GRL

In airborne data or model outputs, clouds are often defined using information about Liquid Water Content (LWC). Unfortunately LWC is not enough to retrieve information about the dynamical boundary of the cloud, that is, volume of turbulent air around the cloud. In this work, we propose an algorithmic approach to this problem based on a method used in time series analysis of dynamical systems, namely Recurrence Plot (RP) and Recurrence Quantification Analysis (RQA). We construct RPs using time series of turbulence kinetic energy, vertical velocity and temperature fluctuations as variables important for cloud dynamics. Then, by studying time series of laminarity (LAM), a variable which is calculated using RPs, we distinguish between turbulent and non-turbulent segments along a horizontal flight leg. By selecting a single threshold of this quantity, we are able to reduce the number of subjective variables and their thresholds used in the definition of the dynamical cloud boundary.

The hyporheic zone is a hotspot for biogeochemical cycling where interactions with mineral metals preserve the release and biodegradation of organic matter (OM). A small fraction of OM can still be exchanged between localized sediments and the overlying water column, and recent evidence suggests there exists a longitudinal structuring in sediment dissolved OM (DOM) chemistry across the continental United States (CONUS). In this study, we tested a hypothesis that water extractable sediment DOM chemistry could be explained by sediment metal contents and integrative watershed scale features at the CONUS scale. Crowdsourced samples were characterized for high resolution mass spectrometry and coupled with sediment metals determined via x-ray fluorescence as well as with land cover and soil elemental information obtained from national databases. Our results highlight weak relationships between DOM chemistry and elemental composition at the CONUS scale indicating limited transferability of organo-metal linkages into multi-scale hydrobiogeochemical models.

Jakobshavn Isbræ, a major outlet glacier in Greenland, lost its protective ice shelf in 2002 and has been speeding up and retreating since. We image its grounding line for the first time with a terrestrial radar interferometer deployed in 2016 and detect its migration at tidal frequencies. The southern half of the glacier develops a floating section (3 km × 3 km) that migrates in phase with the tidal difference, up to a distance of 2.8 km, far more than previously expected. We attribute the migration to kilometer-scale seawater intrusions, 10–20 cm in height, with the tide. The intrusions reveal that the glacier bed may be up to 800 m deeper than expected on the south side, which illustrates that our knowledge of bed topography remains limited for this glacier. We expect seawater intrusions to cause rapid melt of basal ice and play a major role in the glacier evolution.

Relic coastal landforms (fossil corals, cemented intertidal deposits, or erosive features carved onto rock coasts) serve as sea-level index points (SLIPs), that are widely used to reconstruct past sea-level changes. Traditional SLIP-based sea-level reconstructions face challenges in capturing continuous sea-level variability and dating erosional SLIPs, such as tidal notches. Here, we propose a novel approach to such challenges. We use a numerical model of cliff erosion embedded within a Monte Carlo simulation to investigate the most likely sea-level scenarios responsible for shaping one of the best-preserved tidal notches of Last Interglacial age in Sardinia, Italy. Results align with Glacial Isostatic Adjustment model predictions, indicating that synchronized or out-of-sync ice-volume shifts in Antarctic and Greenland ice sheets can reproduce the notch morphology, with sea level confidently peaking at 6 m and only under a higher than present erosion regime. This new approach yields insight into sea-level trends during the Last Interglacial.

The high latitude Southern Hemisphere (SH) is an important region for Earth's climate. Ocean heat content, cryosphere interactions, Antarctic bottom water development and the cloud-albedo feedbacks need to be understood to form a complete picture of the climate system. However, the high latitude SH is one of the most under-observed regions due to its remoteness. The advent of satellites and reanalyses have improved our monitoring of this region. Some previous studies observed an increase in precipitation over the SH high latitudes, however we argue that some of the trends in commonly used data sets may be artifacts. We use regression analysis of trends in precipitation and the Southern Annular Mode to contrast these relationships in satellite and reanalysis products, and to evaluate precipitation over the SH. We suggest that sensor changes and the lack of in situ data available for calibration may be responsible for unusual precipitation patterns especially around 65°S.

