GNSS solutions. Velocities at permanent stations were subjected to geological, tectonic, hydrological and mineral information analyses. Reliability analysis and estimation of velocities at individual GNSS stations, comparative analysis of results and spatial analysis were carried out. Vertical velocities were determined using four computational strategies. Daily satellite data in the ITRF2014 system collected from permanent GNSS stations of the Polish part of the ASG EUPOS system were obtained from the Polish Main Office of Surveying and Cartography. All the data were from the 2011 to 2021 time period (approx. 11 years) and obtained in Rinex format. Time series from the Precise Point Positioning (PPP) solution calculated using GipsyX software were used. The absolute vertical crustal velocities obtained for Poland mostly vary between +1.0 and −1.0 mm/yr, which is 95% of the values obtained within local extremes. This region of Poland can be considered tectonically stable and the developed VCM model correlates with the geological and tectonic structure of the region. Taking into account the influence of tectonics, geology, hydrology and location of mineral resources has allowed better interpretation of vertical velocities and correction of the associated model. The proposed computational strategy based on combining data sets developed by different methods gave good results.

Seismic imaging is one of the most powerful tools available for constraining the internal structure and composition of planetary bodies as well as enabling our understanding planetary evolution, geology, and distribution of natural resources. However, traditional seismic instrumentation can be heavy and voluminous, expensive, and/or difficult to rapidly deploy in large numbers. Distributed acoustic sensing (DAS) provides a promising new alternative given the ease of deployment, light weight and simplicity of fiber optic cables. However, the feasibility and best operational practices for using DAS for planetary exploration are not well-known. We examine the use of DAS with surface deployed fiber for planetary near-surface seismic exploration at two lunar geophysical analogue sites in San Francisco Volcanic Field. We compare DAS recordings to 3-component seismometer recordings and geophone shot recordings and determine empirical response functions for the DAS system with respect to the 3-component recordings. Shot sections of DAS and traditional seismic equipment compare well visually, with similar moveout of identifiable phases. DAS records first arrivals in good agreement with seismometers making them suitable for refraction work. Multichannel analysis of surface waves is performed on DAS records to estimate shallow shear velocities. The DAS has high spectral coherence with the horizontal components of ∼0.7 in the frequency band of the seismic shot energy. The empirical response functions are stable with amplitudes of ∼1.0–3.0 × 10⁻¹⁰ m per strain. Finally, the phase response is linear but not flat or zero. Our experiment demonstrates that there is potential for surface deployed DAS in planetary landscapes.