In this paper, the modifications of the whistler dispersion characteristics are investigated which arise if resonant electrons are taken into account. The following chain of processes is emphasized: Generation of whistler waves propagating at different angles to the magnetic field and their nonlinear interaction with resonant electrons result in the appearance of modulated electron beams in the background plasma. As a result, the dispersion characteristics of waves in this new plasma might be significantly changed. By solving the kinetic dispersion relation of whistler waves in electron plasmas with so-called beam/plateau (b/p) populations, the associated modifications of the whistler dispersion characteristics are presented in diagrams showing, in particular, the frequency versus propagation angle dependence of the excited waves. It is important to point out the two functions of the b/p populations. The interaction of the beam-shifted cyclotron mode ω = Ωe + k·Vb (Vb<0, Vb is the b/p velocity, Ωe: electron cyclotron frequency)) with the whistler mode leads to enhanced damping at the ω-k point where they intersect. This is the origin of the frequency gap at half the electron cyclotron frequency (ω~Ωe/2) for quasi-parallel waves which are driven by temperature anisotropy. Furthermore, it is shown that the upstream b/p electrons alone (in the absence of temperature anisotropy) can excite (very) oblique whistler waves near the resonance cone. The governing instability results from the interaction of the beam/plateau mode ω=k·Vb (Vb>0) with the whistler mode. Relations to recent and former space observations are discussed.

We use 148 airborne vertical profiles of CO2 for frontal cases from the summer 2016 Atmospheric Carbon and Transport-America (ACT-America) campaign to evaluate the skill of ten global CO2 in situ inversion models from the version 7 Orbiting Carbon Observatory-2 (OCO-2) Model Intercomparison Project (MIP). Model errors (model posterior-observed CO2 dry air mole fractions) were categorized by region (Mid-Atlantic, Midwest, and South), frontal sector (warm or cold), and transport model (predominantly Tracer Model 5 (TM5) and Goddard Earth Observing System-Chemistry (GEOS-Chem)). All inversions assimilated the same CO2 observations. Overall, the median inversion profiles reproduce the general structures of the observations (enhanced / depleted low-level CO2 in warm / cold sectors), but 1) they underestimate the magnitude of the warm / cold sector mole fraction difference, and 2) the spread among individual inversions can be quite large (> 5 ppm). Uniquely in the Mid-Atlantic, inversion biases segregated according to atmospheric transport model, where TM5 inversions biases were-3 to-4 ppm in warm sectors, while those of GEOS-Chem were +2 to +3 ppm in cold sectors. The large spread among the mean posterior CO2 profiles is not explained by the different atmospheric transport models. These results show that the inversion systems themselves are the dominant cause of this spread, and that the aircraft campaign data are clearly able to identify these large biases. Future controlled experiments should identify which inversions best reproduce midlatitude CO2 mole fractions, and how inversion system components are linked to system performance.

The short period fluctuations of the geomagnetic field observed in the secular acceleration have a strong presence near the equatorial region of the Earth. Origin of such fluctuations is believed to be the equatorially confined waves below the core-mantle boundary in the fluid outer core. The state of the outer core, being in a balance between the magnetic, Coriolis and buoyancy forces, can lead to the generation of such waves if a stably stratified layer exists in the outermost regions of the core. In this study, a shallow water magnetohydrodynamical model is used to investigate the characteristics of such equatorially trapped waves with a multilayered stratification and background magnetic field. A two-layer model is implemented to study the effects of radially varying background magnetic fields on the equatorially confined waves. Analytical derivation of the dispersion relation and numerical solutions have been performed to characterise these waves.The role of change in buoyancy frequency across the two layers in modifying the equatorially trapped waves is investigated.

Indonesia accounts for more than one third of the world’s tropical peatlands. Much of the peatland in Indonesia has been deforested and drained, meaning it is more susceptible to fires, especially during drought and El Niño events. Fires are most common in Riau (Sumatra) and Central Kalimantan (Borneo) and lead to poor regional air quality. Measurements of air pollutant concentrations are sparse in both regions contributing to large uncertainties in both fire emissions and air quality degradation. We deployed a network of 13 low-cost PM2.5 sensors across urban and rural locations in Central Kalimantan and measured indoor and outdoor PM2.5 concentrations during the onset of an El Niño dry season in 2023. During the dry season (September 1st to October 31st), mean outdoor PM2.5 concentrations were 136 µg m-3 , with fires contributing 90 µg m-3 to concentrations. Median indoor/outdoor (I/O) ratios were 1.01 in rural areas, considerably higher than those reported during wildfires in other regions of the world (e.g. USA), indicating housing stock in the region provides little protection from outdoor PM2.5. We combined WRF-Chem simulated PM2.5 concentrations with the median fire-derived I/O ratio and questionnaire results pertaining to participants’ time spent I/O to estimate 1.62 million people in Central Kalimantan were exposed to unhealthy, very unhealthy and dangerous air quality (>55.4 µg m-3 ) during the dry season. Our work provides new information on the exposure of people in Central Kalimantan to smoke from fires and highlights the need for action to help reduce peatland fires. 