Cold pools formed by precipitating convective clouds are an important source of mesoscale temperature variability. However, their sub-mesoscale (100 m–10 km) structure has not been quantified, impeding validation of numerical models and understanding of their atmospheric and societal impacts. We assess temperature variability in observed and simulated cold pools using variograms calculated from dense network observations collected during a field experiment and in high-resolution case-study and idealized simulations. The temperature variance in cold pools is enhanced for spatial scales between ∼5 and 15 km compared to pre-cold pool conditions, but the magnitude varies strongly with cold pool evolution and environment. Simulations capture the overall cold pool variogram shape well but underestimate the magnitude of the variability, irrespective of model resolution. Temperature variograms outside of cold pool periods are represented by the range of simulations evaluated here, suggesting that models misrepresent cold pool formation and/or dissipation processes.

Jupiter's plasma sheet has been understood to be primarily composed of Io-genic sulfur and oxygen, along with protons at lower mass density. These ions move radially away from Jupiter, filling its magnetosphere. The material in the plasma sheet interacts with Europa, which is also a source of magnetospheric pickup ions, primarily hydrogen and oxygen. Juno's thermal plasma instrument JADE, the Jovian Auroral Distributions Experiment, has provided comprehensive in situ observations of the composition of Jupiter's plasma sheet ions with its Time-of-Flight mass-spectrometry capabilities. Here, we present observations of the magnetospheric composition in the Europa-Ganymede region of Jupiter's magnetosphere. We find material from Europa is intermittently present at comparable densities to Io-genic plasma. The intermittency of Europa-genic signatures suggests Europa's neutral oxygen toroidal cloud is more localized to Europa's vicinity than its hydrogen cloud. These observations reveal a more complex and compositionally diverse magnetosphere than previously thought.

Mineral preservation and microbial residue production are vital for the accumulation of mineral-associated organic carbon (MAOC) in soils. However, their relative importance and interactive effects remain unclear. Here MAOC content and composition are analyzed in tandem with soil mineral and microbial attributes along a weathering gradient on a volcanic soil sequence. We find that MAOC content increases with increasing mineral weathering states, accompanied by increasing microbial contribution to MAOC. Mineral attributes rather than microbial physiological traits are strongly related to MAOC contents, suggesting that weathering-enhanced mineral preservation capacity overrides microbial residue production in governing MAOC accumulation by increasing reactive minerals. Furthermore, mineral attributes have a strong interactive effect with microbial traits on MAOC accumulation and composition, likely related to increasing fungal abundance in the microbial community with increasing weathering. These findings highlight that mineral weathering may effectively boost persistent SOC in synergy with microbial conversion in the long term.

Hydroxylated isoprenoid GDGTs (OH-GDGTs) have emerged as a novel tool for reconstructing sea surface temperatures. However, when using marine OH-GDGT calibration in lacustrine settings, it leads to a significant overestimation of temperatures, emphasizing the necessity for a thorough examination of OH-GDGTs in lakes. Here, we investigated OH-GDGT distributions in surface sediments from 65 lakes in West China and compiled published Asian lake and global marine OH-GDGT data sets. Among all GDGT-based indices, RI-OH showed the strongest correlation with temperature across Asian lakes. The RI-OH value was higher in lakes than in marine sediments, likely due to differences in the composition of Group 1.1a thaumarchaeotal species between the two settings. The first RI-OH temperature calibration for lakes was developed and it addressed the issue of temperature overestimation when applied to both water column and sediment core, highlighting the potential of OH-GDGTs as a new terrestrial paleothermometer.

A deterministic system of ocean surface waves and flow in the oceanic boundary layer is key to understanding the dynamics of the upper ocean. For the description of such complex systems, a higher-order shear-current modified nonlinear Schrödinger equation is newly derived and then used to physically interpret the interplay between Stokes drift, Eulerian return flow due to a passing wave group, and an open-ocean vertically sheared flow in the extreme sea wave generation. The conditions for the suppression or enhancement of the modulation instability in the rogue wave dynamics in the presence of a background flow are reported, whose relevance and influence to the Craik-Leibovich type 2 instability in triggering a Langmuir-type circulation is discussed. The findings highlight the need for future studies to establish and assess the energy transfer from waves to currents or in the reversing order, asserting a plausible physical mechanism for the dissipation of the surface wave energy through wave-current interactions in the open ocean.

