GRL

An obvious long-term drying trend in recent early springs (February–March–April) is observed over southeastern China (SEC). Here, we attribute this drying to the weakened subtropical westerlies and deflected by the Tibetan Plateau (TP). Climatologically, the low-level southwesterlies at the southeastern margin of the TP, a branch of the upstream subtropical westerly jet deflected by the TP terrain, bring water vapor to SEC and the southerlies move upward over SEC mainly through isentropic gliding mechanism, inducing persistent precipitation in early spring. However, the subtropical westerlies weakened significantly in recent decades due potentially to the decreased Eurasian snow cover. Consequently, an easterly trend appears along the southern margin of the TP with anomalous northeasterlies over SEC. These northeasterlies suppress both moisture supply and upward motions over SEC, and reduce regional early spring precipitation. Our results highlight the interaction between the TP terrain and the weakened subtropical westerlies that leads to the drying SEC.

Based on observations from the Magnetospheric Multiscale mission, this study presents an analysis of a short large-amplitude magnetic structures (SLAMS) event with simultaneous occurrence of low- and high-frequency magnetosonic whistler waves. It was found that low-frequency magnetosonic whistler waves around the lower-hybrid frequency emerge in the presence of solar wind ions and local low-energy ions in the trailing region of SLAMS. Additionally, counter-propagating whistler waves (the high-frequency branch of the magnetosonic whistler wave) are observed within SLAMS, coinciding with a perpendicular temperature anisotropy in the electron population. Instability analyses demonstrate that these low-frequency waves are induced by the two-stream instability associated with the cross-field relative velocity between low-energy ions and electrons, while whistler waves are locally generated by the whistler anisotropy instability. Our results shed light on the impact of SLAMS on particle and wave dynamics in the terrestrial foreshock.

After days of intense solar activity, active region AR3664 launched seven CMEs toward Earth producing an extreme G5 geomagnetic storm commencing at 17:05 UT on 10 May 2024. The storm impacted power grids, disrupted precision navigational systems used by farming equipment, and generated aurora seen around the globe. The storm produced remarkable effects on composition, temperature, and dynamics in the Earth's thermosphere that were observed by NASA's Global-scale Observations of the Limb and Disk (GOLD) mission and are reported here for the first time. We use synoptic disk images of ΣO/N2 and neutral temperature (at ∼160 km) measured by GOLD to directly link dynamics resulting from the storm with dramatic changes in thermospheric composition and temperature. We observe a heretofore unseen spatial morphology simultaneously in ΣO/N2, neutral temperature, and total electron content. Equator-to-pole temperature differences reach 400 K with high latitude peak neutral temperatures near 160 km exceeding 1400 K.

Colorado River streamflow has decreased 19% since 2000. Spring (March-April-May) weather strongly influences Upper Colorado River streamflow because it controls not only water input but also when snow melts and how much energy is available for evaporation when soils are wettest. Since 2000, spring precipitation decreased by 14% on average across 26 unregulated headwater basins, but this decrease did not fully account for the reduced streamflow. In drier springs, increases in energy from reduced cloud cover, and lowered surface albedo from earlier snow disappearance, coincided with potential evapotranspiration (PET) increases of up to 10%. Combining spring precipitation decreases with PET increases accounted for 67% of the variance in post-2000 streamflow deficits. Streamflow deficits were most substantial in lower elevation basins (<2,950 m), where snowmelt occurred earliest, and precipitation declines were largest. Refining seasonal spring precipitation forecasts is imperative for future water availability predictions in this snow-dominated water resource region.

We show that the winter Beaufort High (BH) index defined by sea level pressure (SLP) has a robust negative trend under the scenarios SSP5-8.5 and SSP2-4.5, with a reduction by about 5 hPa and 2 hPa, respectively, by the end of the 21st century. The negative trends in the BH SLP are associated with the changes in the background SLP over the Arctic basin. However, the vorticity of the winter BH tends to intensify under SSP5-8.5, but shows no robust increase under SSP2-4.5. The intensification is associated with the enhanced ridge over the Western Arctic. Therefore, it is necessary to take into account the dynamic aspects of the BH, such as vorticity. Based on this assessment, under the most likely emissions scenario, the winter BH is likely to weaken through the 21st century, in terms of SLP, but shows no robust changes in term of vorticity.

