Small cumulus clouds over the western United States were measured via airborne instruments during the wildfire season in summer of 2018. Statistics of the sampled clouds are presented and compared to smoke aerosol properties. Cloud droplet concentrations were enhanced in regions impacted by biomass burning smoke, at times exceeding 3,000 cm-3. Images and elemental composition of individual smoke particles

Drought conditions significantly impact human and natural systems in the Tropics. Here, multiple observational and reanalysis products and ensembles of simulations from the Coupled Model Intercomparison Project Phase 5 (CMIP5) are analyzed with respect to drought areal extent over tropical land regions and its past and future relationships to the El Niño/Southern Oscillation (ENSO). CMIP5 models forced

Many features on planetary bodies follow a distinct size-frequency distribution (SFD), and there are practically always outliers. In impact crater studies, that SFD can be approximated with a power-law, and the nature of power-laws is there are often lone, singular largest features. An open question is whether these largest features are truly anomalous, or whether they emerge as a statistical feature

The present study aims to map forest canopy height by integrating ICESat-2 and Sentinel-1 data and investigate the effect of integrating forest canopy height information with Sentinel-2 data-derived spectral variables on the prediction of spatial distribution of forest aboveground biomass (AGB). Random forest (RF) algorithm was used to develop forest canopy height and AGB models. It was observed that

Possible roles of large-scale precipitation on model simulations of the Madden-Julian Oscillation (MJO) were investigated using the Large-scale Precipitation Tracking (LPT) method. Individual LPT systems and eastward propagating MJO LPT systems were identified in both observations and 25 general circulation model (GCM) simulations. LPT systems show dominant eastward propagation over the Indian Ocean

This study reports a relation between electron flux modulations and chorus emissions by using correlation analysis. On April 18, 2017, Arase observed an enhancement of electron fluxes and intensification of banded chorus emissions at the same time. A result of the analysis shows that both the upper-band and lower-band chorus emissions have good correlations with field-aligned electron fluxes that satisfy

Projections of the winter North Atlantic circulation exhibit large spread. Coupled Model Intercomparison Project archives typically provide only a few ensemble members per model, rendering it difficult to quantify reducible model structural uncertainty and irreducible internal variability (IV) in projections. We estimate using the Multimodel Large Ensemble Archive that model structural differences

Radiocarbon (∆14C) measurements suggest the deep ocean stores marine dissolved organic carbon (DOC) on millennial timescales. The mechanisms that mediate this residence time remain unconstrained. Solid-phase extraction (SPE) has emerged as a widely used technique to isolate DOC for subsequent analyses. We present SPE-DOC concentrations and ∆14C values for three GO-SHIP Repeat Hydrography transects

Glacial ice from the last major advance covered the state of Connecticut and reached its glacial maximum on Long Island ∼21,000 years ago. As glacial ice melted and retreated northward, meltwater streams deposited sediments, like gravel, sand, silt, and clay, in low-lying areas. Many periglacial lakes formed in central Connecticut as meltwater accumulated into valleys that were dammed by ice or glacial

The radial viscosity of the mantle is generally thought to increase by ∼10-100 times from the upper to lower mantle with a putative, abrupt increase at 660 km depth. Recently, a low viscosity channel (LVC) between 660 and 1,000 km has been suggested. We conduct a series of time-dependent flow models with viscosity either increasing or decreasing at 660 km depth while tracking slab structure, state-of-stress

Abstract The plastic zone of the roof surrounding rock continues to expand after the coal seam mining. The permeability of the surrounding rock under plastic flow is a basic project for water inrush prevention in coal mine. In this work, the permeability experiments were carried out on roof sandstone from Xiaojihan No.2 coal seam under three loading paths. The variations of permeability affected by