Jeffbenite (Mg3Al2Si3O12) is a tetragonal phase found in so far only in superdeep diamonds, and its thermoelastic parameters are a prerequisite for determining entrapment pressures as it is regarded as a potential indicator for superdeep diamonds. In this study, the thermoelastic properties of synthetic Fe3+-jeffbenite were measured up to 33.7 GPa and 750 K. High-temperature static compression data were fitted, giving (∂K T0/∂ T ) P  = −0.0107 (4) GPa/K and α T  = 3.50 (3) × 10−5 K−1. The thermoelastic properties and phase stability are applied to modeling isomekes, or P-T paths intersecting possible conditions of entrapment in diamond. We calculate that under ideal exhumation, jeffbenite entrapped at mantle transition zone conditions will exhibit a high remnant pressure at 300 K (P inc) of ∼5.0 GPa. Elastic geobarometry on future finds of jeffbenite inclusions can use the new equation of state to estimate entrapment pressures for this phase with still highly uncertain stability field in the mantle.

Understanding the material properties and physical conditions of basal ice is crucial for a comprehensive understanding of Antarctic ice-sheet dynamics. Yet, direct data are sparse and difficult to acquire. Here, we employ ultra-wideband radar to map high-backscatter zones near the glacier bed within East Antarctica's Jutulstraumen drainage basin. Our backscatter analysis reveals that the basal ice in an area of ∼10,000 km2 is composed of along-flow oriented sediment-laden basal ice units connected to the basal substrate, extending up to several hundred meters thick. Three-dimensional thermomechanical modeling supports that these units form via basal freeze-on of subglacial water that originated from further upstream. Our findings suggest that basal freeze-on, and the entrainment and transport of subglacial material play a significant role in an accurate representation of material, physical, and rheological properties of the Antarctic ice sheet's basal ice, ultimately enhancing the accuracy and reliability of ice-sheet modeling.

Ocean mass increase contributes to global sea level rise, and plays an important role in understanding climate change. Here, we develop a data assimilation approach that enables the inference of ocean mass increase from global tide gauge network. This approach incorporates outputs from climate models and sea level fingerprints caused by water mass changes over land areas. The results suggest a trend of 2.15 ± 0.72 mm/yr for ocean mass increase over the period 1993–2022, which closes the global sea level budget with estimates of thermosteric sea level rise. Furthermore, the inferred ocean mass increase offers an insight into the causes of sea level rise since 1950. These findings emphasize the significance of climate models, in addition to simulating sea level changes, they contribute to understanding causes of sea level rise over the past decades.

Recent extremely heavy precipitation has led to substantial economic losses and affected millions of residences in the Lancang-Mekong River Basin (LMRB). This study analyzed the spatial-temporal characteristics of the annual maximum precipitation (R1X) of the LMRB and identified the moisture sources and pathways conducive to R1Xs using a Lagrangian back trajectory model. Results show that India Ocean and Bay of Bengal (IO/BOB), local evapotranspiration, and West Pacific Ocean and East China (WP/EC) are the three main moisture transport pathways of the R1Xs in LMRB, contributing 68.3%, 20.4% and 11.3% of the trajectories, respectively. R1Xs in the downstream eastern area are affected by tropical cyclones bringing large amounts of moisture from the WP/EC. As tropical cyclones shifted northward under climate change impact, more extreme precipitation occurred over the LMRB due to moisture coming from WP/EC, but those from the IO/BOB had decreased because of the slowdown of flows across the Equator.

Mars features a crustal dichotomy, with its southern hemisphere covered by a thicker basaltic crust than its northern hemisphere. Additionally, the planet displays geologically recent volcanism only in its low latitude regions. Previous giant impact models coupled with simulations of mantle convection have shown that the crustal dichotomy can be explained by post-impact melt crystallization that emplaced a thick crust in the southern hemisphere. In this study, we show that the depleted residue left behind by the original post-impact crustal formation can spread laterally, potentially persisting beneath the northern hemisphere to the present-day. Such a large-scale mantle province would concurrently explain both the prevalence of long-term magmatism on Mars and its strong preference for localized equatorial regions.