Numerical experiments have revealed the importance of horizontal transport of light in the presence of clouds (“3D effects’), with consequences for climate, weather and solar resource availability predictions. Yet, atmospheric models continue to use 1D radiative transfer schemes. In this paper, we provide observational evidence for 3D effects. Observed direct and diffuse surface fluxes are compared to outputs from the ecRad radiative transfer scheme run on retrieved cloud profiles. The direct-beam calculation takes careful account of the field-of-view of the pyrheliometer to ensure consistency between observed and modeled direct fluxes. Only the solver that accounts for 3D effects is able to reproduce the observed mean direct–diffuse partition of surface fluxes as a function of solar zenith angle and cloud cover. This validates the physically-based model for 3D radiative processes included in ecRad. These results are in favor of a shift of paradigm from 1D to 3D radiation in large-scale models.

In forested, seasonally dry watersheds, winter rains commonly replenish water storage deficits in the vadose zone before recharging underlying hillslope groundwater systems that sustain streamflow. However, the relative inaccessibility of the subsurface has hindered efforts to include the role of storage deficits, primarily generated by plant-water uptake, in moderating groundwater recharge. Here, we compare groundwater recharge inferred from the storage-discharge relationship with independent, distributed estimates of vadose zone storage deficits across 12 undisturbed California watersheds, thereby tracking the evolution of the deficit-recharge relationship without intensive field instrumentation. We find accrued deficits during the dry season (driven by evapotranspiration) alone insufficiently explain differences in the wet season partitioning of rainfall due to the inter-storm behavior of the deficit during the subsequent wet season. Tracking the deficit at the storm event-scale within the wet season reveals a characteristic response in groundwater to increasing rainfall not captured in the seasonal analysis, and may improve estimates of the rainfall required to generate recharge and streamflow on a per-storm basis. Our findings demonstrate the potential for existing public datasets to better capture water partitioning within the subsurface using a combined deficit-recharge approach, though our analysis is currently limited to basins with select characteristics.

Innovative groundwater management strategies are essential to preserve aquifers for crop irrigation. In western Kansas, USA, irrigators self-organized to extend the aquifer’s lifespan by self-imposing groundwater pumping limits enforced over a five-year period. While the five-year groundwater allocation period granted irrigators additional flexibility, it adds a new temporal dimension to their decision-making beyond the typical annual/sub-annual cropping and irrigation decisions. Pumping restrictions, along with uncertain precipitation, complicate multi-year farm planning. We formulated a two-stage stochastic modeling framework to design optimal annual cropping and irrigation allocations under pumping restrictions and uncertain precipitation. Optimal cropping and allocation strategies by the stochastic optimization model significantly outperform observed farmer strategies during the first two five-year LEMA periods (2013-2022) but only outperformed the optimal strategy by the deterministic optimization model assuming long-term average precipitation during drier conditions. We show that optimal cropping decisions shift from predominately corn to sorghum if more stringent pumping restrictions are imposed. Furthermore, irrigators are better off to use less water in the earlier years and saving more water for later years under more stringent five-year pumping restrictions, while they should use more of their allocation earlier under less stringent pumping limits. Extending the duration of the groundwater allocation window allows additional operational flexibility and enhances profits but the marginal gains for each additional year drop off after around seven years. Our versatile modeling framework is applicable to other regions considering groundwater pumping restrictions with the aim of balancing water conservation with farmer profitability and adaptability.

We examined two tear faults, namely, Nos. 4 and 7 Faults, in Tarim Basin to investigate how a tear fault penetrates the salt layer. Using high-quality seismic data, we showed that No. 4 Fault penetrates the salt layer, whereas No. 7 Fault does not. We calculated the strata shortening data of Nos. 4 and 7 Faults. For No. 4 Fault, we observed shortening differences between the western and eastern sections in both the supra- and sub-salt strata, whereas for No. 7 Fault, we observed shortening differences only in the supra-salt strata. We demonstrated that under the action of thrusting, a tear fault could penetrate the salt layer if there is a shortening difference in the different positions of the sub-salt strata. A lack of shortening difference in the sub-salt strata implies that a tear fault cannot penetrate the salt layer, even though the sub-salt strata are deformed during thrusting.

