• Issue
    Volume 49, Issue 23
    16 December 2022

Research Letter

Space Sciences

Free Access

Updated Spherical Harmonic Magnetic Field Moments of Ganymede From the Juno Flyby

  • First Published: 12 December 2022
Key Points

  • Using data from Juno's orbit 34 flyby of Ganymede, we present updated spherical harmonic moments of the moon's internal magnetic field

  • Ganymede's dipole moment is very dominant, with quadrupole moments that are over a factor of 10 weaker than the main dipole term

  • We find a quadrupole fit to be unjustified, strengthening previous arguments that deviations from a dipole are due to induction signatures

Planets

Open Access

Juno Plasma Wave Observations at Ganymede

  • First Published: 13 May 2022
Key Points

  • Whistler-modes, electron cyclotron harmonics, upper hybrid band and radio emissions are detected in and near Ganymede's magnetosphere

  • Three distinct regions in and near the magnetosphere are observed, wake, nightside, and dayside

  • The dayside ionosphere exhibits higher and more variable electron densities than does the nightside

Space Sciences

Open Access

Energetic Charged Particle Fluxes Relevant to Ganymede's Polar Region

  • First Published: 13 May 2022
Key Points

  • We present energy spectra from energetic charged particle data from Juno's close flyby of Ganymede in 2021

  • We find a drop in electron fluxes on polar field lines compared to the surrounding region whereas ion fluxes are similar in both regions

  • We compute sputtering rates to evaluate particle weathering, as a step toward understanding the distribution of Ganymede's surface ice

Planets

Open Access

Juno's Close Encounter With Ganymede—An Overview

  • First Published: 12 December 2022
Key Points

  • Juno passed Ganymede on 7 June 2021 at an altitude of approximately 1,000 km, the closest any spacecraft has come since the Galileo mission ended in 2003

  • The path of Juno's trajectory allowed the spacecraft to pierce Ganymede's unique magnetosphere and map a swath of its surface and subsurface

  • The geometry of the flyby is described for the close pass in June and a more distant pass (approximately 50,000 km) on 20 July 2021

Free Access

Ganymede's Ionosphere Observed by a Dual-Frequency Radio Occultation With Juno

  • First Published: 10 May 2022
Key Points

  • A dual-frequency radio occultation experiment of Ganymede's ionosphere was conducted with the Juno spacecraft on 7 June 2021

  • Ingress observed an ionosphere with peak density 2,000 ± 500 (1-σ) cm−3 but no statistically significant signature was detected on egress

  • Ingress detection occurred in the open field line region, where higher electron impact ionization rates may increase the electron density

Issue Information

Free Access

Issue Information

  • First Published: 29 November 2022

Research Letter

Space Sciences

Free Access

Energetic Charged Particle Observations During Juno's Close Flyby of Ganymede

  • First Published: 12 December 2022
Key Points

  • Energetic particle measurements reveal new insights into Ganymede's magnetosphere for the only close Juno flyby

  • Electron pitch angle distributions reveal distinct regions of Ganymede's magnetosphere

  • Evidence for energetic electron precipitation onto Ganymede's surface within the open field line region

Cryosphere

Open Access

Uncertainty in Reconstructing Paleo-Elevation of the Antarctic Ice Sheet From Temperature-Sensitive Ice Core Records

  • First Published: 23 November 2022
Key Points

  • A widely-used, temperature-based paleoaltimetry method is derived from the first law of thermodynamics

  • Estimates of relative elevation change between Antarctic ice core sites yield large uncertainties and low signal-to-noise ratios

  • Uncertainty arises from spatial variability in the diabatic temperature change, which is influenced by elevation-induced circulation changes

Climate

Open Access

Intrinsic Century-Scale Variability in Tropical Pacific Sea Surface Temperatures and Their Influence on Western US Hydroclimate

  • First Published: 28 November 2022
Key Points

  • A linear inverse model is used to quantify the natural variability in the El Niño/Southern Oscillation-southwest United States (ENSO-SWUS) teleconnection, and it suggests considerable intrinsic variability