In the Baltic Sea, sea level variations are often very pronounced. During the winter season, storm surges caused by strong extratropical cyclones (ETCs) can have major societal impacts on coastal cities. In this study, using reanalysis-based cyclone tracks and in-situ tide gauge records, we show that serial cyclone clustering (SCC) leads to higher sea levels in the Baltic Sea than situations where only one ETC passes the tide gauge. Consequently, almost half of extreme sea level events in the Baltic Sea are associated with cyclone clustering periods. For example, in Helsinki, 45% of the extreme sea level events coincided with SCC periods of three or more ETCs, while only 6% of the events coincided with a single ETC. Our study represents a significant advance in the understanding of the factors influencing sea level variations in the Baltic Sea.

When the solar wind speed falls below the local Alfvén speed, the magnetotail transforms into an Alfvén wing configuration. A Grid Agnostic Magnetohydrodynamics for Extended Research Applications (GAMERA) simulation of Earth's magnetosphere using solar wind parameters from the 24 April 2023 sub-Alfvénic interval is examined to reveal modifications of Dungey-type magnetotail reconnection during sustained sub-Alfvénic solar wind. The simulation shows new magnetospheric flux is generated via reconnection between polar cap field lines from the northern and southern hemisphere, similar to Dungey-type magnetotail reconnection between lobe field lines mapping to opposite hemispheres. The key feature setting the Alfvén wing reconnection apart from the typical Dungey-type is that the majority of new magnetospheric flux is added to the polar cap at local times 1–3 (21-23) in the northern (southern) hemisphere. During most of the sub-Alfvénic interval, reconnection mapping to midnight in the polar cap generates relatively little new magnetospheric flux.

The variability of Mars exosphere over monthly to solar-cycle scales at 251 and 412 km altitude is quantified by analysis of 41-Ls mean densities derived from precise orbit determination of the Mars Reconnaissance Orbiter (MRO) and Mars Odyssey (MO) satellites, respectively. The data encompass 2006–2020 (MRO) and 2002–2020 (MO). At both altitudes, most of the variance is captured by cos(Ls–ϕ), where ϕ ≈ 258°. This term represents the effects of solar heating changes due to the eccentricity of Mars orbit around the Sun, and climatological changes in heating due to lower-atmosphere dust loading, which does not play a significant role. The remaining variability is connected with the “irregular” variability of solar flux over monthly time scales. For MO, the presence of Helium disrupts a clean correlation with these sources.

This study unravels the characteristics, mechanisms, and predictability of four consecutive record-breaking heatwaves hitting North China in June and July 2023. The first three heatwaves primarily influenced the northern part of North China and were accompanied by consistent anticyclonic anomalies in the upper troposphere. The anomalous anticyclone was caused by the British–Baikal corridor teleconnection along the polar front jet, particularly during the second heatwave. In contrast, the fourth heatwave was induced by a distinct low-pressure system, attributed to the Silk Road pattern along the subtropical jet. The presence of this low-pressure system and its interaction with atmospheric rivers and local topography led to the foehn wind, further contributing to the rise in surface temperatures. Sub-seasonal to seasonal models can effectively predict the occurrence of all heatwaves 2–5 days in advance despite underestimating the intensity. However, models exhibit limitations in providing reliable predictions when the lead time exceeds 2 weeks.

The impact of assimilating ground-based radar reflectivity on the rainband structure and secondary eyewall formation (SEF) of Hurricane Matthew (2016) is investigated within the framework of the Hurricane Weather Research and Forecasting model and its hybrid three-dimensional ensemble-variational data assimilation (DA) system. Compared to the control experiment (no radar reflectivity DA), the radar reflectivity DA experiment shows a clear signal of concentric eyewall and eyewall replacement cycle. Results demonstrate that radar reflectivity DA improves the stratiform rainband analysis, resulting in the mid-level cooling associated with mesoscale descending inflow (MDI). The MDI further contributes to the low-level acceleration maximum with boundary layer dynamics and triggers new convective updrafts in the SEF region. Momentum budget analysis also suggests that the mean vertical advection of absolute angular momentum plays an important role in the local momentum tendency in the SEF region in Hurricane Matthew (2016).