Evaporites occur in various geological environments: sedimentary basins, orogenic belts, where they often act as tectonic decoupling layers, and as top-seals in hydrocarbon fields. In all cases, they affect the temperature distribution in the upper crust, as their thermal conductivity is relatively higher with respect to other sedimentary rocks. High heat conduction through evaporites enhances the

It is generally agreed that the Last Interglacial (LIG; ∼130 – 115 ka) was a time when global average temperatures and global mean sea level were higher than they are today. However, the exact timing, magnitude, and spatial pattern of ice melt is much debated. One difficulty in extracting past global mean sea level from local observations is that their elevations need to be corrected for glacial isostatic

The (effective) elastic thickness of the lithosphere defines the strength of the lithosphere with respect to a load on it. Since the lithosphere is buoyant on a viscous mantle, its behaviour with respect to a load is not fully elastic, but rather viscoelastic. Fennoscandia is a well-known area in the world where the lithosphere has not yet reached its isostatic equilibrium due to the ongoing uplift

We propose a new Bayesian approach to estimate continuous crustal strain-rate fields from spatially discrete displacement-rate data, based on Global Navigation Satellite System (GNSS) observations, under the prior constraint on spatial flatness of the strain-rate fields. The optimal values of the hyperparameters in the model of strain-rate fields are determined by using Akaike's Bayesian Information

The Sea of Marmara is a tectonically active basin that straddles the North Anatolian Fault Zone (NAFZ), a major strike-slip fault that separates the Eurasian and Anatolian tectonic plates. The Main Marmara Fault (MMF), which is part of the NAFZ, contains an approximately 150 km long seismotectonic segment that has not ruptured since 1766. A key question for seismic hazard and risk assessment is whether

The exposure of gabbroic sequences at Oceanic Core Complexes (OCC) along ultraslow- to slow-spreading ridges permits the study of the processes forming the lower oceanic crust. On top of the Atlantis Bank OCC along the ultraslow-spreading Southwest Indian Ridge, IODP Expedition 360 drilled Hole U1473A, mainly composed of primitive olivine gabbros interspersed with more evolved Ti-Fe oxide-bearing gabbros

In the present paper, the variabilities and long-term trends of summer monsoon rainfall for different intensity bins (dry, low, moderate, high, very high, and extreme) are studied for five homogeneous regions, namely Northeast India (NEI), Northcentral India (NCI), Northwest India (NWI), Westcentral India (WCI), and Peninsular India (PI) for 118 years (1901–2018). The study was carried out based on

Vladivostok city and its surrounding areas have previously experienced rainfall-induced landslides, which have caused significant casualties and damage in high-density urban areas. As a result of anthropogenic factors, steep slopes in some areas reach 90°, which significantly affects the slope stability. The authors collected all available historical data about landslide incidents in the study area

Metallic yielding damper is widely utilized to improve the seismic resilience of steel moment-resisting frames. It is a kind of displacement-depended damper and may fail when the ultimate displacement is reached under strong earthquakes. Nevertheless, little research has considered the damper failure behavior in seismic loss assessment of damper-retrofitted steel frames. In this paper, three representative

An anchored pile structure is a type of retaining structure that is widely used in excavation support systems, water-front structures, slope stabilization, and landslide prevention. This structure has good performance because the anchor can limit the displacement and control the deflection of the pile head. Field observations of the performance of various retaining structures during many recent earthquakes

Vulnerability functions describe the expected loss for a given ground shaking intensity level and are an essential component in probabilistic seismic risk assessment. This manuscript presents a novel open-source platform for the derivation of analytical fragility and vulnerability models, covering state-of-the-art methodologies, and addressing critical issues in vulnerability modelling such as uncertainty

Chemical-assisted steam flooding (CASF) is a promising method for heavy oils. However, few researches have investigated the CASF performance on offshore heavy oil reservoirs recovery after water flooding. In this study, a numerical simulation model was developed to simulate CASF processes for offshore heavy oil reservoirs after water flooding. Then, a comparison of CASF and various thermal methods

