Earth and Space Science最新文献

Hurricane Nicholas was classified as a Category 1 tropical cyclone (TC) at 0000 UTC on 14 September 2021 and made landfall along the upper Texas Gulf Coast at 0530 UTC with maximum sustained winds of 33 m s⁻¹. Much of the electrical activity during Nicholas was monitored by the Houston Lightning Mapping Array (HLMA) network. Thunderstorm activity developed in the rainband at 1700 UTC on 13 September, diminished by 2030 UTC, and re-intensified after 2200 UTC. At 2004 UTC (13 September), a curved megaflash (∼220 km) was observed by the HLMA in the stratiform precipitation region of the outer rainband. By 0130 UTC on 14 September 2021, vigorous storm cells developed in the eastern eyewall region and propagated cyclonically to the western eyewall region. At least four “jet-like” transient luminous events (TLEs) were observed by the HLMA emanating from a storm cell in the western eyewall region between 0230 and 0300 UTC with VHF source points ranging from 30 to 45 km in altitude. Moreover, the TLEs occurred within a region of strong wind shear, upper-level graupel-ice crystal collisions (∼15 km), and strong cloud top divergence. Charge analysis of the thunderstorm activity during Nicholas revealed an overall normal dipole structure, while the megaflash and TLE cases exhibited inverted dipole charge structures. Dissipation of the upper-level screening charge layer resulting from cloud top divergence likely played a role in the observed TLE VHF sources escaping to altitudes exceeding 30 km.

The Tibetan Plateau (TP) is covered by numerous lakes, and lake surface water temperature (LSWT) is an essential indicator of climate change, while few observations hinder our understanding of LSWT variation and its causes over TP. This study aims to simulate the summer LSWT long-term trends of 81 TP lakes during 1980–2018 and quantify the impacts and contributions of atmospheric variables. Results show that TP lakes warmed with 0.32°C decade⁻¹ on average. Northern TP lakes warmed faster than the southern ones (0.44 vs. 0.16°C decade⁻¹) due to stronger trends of atmospheric variables and higher sensitive of colder lakes to atmospheric changes. 55 (67.9%) lakes of the total lakes studied in current work warmed slower than air due to weakened shortwave radiation (SW_↓). Attribution analysis suggests that the air warming and wetting over TP dominate lakes' warming. Regarding synthesis contributions, air warming contributed 79.3%, with increased surface air temperature (SAT) and downward longwave radiation (LW_↓) accounting for 41.6% and 37.7%, respectively, and air wetting indicated by increased surface specific humidity (SSH) contributed 39.0%, followed by a positive contribution (16.8%) from declined wind speed (WS). The negative contribution (−35.1%) from weakened SW_↓ nearly counterbalances the positive effects of increased LW_↓. 55.1% of the total synthesis contribution arises from the cross contribution through interactions among atmospheric variables and is mainly reflected in SAT and SSH, accounting for 26.8% and 24.8%, respectively. The findings enhance understanding of climate change impacts on lake systems and offer insights for lake resource management.

This study utilizes Interferometric Synthetic Aperture Radar (InSAR) to examine subsidence along the coastal strip of the Miami barrier islands from 2016 to 2023. Using Sentinel-1 data, we document vertical displacements ranging from 2 to 8 cm, affecting a total of 35 coastal buildings and their vicinity. About half of the subsiding structures are younger than 2014 and at the majority of them subsidence decays with time. This correlation suggests that the subsidence is related to construction activities. In northern and central Sunny Isles Beach, where 23% of coastal structures were built during the last decade, nearly 70% are experiencing subsidence. The majority of the older subsiding structures show sudden onset or sudden acceleration of subsidence, suggesting that this is due to construction activities in their vicinity; we have identified subsidence at distance of 200 m, possibly up to 320 m, from construction sites. We attribute the observed subsidence to load-induced, prolonged creep deformation of the sandy layers within the limestone, which is accelerated, if not instigated, by construction activities. Distant subsidence from a construction site could indicate extended sandy deposits. Anthropogenic and natural groundwater movements could also be driving the creep deformation. This study demonstrates that high-rise construction on karstic barrier islands can induce creep deformation in sandy layer within the limestone succession persisting for a decade or longer. It showcases the potential of InSAR technology for monitoring both building settlement and structural stability.

Previous 1-D spherically symmetric seismic modeling studies have shown that in the presence of a clathrate lid on Titan significant thermal profile differences result, particularly in comparison to a pure water ice shell. In turn, these thermal differences would lead to notable changes in the waveform amplitudes and seismic phase arrival times. In this study we investigate the feasibility of using surface waves dispersion to explore the structure of Titan's ice shell. We investigate the ability to measure and observe the frequency-dependent signals (0.003–0.100 Hz) and their utility in being able to detect existence of a methane-clathrate lid. We find that we are unlikely to resolve the clathrate-lid's existence using long-period techniques, and this could be a limitation for studying very thick ice shells ($��>�\approx �$ 20 km) of icy ocean worlds. We did resolve the frequency range of flexural waves transitioning to a Stoneley wave (mode) in the fundamental mode, and see a Rayleigh wave in the first overtone for a 100 km ice shell on Titan for a simulated quake.

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.