We present an innovative approach that combines a unique real-time data set documenting absolute dissolution rates of a calcite crystal with an original reactive transport model tailored to the analysis of the dynamics of nano-scale mineral dissolution processes. Providing robust and physically based fundamental understanding on the kinetics of mineral dissolution is at the core of various geo-engineered strategies to quantify chemical weathering patterns across diverse spatial and temporal scales. Here, we rely on data obtained through Atomic Force Microscopy. We provide a mathematical framework to describe three-dimensional dynamics of the mineral surface topography, and show convergence of the numerical approach for vertical grid spacing down to sub-nm resolution.

The Great Lakes Region (GLR) of North America is at the intersection of multiple extratropical cyclone (ETC) tracks, and the region's cold-season climate is heavily influenced by the large temperature gradients and intense precipitation associated with these cyclones. The goal of this study is to understand how ETCs are changing within a warming climate. Historical GLR cyclone characteristics from 1959 to 2021 are examined using a storm tracking algorithm and the ERA-5 atmospheric reanalysis. Of the 886 cyclones identified, half are the large long-track cyclones that are typically included in ETC studies, and half are smaller short-track cyclones that, while not always considered in ETC studies, still have an important impact on the GLR with significant precipitation trends. While all cyclones exhibit strong interannual variability, storm trajectories appear to be migrating northward and, most notably, the cyclones are becoming warmer and wetter at a rate faster than the background climate.

It has been difficult to establish trends in the observed jet streams, despite modeling studies suggesting they will move polewards in a warming world. While this is partly due to biases between the models and observations, we propose that another uncertainty is rooted in the choice of statistic used to determine the ‘jet latitude’ — one measure used to quantify the jet position. We use seven different jet latitude statistics, four climate reanalysis products, and CMIP6 simulations to assess the relative importance of different uncertainties associated with lower-tropospheric North Pacific Jet (NPJ) trends. Our results show a statistically significant poleward trend in the observed winter NPJ across all reanalyzes and using all jet latitude statistics. The magnitude of this trend is most sensitive to the choice of statistic. Furthermore, we find that the NPJ shifts poleward in Autumn under high emission scenarios, which is robust to the choice of jet statistic.

Ecosystem-scale photosynthetic efficiency (EPE) is proposed as an effective indicator to quantify gross primary productivity (GPP), but how the coupling between EPE and GPP varies as vegetation resilience decreases has not been evaluated. Here, we quantified forest resilience with optimized Bayesian models. With the use of multisource satellite and modeling data, our study revealed that forests on the Loess Plateau and in the Qinba Mountains in China are experiencing rapid resilience loss and are already facing mortality warnings after 2010. Reductions in resilience also drove the marked decoupling of GPP from EPE. Notably, the decline in resilience was accompanied by a decrease in EPE in about 74% of the forests while GPP increased. The mechanism underlying this decoupling could be attributed to enhanced atmospheric water demand and soil water constraints. The dynamic relationships found here could help to improve forest mortality models and enhance photosynthesis-based GPP evaluation.

A crucial factor influencing the mass balance of the West Antarctic Ice Sheet is the Amundsen Sea Low (ASL), a climatological low-pressure region situated off the West Antarctic coast. However, albeit the deepening of the ASL since the 1950s has been attributed to anthropogenic forcing, the multi-decadal variability of the ASL remains poorly understood, because of a lack of long observations. Here, we apply a newly developed data assimilation method to reconstruct the ASL over 1870–2000. We study the forced and internal variability of the ASL using our new reconstruction in concert with existing large ensembles of climate model simulations. Our findings robustly demonstrate that an atmospheric teleconnection originating from the tropical Indo-Pacific is the main driver of ASL variability at the multi-decadal time scale, with resemblance to the Interdecadal Pacific Oscillation. Since the mid-20th century, anthropogenic forcing has emerged as a dominant contributor to the strengthening of the ASL.