To precisely describe the dynamics of vegetation cover in high-density urban areas, this study evaluates the spatial and temporal consistency of the Normalized Difference Vegetation Index (NDVI) from multiple satellite data sources. The study areas of Downtown Beijing target at two scales: the district scale, and the neighborhood scale. Results show that Planet, Sentinel-2, Landsat-8, and MODIS share a similar spatial pattern; Sentinel-2, Landsat-8, and MODIS correlate in the temporal change of NDVI at both spatial scales in 2019, but AVHRR does not present useful information of spatial patterns of urban green space or urban vegetation dynamics at these two scales. Seasonal contrast derived from Sentinel-2 and Landsat-8 can be visualized through seasonal variation ratio to assist urban green space planning. This study highlights the usefulness of existing satellite observations in monitoring a variety of urban greening typologies at the neighborhood scale for improving urban environmental planning.

Floods lead to adverse impacts not only in financial terms but also on the health of the exposed population. We report the health-related Quality of Life (QoL) and functioning in the population affected by the 2021 flooding in Germany using an empirical survey dataset collected in November and December 2022. Health-related QoL and functioning of flood-affected population is represented by two scores - 1. The EuroQoL 5D Visual Analog Scale (EQ-5D VAS) and 2. the score of the 12-Item WHO Disability Assessment Schedule (WHODAS) 2.0, respectively. By applying an incremental linear regression model and an ensemble of Machine Learning (ML) models, we infer that health-related QoL and functioning are strongly negatively related to the psychological burden from those being affected by the flood event. This includes how often they think about the traumatic event. Home owners were found to have worse QoL and functioning than tenants. Household income and ability to repair/reconstruct flood damages – in specific, insurance benefits, private donation and satisfactory claims compensation are associated with high QoL and functioning in flood-affected populations. These findings highlight the importance of strengthening the mental health of flood affected populations in order to help reduce the psychological burden of the flood event. Additionally, the study emphasizes the strong positive association between physical/financial recovery and QoL and functioning of flood-affected populations.

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 Indian Ocean efficiently increases precipitation in the Sahel region, widening the seasonally migrating rainband over Africa. Applying the SST perturbations derived from the idealized experiments to observationally constrained historical ones, we find that our intervention can reverse conditions as extreme as the mid-20th century Sahelian drought, albeit less efficiently than in the idealized simulations. Side effects include changes in the seasonal distribution of Sahelian precipitation and substantial precipitation reductions in sub-Saharan East Africa. This work represents a proof-of-concept illustration of effects that might be expected with a tailored, regional approach to climate intervention.

• New basis functions suitable for fitting ionospheric electrojet magnetic signatures are developed • The basis functions are constructed from principal components analysis of current loops in quasi-dipole geometry confined to the electrojet regions • The utility of these new basis functions is demonstrated by fitting them to multiyear Swarm satellite measurements of the ionospheric field

Reconstructing fluid evolution history in old sedimentary basins is extremely challenging due to the prolonged evolution, lack of exact age constraints and absence of preserved fluids. By integrating in-situ calcite U-Pb dating, fluid inclusion analysis, and high-resolution measurements of carbon-oxygen-strontium isotopes and rare earth elements (REEs), we have reconstructed the fluid evolution history in an Ordovician deeply-buried carbonate reservoir in the Tarim Basin, China with unprecedented temporal resolution. Five generations of calcite cementation spanning over 37 m.y. are dated in a single calcite vein with U-Pb ages ranging from ~353 Ma to ~316 Ma. The initial cement was associated with an intrusion of hyper-saline brine enriched REEs. This was followed by influx of meteoric water to precipitate the second and third generations of cement, characterized by a reduced salinity, anomalously high Sr isotopic ratios and extremely low concentrations of REEs. The fourth generation of cement was formed in a deep-fluid system accompanied by oil charge as indicated by the presence of bitumen, oil inclusions and lighter C and Sr isotope ratios. The fifth generation of cement was precipitated from an equilibrated connate water, having the lowest salinity and a comparable REE signature with the host rock. Oil charge was dated to be around 326 Ma. This study demonstrates the effectiveness in combining in-situ calcite U-Pb geochronology, fluid inclusion analysis and other geochemical analyses to elucidate high-resolution temporal fluid evolution in an old sedimentary basin with a complex tectonic history, providing a new paradigm for studying geofluid evolution.