  • This natural variability demonstrates that detecting anthropogenic changes in the ENSO-SWUS hydroclimate teleconnection will be difficult

  • CMIP6 shows an improvement in modeling the ENSO-SWUS teleconnection, but uncertainty remains in the projected future climate

Atmospheric Science

Open Access

Pathways of Influence Between Northern Hemisphere Blocking and Stratospheric Polar Vortex Variability

  • First Published: 16 November 2022
Key Points

  • The pathways of influence between European and west Pacific blocking and polar vortex variability are quantified using causal inference

  • Both upper tropospheric and lower stratospheric wave-activity fluxes mediate these pathways, and both are needed for a full description

  • Our results suggest additional causal factors play a role in how blocking affects polar vortex variability and sudden stratospheric warmings

Open Access

The Relationship Between Reflectivity and Rainfall Rate From Rain Size Distributions Observed in Hurricanes

  • First Published: 07 November 2022
Key Points

  • The scatter in reflectivity (Z) -rainfall rate (R) distribution increases up to 48 dBZ or 25 mm hr−1, after which it decreases rapidly

  • There are significant uncertainties associated with using a power law Z-R relationship to estimate rainfall rate from radar reflectivity

  • The result from a machine learning model shows that rainfall estimation is improved if drop size information and reflectivity are both used

Space Sciences

Open Access

Successive Westward Traveling Surges Driven by Sequential Plasma-Sheet Bubble Injections

  • First Published: 23 November 2022
Key Points

  • Five westward traveling surges (WTSs) correspond well with successive dipolarizations and fast plasma flows in the magnetosphere from observations

  • Rice Convection Model confirms that continual plasma-sheet bubble injections can lead to the sequential westward traveling surges

  • The expansion speeds of WTSs are linearly proportional to the increase of Bz in the magnetosphere

Solid Earth

Open Access

Electric Discharge in Erupting Mud

  • First Published: 12 December 2022
Key Points

  • Laboratory experiments show that jets of erupting mud can create electric discharge

  • Decreasing the proportion of fine particles and increasing water content suppress number and magnitude of electric discharge events

  • Electric discharge is one mechanism that may enable self-ignition of hydrocarbons during explosive mud volcano eruptions

Climate

Open Access

Anthropogenic Contributions to the 2021 Pacific Northwest Heatwave

  • First Published: 16 November 2022
Key Points

  • The Pacific Northwest (PNW) heatwave was unprecedented in the observational record over a large area

  • Statistical and global climate models fail to inform about human influence on the PNW heatwave, as it is a far outlier

  • Hindcast attribution methods can provide limited and conditional information about the human influence on the PNW heatwave

Atmospheric Science

Open Access

Impact of Higher Spatial Resolution on Precipitation Properties Over Australia

  • First Published: 05 December 2022
Key Points

  • Increasing the horizontal resolution alone did not help address problems with simulating regional precipitation in this case study

  • Significant model developments are required to reap the benefits of high horizontal resolution

Planets

Free Access

UVS Observations of Ganymede's Aurora During Juno Orbits 34 and 35

  • First Published: 12 December 2022
Key Points

  • The high spatial resolution observations revealed auroral emissions of over 1000 Rayleighs, brighter than previously observed
  • The leading hemisphere aurora exhibits an intense auroral curtain with a sharp poleward boundary and more slowly tapering equatorial edge

  • Juno-UVS observed Ganymede's auroral emissions extending up to a maximum of 50 km altitude

Solid Earth

Open Access

Violent Groundwater Eruption Triggered by a Distant Earthquake

  • First Published: 23 November 2022
Key Points

  • We document groundwater eruption 3,200 km away from the 2004 magnitude 9.1 Sumatra earthquake

  • Tidal analysis of groundwater level shows that permeability increased

  • Eruption triggered by an increased crustal permeability and runaway CO2 exsolution

Climate

Open Access

A Modeling Perspective on the Lingering Glacial Sea Surface Temperature Conundrum

  • First Published: 12 December 2022
Key Points

  • Last Glacial Maximum (LGM) experiments indicate that both warmer and colder sea surface temperature (SSTs) are inconsistent with glacial land surface temperature (LST) reconstructions