Current global historical reanalyzes prevent to adequately examine the role of the near-core surface wind structural properties on tropical cyclones climate trends. Here we provide theoretical and observational evidences that they are crucial for the monitoring of integrated kinetic energy. The kinetic energy balance is reduced to a simple rule involving two parameters characterizing the surface wind structure and directly suggested by the governing equations. The theory is uniquely verified with a database of high-resolution ocean surface winds estimated from all-weather spaceborne synthetic aperture radar. Such measurements provide indirect estimates of a multiplicative constant modulating the kinetic energy balance and associated with the system thermodynamics. Consequently, accumulated high-resolution acquisitions of the ocean surface shall allow to better monitor the integrated kinetic energy and provide new means to tackle climatological studies of tropical cyclones destructiveness.

Altitude-triggered lightning provides favorable conditions for the research of bidirectional leader system. In the summer of 2023, altitude-triggered lightning experiment was conducted on the Field Experiment Base on Lightning Sciences, China Meteorological Administration. The multifrequency radiation characteristics of bidirectional leaders and the interactions of both ends during the propagation are analyzed. Specifically, the discharge processes that produce LF-MF magnetic radiations from bidirectional leaders are revealed by high-speed images, and these LF-MF radiations correspond to the VHF radiations generated by bidirectional leaders well. Unlike the strong correlation between LF-MF radiation strengths and discharge intensities, the VHF radiation strengths exhibit significant variation even among similar-intensity discharge events, as VHF radiations correspond to the random and microscopic discharge processes associated with streamers. Furthermore, the changes in leader speed and channel brightness before and after the initiation of bidirectional leaders indicate that the development of the two ends of bidirectional leaders is mutually reinforcing.

Satellite imagery provides a global perspective for studying river hydrology and water quality, but clouds remain a fundamental limitation of optical sensors. Explicit studies of this problem were limited to specific locations or regions. In this study, we characterize the global severity of this limitation by analyzing 22 years of daily satellite cloud cover data and modeled river discharge for a global sample 21,642 river reaches of diverse sizes and climates. Our results show that the bias in observed river discharge is highly organized in space, particularly affecting Tropical and Arctic rivers. Given the fundamental nature of this cloud limitation, optical satellites will always provide a biased representation of river conditions. We discuss several strategies to mitigate bias, including modeling, data fusion, and temporal averaging, yet these methods introduce their own challenges and uncertainties.

Marine-terminating glacier fjords play a central role in the transport of oceanic heat toward ice sheets, regulating their melt. Mixing processes near glacial termini are key to this circulation but remain poorly understood. We present new summer measurements of circulation and mixing near a marine-terminating glacier with active sub-glacial discharge. 65% of the fjord's vertical overturning circulation is driven by the buoyant plume, however we newly report intense vertical and horizontal mixing in the plume's horizontal spreading phase, accounting for the remaining 35%. Buoyant plume theory supports 2%–5% of total glacial melt. Thus, most of the heat associated with vertical overturing short-circuits the glacial front. We find however that turbulence in the horizontal spreading phase redistributes the short-circuited heat back into the surface waters of the near-glacial zone. Our findings highlight the need for further research on the complex mixing processes that occur near the glacier terminus.

We report an Arase-all sky imager (ASI) conjugate event in which the pulsating aurora (PsA) has a one-to-one correspondence with chorus bursts. Wavelet analysis displayed three peaks at ∼0.3 Hz, 4 Hz, and >10 Hz, corresponding to the main pulsation, internal modulation, and fast modulation, respectively. These correspond to the old terms of ∼5–15 s pulsations, chorus risers/elements and subelements/subpackets, respectively. Electron “microbursts” correspond to the 4-Hz peak. The internal and fast modulations are further verified by the analysis based on fast Fourier transform analyses. Moreover, the spatial distributions of the Fourier spectral amplitude show that the internal and fast modulations are well-structured within auroral patches. The above results indicate a paradigm shift away from quasilinear theory which implicitly assumes diffuse wave generation. The three time-scale modulations are consistent with coherent chorus which has been theoretically argued to lead to pitch angle transport three orders of magnitude faster.

