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We present a novel method to quantify the event‐specific spatial evolution of plasmaspheric hiss wave power using a Drift‐Diffusion model. Constrained by Polar Operational Environmental Satellites/Meteorological Operational Satellites data, the model simulates low‐altitude electron distributions, accounting for azimuthal drift, pitch‐angle diffusion, and atmospheric backscatter. Applying to an event on 15 October 2016, the model quantifies the spatial evolution of hiss waves at L = 3.9, which contributes to the steady decay of electron flux observed by Van Allen Probes (VAPs). The model reproduces local‐time dependent features and shows excellent agreement with hiss wave power observed by VAPs. The model shows increased wave power and spatial spread following increased activities in the AL‐index, consistent with previous statistical results. The model also suggests the presence of “low”‐frequency hiss, which was undetected by VAPs, likely masked by instrument noise. This is the first time low‐altitude measurements are used to quantify event‐specific wave distributions which include both diffusion and drift effects. Plain Language Summary We present a novel method to estimate the location and strength of plasmaspheric hiss waves in the Earth's magnetosphere during specific events. These waves play a critical role in shaping the dynamics of Earth's radiation belts by scattering energetic electrons into the atmosphere. However, directly measuring these waves everywhere in the magnetosphere is unfeasible given the inherent limited coverage of satellites. Our approach uses a Drift‐Diffusion model, a physics‐based simulation on how electrons behave in the presence of these waves, and through iteratively best‐fitting model to observations from Polar Operational Environmental Satellites/Meteorological Operational Satellites, we can quantify the free parameters in the model, such as wave power and its location. The model shows remarkable agreement with hiss wave observations from Van Allen Probes (VAPs) during an event on 15 October 2016. It also shows how the waves intensify and spread following increases in AL‐index activity, consistent with past statistical studies. The model also suggests the presence of “low”‐frequency hiss waves, though they were not detected by VAPs, likely due to instrument noise. This method provides a powerful tool to study wave activity in areas where direct measurements are unavailable. Key Points A novel method using a Drift‐Diffusion model constrained by Polar Operational Environmental Satellites/Meteorological Operational Satellites data estimates the event‐specific spatial evolution of wave power The model reveals increase in hiss wave power and spatial spread during high AL activity, consistent with previous statistical results The model suggests the presence of low‐frequency hiss waves during the event, though they were not observed by Van Allen Probes

The growth with fetch of young wind waves under steady wind forcing that is commonly attributed to shear flow instability results in a spatially inhomogeneous wave field with a spectrum evolving along the tank. The present laboratory study accounts for multiple co-existing statistically stationary random frequency harmonics. Single-point synchronous measurements of the instantaneous surface elevation and of its along-wind slope component are performed by optical methods at numerous locations. Assuming exponential spatial growth, the phase shift between the surface elevation and surface slope at each frequency is related to the spatial growth rate of each harmonic. The validity of the assumption that the wave energy varies exponentially with fetch is examined in a separate set of experiments; the instantaneous surface elevation at various wind-forcing conditions is measured at multiple locations along the tank. The spatial variation of the energy of individual frequency harmonics is determined. It is found that, below the local peak frequency, the energy of each harmonic grows exponentially, while the evolution of waves at frequencies approaching and exceeding the local peak is strongly affected by sheltering by the dominant wave, as well as by nonlinear bound waves. The outcomes of two independent methods of determination of spatial growth rates at a range of young wave frequencies are compared. The accumulated data also enable quantitative analysis of the sheltering phenomenon. The essential difference between the spatial and the temporal wind-wave evolution cases is discussed.

The theoretical model for group-forced infragravity (IG) waves in shallow water is not well established for nonbreaking conditions. In the present study, analytical solutions of the group-forced IG waves at O(β1) (β1 = hx/(Δkh), hx = bottom slope, Δk = group wavenumber, h = depth) in intermediate water and at O(β−11) in shallow water are derived separately. In case of off-resonance [β1μ−1 = O(β1), where μ=1−c2g/(gh) is the resonant departure parameter, cg = group speed] in intermediate water, additional IG waves in quadrature with the wave group forcing (hereinafter, the nonequilibrium response or component) are induced at O(β1) relative to the equilibrium bound IG wave solution of Longuet–Higgins and Stewart (1962) in phase with the wave group. The present theory indicates that the nonequilibrium response is mainly attributed to the spatial variation of the equilibrium bound IG wave amplitude instead of group-forcing. In case of near-resonance [β1μ−1 = O(1)] in shallow water; however, both the equilibrium and nonequilibrium components are ~O(β−11) at the leading order. Based on the nearly-resonant solution, the shallow water limit of the local shoaling rate of bound IG waves over a plane sloping beach is derived to be ~h−1 for the first time. The theoretical predictions compare favorably with the laboratory experiment by Van Noorloos (2003) and the present numerical model results generated using SWASH. Based on the proposed solution, the group-forced IG waves over a symmetric shoal are investigated. In case of off-resonance, the solution predicts a roughly symmetric reversible spatial evolution of the IG wave amplitude, while in cases of near to full resonance the IG wave is significantly amplified over the shoal with asymmetric irreversible spatial evolution.