  • A higher reconstruction data coverage is needed for low-elevation locations, particularly in South America and Australia

  • Evaluation of climate models is still a challenge by using reconstructed LST and SST for the LGM

Open Access

Abrupt Drying on the Southeast Coast of China During the Mid-to-Late Holocene Transition

  • First Published: 28 November 2022
Key Points

  • Increasing aridity on the southeast coast of China from 4.7 to 3.8 ka captured by the hydrogen isotope compositions (δD) of leaf waxes

  • The abrupt drying is mainly shaped by a more El Niño-like state over the tropical Pacific Ocean during the mid-to-late Holocene transition

  • Such a shift in hydroclimate might have promoted the development of mixed rice and millet farming on the southeast coast of China

Hydrology and Land Surface Studies

Open Access

Global Recharge Data Set Indicates Strengthened Groundwater Connection to Surface Fluxes

  • First Published: 29 November 2022
Key Points

  • A global recharge data set indicates that climate strongly shapes the fraction of precipitation that will recharge groundwaters

  • This recharge data set indicates more recharge globally than existing global hydrological models suggest

  • Thus, more groundwater must contribute to evaporation and streamflow than represented by current global models and water cycle diagrams

Solid Earth

Open Access

Joint Geodynamic-Geophysical Inversion Suggests Passive Subduction and Accretion of the Ontong Java Plateau

  • First Published: 01 December 2022
Key Points

  • The joint geodynamic-geophysical inversion approach can help distinguish ambiguous dynamic behaviors of oceanic plateau subduction

  • The Bouguer gravity and other observations of Ontong Java Plateau (OJP) favor the passive collision model over the active collision model

  • OJP should have played a passive role in the collision process, implying the overestimation in previous studies

Oceans

Open Access

Assessing Predictability of Marine Heatwaves With Random Forests

  • First Published: 23 November 2022
Key Points

  • Marine heatwaves in the northeast Pacific are predictable on weekly lead times using atmospheric and oceanic conditions

  • Average accuracy at predicting marine heatwave presence/absence is 76%, but lowers to 38% when forecasting their severity

  • Machine learning approaches should be considered to augment our ability to forecast marine heatwaves

Space Sciences

Free Access

Juno Magnetometer Observations at Ganymede: Comparisons With a Global Hybrid Simulation and Indications of Magnetopause Reconnection

  • First Published: 12 December 2022
Key Points

  • LATMOS hybrid numerical simulation provides a global description of Ganymede's magnetosphere in the context of Juno's flyby

  • We find the upstream magnetopause location and orientation based on Juno Magnetometer data are consistent with previous Galileo observations

  • The non-zero magnetic field normal component across the magnetopause and detection of flux ropes are indicators of magnetic reconnection

Climate

Open Access

Southward Migration of Arctic Ocean Species During the Last Glacial Period

  • First Published: 14 November 2022
Key Points

  • Arctic ostracods inhabited the Yellow Sea between 120 and 100 ka (Marine Isotope Stage [MIS] 5d stadial) and 30–15 ka (MIS 3–2, peak Last Glacial)

  • The presence of Arctic ostracods indicates the enhancement of Yellow Sea Bottom Cold Water formation

  • The East Asian winter monsoon controlled the southward and northward migrations of Arctic marine species

Solid Earth

Open Access

Yield Estimation of the August 2020 Beirut Explosion by Using Physics-Based Propagation Simulations of Regional Infrasound

  • First Published: 23 November 2022
Key Points

  • Explosion yield of the 2020 Beirut explosion is estimated based on infrasound waveforms

  • Full 3-D physics-based numerical simulations are performed to predict infrasound waveform and energy attenuation in atmospheric propagation

  • Joint seismoacoustic analysis is explored to improve the explosion yield and depth constraint

Open Access

Localized Origin at the Core-Mantle Boundary of the 1969 Geomagnetic Impulse

  • First Published: 23 November 2022
Key Points

  • The 1969 impulse originated under central and North America as a north-south oriented localized dipole of field acceleration change

  • It was proceeded by a localized surge in secular variation and field acceleration patterns moved poleward during the event

  • We suggest it was caused by a burst of vigorous convection close to the core surface which triggered flux expulsion and hydromagnetic waves

Oceans

Open Access

What Can Hydrography Between the New England Slope, Bermuda and Africa Tell us About the Strength of the AMOC Over the Last 90 years?