Compressional and shear wave velocities of polycrystalline stishovite (SiO2) have been measured at simultaneous high pressures and temperatures up to 14.5 GPa and 800°C. By fitting velocities to the finite strain equations, the elastic moduli and density were determined to be K S0 = 306.6(46) GPa, K S′ = 4.92(10), ∂K S /∂T = −0.024(1) GPa/K, G 0  = 229.0(34) GPa, G′ = 1.07(10), ∂G/∂T = −0.017(1) GPa/K, ρ 0  = 4.287(2) g/cm3. Our modeling suggested that, in the eclogite, coesite-stishovite transition can increase P and S wave velocities by 2.4% and 3.5%, respectively. A comparison between geophysical observations and our model shows that the coesite-stishovite phase transition in the eclogite can potentially be responsible for the occurrence of the X discontinuity beneath Hawaii. In addition, our current results suggest an eclogite-rich layer between 340 and 450 km depth beneath Hawaii. The eclogite concentration at the top and bottom of the layer is 41–55 vol% and >77 vol%, respectively.

Carbon storage technology is primarily targeted in saline formations, which is a porous rock matrix filled with brine, sealed with a low permeability caprock. There are significant variations of CO2 wetting properties, typically reported in the literature as contact angle of CO2 and brine interacting with a rock material, suggesting that CO2 could become wetting under geostorage conditions and negatively impact containment effectiveness. Here, we performed the first controlled laboratory measurements of CO2-brine contact angles on shale rocks from low permeability sealing formations with distinctive mineralogic properties—calcite-rich, quartz-rich, and dolomite-rich. We targeted temperatures at 40° and 100°C, pressures at 8.3, 34.5, and 62.1 MPa, and salinity at 35,000 and 260,000 ppm. Results show no significant change in contact angle with mineralogy, temperature, pressure, salinity, and CO2 bubble size. We conclude that caprocks will remain water-wet at geologic CO2 storage conditions and will not lose their capillary sealing capacity.

Delamination of lower continental lithosphere is known to have occurred under different tectonic settings. However, its fate in the mantle is poorly understood. By analyzing global seismic models, we find that most of likely lithosphere that delaminated during the Cenozoic and Mesozoic is preserved in the mantle transition zone, especially beneath North America and Africa. Numerical experiments indicates that delaminated lithosphere can remain stagnant in the mantle transition zone for tens of millions of years, followed by its potential sinking into the lower mantle or re-rising to shallower depths depending on its density, the Clapeyron slope of the spinel-to-post-spinel phase change and increase in mantle viscosity at ∼660–1,000 km depths. Re-ascent occurs when delaminated lithosphere is reheated so that its effective density becomes lower than its surrounding ambient mantle after ∼100 Myr. Delaminated fragments can also potentially be mobilized by underlying global mantle flow to move horizontally away from plume regions.

Two major earthquakes of Mw7.8 and Mw7.5 ruptured the Southern East Anatolian Fault (SEAF) and the Savrun-Çardak-Sürgü fault (SCSF), devastating southeast Türkiye and northwest Syria on 6 February 2023. We adopt innovative nonlinear and linear approaches to analyze the coseismic ground displacements and estimate the complex slip geometry. Unlike conventional analytical solutions that simplify crust heterogeneity, finite-element fault models invert the displacement data and simulate the dual-fault geometry with non-uniformly distributed shallow crustal materials. Our results suggest the west-dipping SEAF and north-dipping SCSF accommodate earthquake slips of >10 m. Their respective slip distributions and proximal aftershocks correlate spatially with local seismic velocity anomalies (i.e., ΔVp and ΔVs), which implies differences in structural control along these two faults and provides insights into assessing the seismic hazard of mixed incipient-mature fault systems.

Monitoring the generation and movement of equatorial plasma bubbles (EPBs) in a large longitude region is crucial important for better understanding their day-to-day variability. Using the newly developed Low lAtitude long Range Ionospheric raDar (LARID) at Dongfang (19.2°N, 108.8°E, dip lat. 13.8°N), China, an extremely long-range experiment for observing EPB irregularities in a range of ±9,600 km to the radar site was first carried out. The results show that EPB irregularities with ranges up to 7,000 and 9,500 km were observed by the east and west beams of LARID, respectively. By incorporating simultaneous observations from GNSS receiver and ionosonde networks, it is demonstrated that the EPBs generated from post-sunset to sunrise over a very wide longitude of ∼140°, from Pacific to Africa could be observed by LARID. The results, for the first time, demonstrate the possibility for tracing global EPBs in real time using a few low latitude over-the-horizon radars.