Water invasion is a common occurrence in multilayer unconsolidated gas reservoirs, which results in excessive water production and reduces the economic life of gas wells. However, due to multiple layers, active edge water, and strong heterogeneity, the mechanism of water invasion and its effect in the unconsolidated sandstone gas reservoir require understanding in order to improve efficiency and minimize

Qinzhou-Hangzhou metallogenic belt is an important polymetallic (Cu, Mo, W, Sn, Pb, Zn, Au, and Ag) belt in South China. The Xinmin polymetallic deposit is located in the southwestern segment of this belt, which ore bodies hosted in the contact zone of granite and Lower Devonian sedimentary strata and in the structure fractured zone within the strata. Three hydrothermal stages can be distinguished:

The formation of mud volcanoes/mud diapirs is directly related to oil and gas accumulation and gas-hydrate mineralization. Their eruptive activities easily cause engineering accidents and may increase the greenhouse effect by the eruption of methane gas. Many scholars have performed much research on the developmental characteristics, geochemistry, and carbon emissions of mud diapirs/mud volcanoes,

An ionogram is a graph of the time that a vertically transmitted wave takes to return to the earth as a function of frequency. Time is typically represented as virtual height, which is the time divided by the speed of light. The ionogram is shaped by making a trace of this height against the frequency of the transmitted wave. Along with the echoes of the ionosphere, iono- grams usually contain a large

Abstract A significant number of modern earthquake prediction algorithms are based on general signs of loss of stability by the system, without reference to the physical mechanism behind the development of seismic instability. Considerations have been repeatedly expressed that such an approach is unlikely to lead to a completely satisfactory forecast. New geophysical evidence in favor of a fluid metamorphogenic

Abstract In the winter months of 2018–2020, the Kola Branch of the Federal Research Center Geophysical Survey of the Russian Academy of Sciences (FRC GS RAS) carried out experiments on recording acoustic signals from triggered snow avalanches using infrasonic sensors. The purpose of the experiments was to assess the possibility of recording avalanches by the infrasound method in difficult Arctic conditions

Abstract The algorithms regularly used in electrical exploration for solving the inverse problem of vertical electrical sounding (VES) can lead to large systematic distortions of the results from equivalent models. The problem is significantly aggravated when interpreting data from precision geoelectrical monitoring, in particular, during long-term observations by VES. In such cases, it is necessary

Abstract The article substantiates the prospective application of Precise Point Positioning (PPP) satellite positioning technology for high-precision navigation support of geophysical surveys, especially when performed in hard-to-reach regions and over water areas. An experimental technique is proposed for studying PPP technology using a mobile research laboratory (MRL) mounted on a car and assessing

Abstract We conducted archaeoseismological studies at the Djanavara Monastery Complex in 2019. It consists of early medieval buildings of different ages, the main of which was the church. The church and the atrium were first badly damaged and then destroyed. There were attempts to repair them, as evidenced by the laying of a doorway in the north wall of the atrium. The age of this seismic event may

Abstract The article presents a new electric exploration measuring complex with pseudonoise sounding signals. The complex is designed for sounding of the Earth’s crust using transient electromagnetic methods. The technical characteristics of the complex and results of the first field experiments in the territory of the Bishkek geodynamic test area are presented. The tasks are set to improve the technical

Abstract Positioning and synchronization of seismic stations using GPS receivers is convenient and has sufficiently high accuracy for subsequent processing and adequate interpretation of the obtained seismic data. However, it is impossible to synchronize a seismic station at the time of data acquisition if it is outside the access area of GPS satellites, e.g., in a deep mine, such that the receiver

Abstract The article provides a generalized retrospective of creating global models of the Earth’s gravity field using satellite methods and modern global ultra-high-degree models; the most promising new solutions are considered. The main attention is given to reviewing techniques that affect the resolution of satellite methods, their development, and ways of further improvement. Modern combined models

Abstract The article gives the upper estimates for errors in determining the time of occurrence of earthquakes (origin time) τ0 and the ratio of the velocities of longitudinal and shear wave g propagating from earthquakes. The study also considers cases when the origin time is considered known and the ratio of longitudinal and shear wave velocities is known. The article draws two main conclusions.