  • First Published: 23 November 2022
Key Points

  • Direct measurements along the Oleander line (∼37°N) show that the depth of the Atlantic Meridional Overturning Circulation (AMOC) maximum is close to 1,000 m

  • Net northward transport between North America and Bermuda equals 41.1 ± 0.4 Sv of which the AMOC accounts for about 18.4 ± 0.6 Sv

  • Net northward transport NW of Bermuda slowed by 2 ± 0.8 Sv between 1930 and 2020 with 0.4 ± 0.6 Sv attributed to an AMOC decline

Solid Earth

Open Access

Characterize Basin-Scale Subsurface Using Rocket-Triggered Lightning

  • First Published: 02 December 2022
Key Points

  • An efficient 3-D forward and inverse model based on the temporal moment is developed to solve Maxwell’s equations in random parameter fields

  • Triggered lightning tomography yields an excellent subsurface electric conductivity spatial distribution in a basin of several kilometers

  • Deep lightning rods in the subsurface improve vertical resolution and depth of investigation

Open Access

Self-Similarity of Seismic Moment Release to Volume Change Scaling for Volcanoes: A Comparison With Injection-Induced Seismicity

  • First Published: 16 November 2022
Key Points

  • We observe a similar moment-volume scaling for volcano seismicity, contrasting with the range exhibited by injection-induced examples

  • The results show that scaling between moment release and volume change can be used to estimate intruded volumes

  • This also provides insights into the geologic factors which control the crust's response to volume changes

Atmospheric Science

Open Access

Effects of Stratospheric Gravity Waves on Convection in the Troposphere During Typhoon Lekima 2019

  • First Published: 09 December 2022
Key Points

  • The stratospheric gravity waves (SGWs) with downward propagating phase can reach down into the troposphere

  • Downward-propagating gravity waves promote the release of convective instability energy in the upper troposphere

  • The intensity of SGWs can be used as a proxy for the intensity of the convection

Hydrology and Land Surface Studies

Open Access

A New Simulation-Optimization Framework for Estimation of Submarine Groundwater Discharge Based on Hydrodynamic Modeling and Isotopic Data

  • First Published: 12 December 2022
Key Points

  • A new simulation-optimization framework is developed for submarine groundwater discharge (SGD) study using hydrodynamic modeling and isotopic data

  • The new framework accounts for spatial variation of SGD, not considered in traditional mass balance modeling

  • Seawater isotope sampling should be carefully planned and conducted to reduce uncertainties of SGD estimation

Oceans

Open Access

A Deep Learning-Based Bias Correction Method for Predicting Ocean Surface Waves in the Northwest Pacific Ocean

  • First Published: 05 December 2022
Key Points

  • We provide a predicting scheme for significant wave height by combining a numerical wave model and a deep learning model

  • The BU-Net bias correction model significantly improves the forecast performance of WW3

  • The predicting scheme improves the forecast performance during typhoon passages

Cryosphere

Open Access

Inventory and Frequency of Retrogressive Thaw Slumps in Permafrost Region of the Qinghai–Tibet Plateau

  • First Published: 09 December 2022
Key Points

  • Two thousand six hundred and sixty nine active retrogressive thaw slumps (RTSs) were identified in the permafrost regions of the Qinghai–Tibet Plateau

  • RTSs significantly increased in number and area, mainly in 2010 and 2016 when summer temperatures were extremely high

  • Intensification of RTSs could occur in the future in association with higher air temperatures appear in thawing season

Solid Earth

Open Access

Robust Seismic Images of the Hawaiian Plume

  • First Published: 01 December 2022
Key Points

  • A robust 3-D Vs model beneath Hawaii is obtained by inverting three kinds of seismic data

  • The Hawaiian plume is imaged as a continuous low-Vs zone down to ∼700 km depth

  • Our results reveal the Pacific lithosphere dragging plume, rejuvenation and re-aging

Space Sciences

Open Access

MAVEN Proton Observations Near the Martian Moon Phobos: Does Phobos Backscatter Solar Wind Protons?