Thirteen years of precipitation d2H, d18O, and 3H data for three western United States continental interior weather stations, supplemented with 60 years of precipitation data, have been analyzed. The stations are located 1,000 to 2,000 km from four ocean moisture sources. Precipitation was evaluated relative to storm track trajectory, the El Niño-Southern Oscillation Oceanic Niño Index (INO), orography, precipitation amount, air temperature, month, and season. The INO was not fond to correlate with precipitation flux or isotopic composition. Tritium deposition was evaluated relative to the ‘spring leak’, thunderstorms, surface evaporation, storm tracks, and seasons. Local meteoric water lines and the Global Meteoric Water Line were compared. Winter precipitation is isotopically depleted and summer precipitation is isotopically enriched. Factors affecting the stable isotopes include winter cold cloud temperature, summer rain droplet partial evaporation, gradual rain out, and multiple episodes of soil moisture re-evaporation and subsequent re-precipitation.

An unusual salt-rich (SR) and salt-poor (SP) fluid immiscibility (FFI) could occur in a variety of hydrothermal fluids. The segregation of SR fluid from SP fluid provides a potential mechanism for substantial mass enrichment during some ore forming processes. However, the physical properties of SR and SP fluids, which determine the hydrodynamic behaviors of unmixed fluids, have not been well constrained. This study adopted in situ optical observation, quantitative Raman analysis, and the mass conservation law to derive the density of the SR and SP fluids. On this basis, falling sphere viscometry was employed to determine the viscosity of the SR fluid. Results showed that SR fluid exhibited an obviously higher density but comparable viscosity to SP fluid, favoring its high mobility and strong tendency to segregate from SP fluid. Consequently, the FFI could contribute tremendously to mass enrichment during fluid evolution.

To complement the information provided by deterministic seismic imaging at length scales above a certain resolution limit we present the first application of Adjoint Envelope Tomography (AET) to experimental data. AET uses the full envelopes of seismic records including scattered coda waves to obtain information about the distribution of absorption and small-scale heterogeneity which provide complementary information about the investigated medium. Being below the resolution limit this small-scale structure cannot be resolved by conventional tomography but still affects wave propagation by attenuating ballistic waves and generating scattered waves. Using ultrasound data from embedded sensors in a meter-sized concrete specimen we image the distribution of absorption and heterogeneity expressed by the intrinsic quality factor Q-1 and the fluctuation strength ε that characterizes the strength of the heterogeneity. The forward problem is solved by modelling the 2-D multiple nonisotropic scattering in an acoustic medium with spatially variable heterogeneity and attenuation using the Monte-Carlo method. Gradients for the model updates are obtained by convolution with the back-propagated envelope misfit using the adjoint formalism in analogy to full waveform inversion. We use a late coda time window to invert for absorption and an earlier time window to infer the distribution of heterogeneity. The results successfully locate an area of salt concrete with increased scattering and concentric anomalies of intrinsic attenuation. The resolution test shows that the recovered anomalies constitute reasonable representations of internal structure of the specimen.

To confirm whether the uplift in Jigokudani valley between 2007 and 2010 detected by Interferometric Synthetic Aperture Radar has continued to the present, we conducted leveling survey since 2015. Most bench marks showed subsidence up to 5.6 cm from October 2016 to September 2020, while a bench mark locates at the center of the leveling route uniquely showed uplift. A crack with a length of 350 m, a width of 100 m, a dip of 61° and striking parallel to the old explosion craters is identified at a depth of 50 m near the center of Jigokudani valley. The estimated crack is located at a similar position of the gas chamber identified from the audio-frequency magnetotelluric survey. Opening of the crack turned to closing between 2017 and 2020 probably because of the increase in emission of volcanic fluid or gas with a formation of a new crater.

We analyzed OH airglow images observed from an all-sky camera at King Sejong Station, Antarctica for the period of 2012–2016. Using M-transform method, 2D-power spectra of short period waves (< 1 hr) were obtained from 107 image sequences. The power spectral densities evidently show that the mesospheric wave activity is the strongest during winter. We also constructed climatological wind blocking diagrams using horizontal winds obtained from MERRA-2 for the altitudes of = 10–64 km, and from KSS meteor radar data for = 80–90 km. The wind blocking diagrams are negatively matched with the dominant propagating directions of the observed slow speed waves (< 30 m/s), providing the graphical evidence of wind filtering effects. However, there are significant eastward waves in winter and strong south-eastward waves in spring that are not blocked by the stratospheric winds. We speculate that these waves may be generated from the upper stratosphere or mesosphere.