Abstract The paper presents the results of tiltmeter observations on the Kamchatka Peninsula in 2012–2016. Of the six tiltmeter stations operating in this period, two were successful, located in the area of the Klyuchevskaya volcano group, where tiltmeters were installed taking into account the technical requirements. During the period under consideration, two significant geodynamic events occurred

Stability prediction of rock slopes under seismic loads is important for landslide hazard assessment. For this work we designed and built a model of a slope with a middle locked segment. To investigate its dynamic response characteristics and instability criteria under the influence of an earthquake, comparative experiments on a large-scale shaking table were performed. The results show that the acceleration

Fluid pressurization of critically stressed sheared zones can trigger slip mechanisms at work in many geological processes. Using discrete element modeling, we simulate pore-pressure-step creep test experiments on a sheared granular layer under a sub-critical stress state to investigate the micromechanical processes at stake during fluid induced reactivation. The global response is consistent with

GPS total electron content (TEC) measurements were used to investigate high-m ultralow frequency (ULF) waves during the recovery phase of a geomagnetic storm. ULF wave signals in TEC data show high coherence and significant common power in the wavelet coherence and cross wavelet transform analyses with magnetic field radial component data from GOES-15. They did not cause significant ionospheric scintillation

We present dayside electron temperature (Te) and density altitude profiles at Mars from MAVEN satellite deep-dip orbits. The data are after recalibration of the Langmuir Probe and Waves instrument that results in reduced uncertainties to as low as ±82°K. At MAVEN's lowest altitudes, (∼120–∼135 km), the measured values of Te are, after uncertainties, higher than those predicted by several modeling efforts

During early boreal summer 2020, the western North Pacific (WNP) was characterized by record-low tropical cyclone (TC) activity, reaching the lowest historical level since 1979. Only one short-lived TC was observed in June and the whole of July underwent an unprecedented quiescent TC period. Concurrent Indian Ocean warming provided unfavorable conditions for cyclogenesis over the WNP, which partly

Determining how electrons behave in whistler waves is fundamental for understanding whistler waves’ role in space electron energization. Here, we report a whistler wave-electron interaction case observed by Magnetospheric Multiscale spacecraft in the solar wind. The observations suggest whistler waves can effectively trap/bunch thermal electrons. In the direction perpendicular to the background magnetic

MgSiO3 majorite is the most significant endmember of the Al-deficient majorite garnets that form at depths higher than ∼400 km, in the mantle transition zone (MTZ). Here, we report elastic wave velocity measurements on polycrystalline MgSiO3 majorite samples, up to 18.4 GPa and 2000 K by ultrasonic interferometry techniques combined with in situ X-ray diffraction measurements in a multianvil apparatus

Cloud-to-ground strokes, narrow bipolar events, and energetic in-cloud pulses are known classes of high peak-current lightning processes that occur in thunderstorms. Here, we report one more distinct class of high peak-current events observed exclusively over mountainous terrain, usually above 2,000 m altitude, in the continental Unites States. These events, which we call mountain-top energetic pulses

We analyze the past 67,000 years of climate using Antarctic ice-core records to constrain the mechanisms involved in (a) the “bipolar seesaw” relationship between Greenland and Antarctic surface temperature variations, and (b) mechanisms of millennial-scale atmospheric CO2 concentration variations. Specifically, we determine for each Greenland Stadial the rate of Antarctic temperature and atmospheric

Earth system modeling of climate geoengineering proposals suggests that the physical outcomes of such interventions will depend on the particulars of the implementation. Here, we present a first attempt to “geoengineer” a well-known teleconnection between sea surface temperatures (SSTs) and Sahelian precipitation. Using idealized earth system model simulations, we show that selectively cooling the