Gravity waves (GWs) as well as solar tides are a key driving mechanism for the circulation in the Earth's atmosphere. The propagation of gravity waves is strongly affected by tidal waves as they modulate the mean background wind field and vice versa, which is not yet fully understood and not adequately implemented in many circulation models. The daylight-capable Rayleigh–Mie–Raman (RMR) lidar at Kühlungsborn (54∘ N, 12∘ E) typically provides temperature data to investigate both wave phenomena during one full day or several consecutive days in the middle atmosphere between 30 and 75 km altitude. Outstanding weather conditions in May 2016 allowed for an unprecedented 10-day continuous lidar measurement, which shows a large variability of gravity waves and tides on timescales of days. Using a one-dimensional spectral filtering technique, gravity and tidal waves are separated according to their specific periods or vertical wavelengths, and their temporal evolution is studied. During the measurement period a strong 24 h wave occurs only between 40 and 60 km and vanishes after a few days. The disappearance is related to an enhancement of gravity waves with periods of 4–8 h. Wind data provided by ECMWF are used to analyze the meteorological situation at our site. The local wind structure changes during the observation period, which leads to different propagation conditions for gravity waves in the last days of the measurement period and therefore a strong GW activity. The analysis indicates a further change in wave–wave interaction resulting in a minimum of the 24 h tide. The observed variability of tides and gravity waves on timescales of a few days clearly demonstrates the importance of continuous measurements with high temporal and spatial resolution to detect interaction phenomena, which can help to improve parametrization schemes of GWs in general circulation models.

The evolution of spatial solitons in the photovoltaic photorefractive crystal can be governed by the specific coupled nonlinear Schrödinger equations. Under the photovoltaic field with the external bias field, the coupled cn–sn-type periodic wave solution and the corresponding photorefractive bright–dark soliton pair were constructed to describe the evolution of beam. The influence of the external bias field on solitonic dynamics is analyzed. In the photovoltaic crystal, coupled sn–cn-type, sn–dn-type periodic wave solutions, solution constructed by products of elliptic functions and the corresponding dark–bright soliton pair and coupled double-peaked soliton solutions are found to describe the evolution of a spatial-phase-modulated photovoltaic soliton and a non-phase-modulated beam.

Oceans play a key role in energy storage in the global Earth–Ocean–Atmosphere system. Within this framework, the knowledge of past evolution and future trends of sea surface temperature is crucial for the future climate scenarios. Previous studies have highlighted the role of sea surface temperature as an important ingredient for the development and/or intensification of heavy precipitation events in the Western Mediterranean basin but have also highlighted its role in heat waves in Europe. In this study, a consistent warming trend has been found for daily sea surface temperature data series derived from satellites (1982–2016) for the whole Mediterranean region and for different temporal scales, from daily to monthly, seasonal and decadal estimates. Additionally, spatial clustering analysis has been run to look for its spatial structure. Two main distribution modes have been found for sea surface temperature in winter and summer, while spring and fall show transitional regimes. Winter mode shows a north-to-south increasing gradient banded structure while summer regime presents a set of well-differentiated areas.

Fast magnetosonic waves are electromagnetic waves with frequencies ranging from a few Hertz to several hundred Hertz, observed primarily near the magnetic equator. Recent studies demonstrate that magnetosonic waves can propagate into the L<2$L< 2$region, while their distributions and propagation properties there remain unclear. Using data from Van Allen Probes, we present the first systematic survey of magnetosonic waves' spatial distribution in the L<2$L< 2$region, revealing important characteristics of their propagation and evolution. The frequency spectra of magnetic power spectral densities reveal that under disturbed geomagnetic conditions, the bandwidth of fast magnetosonic waves shifts to higher frequencies, and the spectra exhibit a radial inner boundary and a low‐frequency boundary, both of which depend on geomagnetic conditions. These findings advance our understanding of the propagation and evolution of magnetosonic waves in the L<2$L< 2$region and their potential role in the inner magnetosphere.