Elastic full-waveform inversion (EFWI) updates high-resolution model parameters by minimizing the misfit function between the observed and modeled data. EFWI possesses strong nonlinearity and is likely to converge to a local minimum when the inversion begins with inaccurate initial models. Elastic reflection waveform inversion (ERWI) recovers the low-wavenumber components of P- and S-wave velocities

Identifying thinly bedded reservoirs is important in exploration, appraisal, and development. The thin beds that we are referring to are of meter scale or less. Conventional seismic attributes are not able to resolve thin-bed effects. A new frequency-dependent amplitude variation with offset (FAVO) seismic attribute is developed for the prediction of thin beds. It is based on seismic wave scattering

Compared with isotropic media, at least two extra parameters are involved in common P-wave seismic data processing and interpretation for transversely isotropic media. Previous synthetic model testing has shown that it is challenging to estimate anisotropy parameters even using extremely low noise level seismic data from a simple geologic setting. Although theoretically independent, anisotropy parameters

Describing and understanding the basement relief of sedimentary basins is vital for oil and gas exploration. The traditional method to map an interface in each spatial direction is based on 3D modeling of gravity Bouguer anomalies with variable lateral and vertical density contrasts using a priori information derived from other types of geoscience data sets as constraints (e.g., well and/or seismic

Underground traffic activities spread ground-borne vibrations in a complex way. The present work focuses on 173 individual vehicles tracked as moving sources of vibrations in the Mont Terri rock laboratory, located 95 m away from a motorway tunnel. Two neighboring geophones record the vertical ground velocity of traffic-induced events with peak particle velocities ranging in 0.15-0.35 m/s. A dynamic

Located in the northern end of the Manila Trench, the deformation front (DF) off southwestern Taiwan is considered as a potential area for generating hazardous earthquakes and tsunamis. However, this area has been relatively seismically quiet, and the seismogenic structure has been unclear, particularly in the middle-to-lower crust. On February 10, 2017, an Mw5.3 earthquake occurred in the near-shore

Wudalianchi volcano is one of the youngest volcanic groups among the Cenozoic intraplate volcanoes in Northeast China and is notable for its potassium-rich basalts. With newly deployed dense broadband seismic stations, we construct a high-resolution 3-D S-wave velocity model of Wudalianchi volcano and its adjacent region, including the Keluo and Erkeshan volcanoes, using ambient noise and teleseismic

Accuracy of an explicit traveltime-offset approximation affects the results of the velocity analysis that plays a crucial role in the seismic data processing. Seismic anisotropy is important to account for large offset and azimuth since it can provide detailed information comparing with the isotropic assumption. For the perturbation-based method, different traveltime approximation forms result in different

We address deviations in the source bearing of natural pulsed extremely low frequency (ELF) radio signals (Q-bursts) in the Schumann resonance band. The model of smooth day – night non-uniformity is used. The observer is located at the Ukrainian Antarctic station “Akademik Vernadsky” (65.25° S and 64.25° W), and the source is positioned at the same meridian at latitudes of 20° S; 25° N, or 85° N. The

The formation of uplifts in rift basins is generally controlled by fault-block tilting and/or regional uplift. The Beidagang Uplift, located in the middle part of the Qikou Sag of the Bohai Bay Basin, is an important hydrocarbon accumulation zone that has experienced a complex evolutionary history since the Cenozoic. In this study, we conducted apatite fission track (AFT) analysis and structural analysis

The glacier cover of the Hindu Kush Mountains of Afghanistan provides a natural laboratory to assess the impact of climate change on the cryosphere. However, to date, not much is known about how the cryosphere in these mountainous regions is responding to climate change. Therefore, using an integrated approach including geospatial technology, climate data, a mass balance study, as well as topographic