This study explores the spatial variations and physical mechanisms of 10–30-day rainfall anomalies over southeastern China based on daily station-observed rainfall data for the period 1979–2015. Empirical orthogonal function analysis shows that the dominant spatial distribution of 10–30-day rainfall anomalies is a monopole pattern over the south of the middle and lower reaches of the Yangtze River Valley (SMLY). Lead-lag composites reveal that the evolution of such a monopole pattern depends on the coordinated influences of 10–30-day atmospheric intraseasonal oscillations (ISOs) from the tropics and mid-high latitudes. In the upper troposphere, the southeastward-propagating Rossby wave train from the mid-high latitudes, which presents as anomalous anticyclones and cyclones alternating over eastern Europe to southeastern coastal area of China, induces strong ascents (descents) over the SMLY via vorticity advection. Circulation anomalies associated with tropical ISO over East Asia/Western North Pacific trigger a vertical cell with strong updraft (downdraft) over the SMLY and downdraft (updraft) to the south, further enhancing the ascents (descents) over the SMLY, forming the wet (dry) phases of 10–30-day rainfall anomalies. Moreover, due to the meridional non-uniformity of ISO-related diabatic heating along the Indian Ocean longitudes, an anticyclone (cyclone) is generated over the central Indian–northern Bay of Bengal, which tends to anchor the anomalous ascents (descents) over the SMLY through its interaction with the intraseasonal Rossby wave from mid-high latitudes, thus favoring the persistence of wet (dry) phases of the 10–30-day SMLY rainfall anomalies.

The structure of magnetic fields in galaxies remains poorly constrained, despite the importance of magnetism in the evolution of galaxies. Radio synchrotron and far-infrared (FIR) polarization and polarimetric observations are the best methods to measure galactic scale properties of magnetic fields in galaxies beyond the Milky Way. We use synthetic polarimetric observations of a simulated galaxy to identify and quantify the regions, scales, and interstellar medium (ISM) phases probed at FIR and radio wavelengths. Our studied suite of magnetohydrodynamical cosmological zoom-in simulations features high-resolutions (10 pc full-cell size) and multiple magnetization models. Our synthetic observations have a striking resemblance to those of observed galaxies. We find that the total and polarized radio emission extends to approximately double the altitude above the galactic disk (half-intensity disk thickness of h I radio ∼ h PI radio = 0.23 ± 0.03 kpc) relative to the total FIR and polarized emission that are concentrated in the disk midplane (h I FIR ∼ h PI FIR = 0.11 ± 0.01 kpc). Radio emission traces magnetic fields at scales of ≳300 pc, whereas FIR emission probes magnetic fields at the smallest scales of our simulations. These scales are comparable to our spatial resolution and well below the spatial resolution (<300 pc) of existing FIR polarimetric measurements. Finally, we confirm that synchrotron emission traces a combination of the warm neutral and cold neutral gas phases, whereas FIR emission follows the densest gas in the cold neutral phase in the simulation. These results are independent of the ISM magnetic field strength. The complementarity we measure between radio and FIR wavelengths motivates future multiwavelength polarimetric observations to advance our knowledge of extragalactic magnetism.

Microseismic/acoustic emission (MS/AE) location technology is a powerful means to study the spatial evolution characteristics of rock fracture and early warning of geological hazards. This paper investigated the variation in MS/AE location accuracy and the spatial evolution characteristics of granite fracture in complex stress conditions by using the velocity-free MS/AE source location method. Results show that the variation of wave velocity caused by granite fracture is a key factor for the variation of location accuracy. It is expected to improve the location accuracy by dynamically correcting the iterative wave velocity. The evolution process and results of granite microcracks in uniaxial and biaxial stress conditions show consistency and difference. The consistency is that the microcracks start from the edges and corners at both ends of the rock and gradually develop to the central side of the rock. The distribution of AE events changes from scattered to clustered, nucleated, and finally to banded distribution. The difference is that the advance of rock damage strain point and the macroscopic fracture surfaces are mostly perpendicular to the minimum principal stress direction in biaxial stress conditions. This paper is not only a useful supplement to the MS/AE location methods and theories, but also provides a reference for the disaster-causing mechanism of rock instability as well as disaster prevention and control.HighlightsThe variation of wave velocity caused by granite fracture is a key factor for the variation of location accuracy.The microcracks induced by stress in granite fracture start from the edges and corners and gradually develop to the central side of the rock.Stress conditions could significantly affect the damage strain point and the final morphology of cracks in granite.