  • First Published: 01 December 2022
Key Points

  • Mars Atmosphere and Volatile EvolutioN mission (MAVEN) flew by Phobos 15 times at a distance lower than 370 km

  • We find no evidence of solar wind protons backscattered by the surface of Phobos in the MAVEN proton measurements

  • Foreshock—shock foot protons and exospheric pickup protons are often detected and can be misidentified as solar wind backscattered protons

Atmospheric Science

Open Access

Tropospheric Ozone During the Last Interglacial

  • First Published: 01 December 2022
Key Points

  • Clumped isotopes of tropospheric oxygen are less abundant during the Last Interglacial than during the late pre-industrial Holocene

  • The clumped-isotope data indicate less tropospheric ozone in the Last Interglacial than the pre-industrial Holocene

  • Larger pre-industrial tropospheric ozone burden is compatible with elevated biomass burning after late-Pleistocene megafaunal extinctions

Open Access

The Role of Atmospheric Transport for El Niño-Southern Oscillation Teleconnections

  • First Published: 23 November 2022
Key Points

  • Transported air from the Equatorial Pacific (EP) shows significant anomalies in moisture and heat compared to its environment

  • The transport of anomalously dry or wet air can be linked to several observed atmospheric teleconnections associated with El Niño Southern Oscillation

  • Deposition of excess energy into the Atlantic Ocean can directly be linked to energetic air from the EP

Solid Earth

Open Access

Transition From Slow to Fast Injection-Induced Slip of an Experimental Fault in Granite Promoted by Elevated Temperature

  • First Published: 05 December 2022
Key Points

  • Elevated temperature promotes a more uniform fluid pressure distribution over the fault surface mainly by reducing water viscosity

  • Accelerated and enhanced fault healing at elevated temperature causes faster fault slip rates upon injection-induced fault failure

  • The injection-induced seismic hazard is enhanced in higher-temperature geothermal reservoirs and deeper part of the reservoirs

Cryosphere

Open Access

Changes in Antarctic Ice Sheet Motion Derived From Satellite Radar Interferometry Between 1995 and 2022

  • First Published: 05 December 2022
Key Points

  • We present historical, continent-wide, mosaics of Antarctic ice motion using a suite of satellite sensors spanning 28 years

  • We report areas of accelerated flow stretching over 100 km's from the coast and the entire drainage of the Amundsen Sea Embayment sector

  • The observed, ongoing, detailed glacier changes will help constrain ice sheet numerical models in charge of reconstruction and projection

Solid Earth

Open Access

Downgoing Plate-Buoyancy Driven Retreat of North Sulawesi Trench: Transition of a Passive Margin Into a Subduction Zone

  • First Published: 16 November 2022
Key Points

  • Subduction initiation of the North Sulawesi subduction zone is induced, but the trench retreat is driven by the subducted plate itself

  • Subduction-driven mantle flow plays a vital role in trench motion and upper plate deformation

  • The reason for the current clockwise rotation of the North Arm of Sulawesi is due to the presence of the underlying Sangihe slab

Oceans

Open Access

Seaward-Dipping Reflector Influence on Seafloor Magnetostratigraphy—A Pelotas Basin View

  • First Published: 28 November 2022
Key Points

  • Some magnetic anomalies interpreted as related to vertical fabric oceanic crust are related to seaward-dipping reflectors (SDRs)

  • Seaward-dipping reflectors are different from typical oceanic crust in geometry and compositional heterogeneity

  • SDR-related magnetic anomalies should not be used to constrain ages

Cryosphere

Open Access

Shallow Fracture Buffers High Elevation Runoff in Northwest Greenland

  • First Published: 28 November 2022
Key Points

  • We identify extensive meltwater infiltration and refreezing beneath low-permeability ice slabs in Northwest Greenland

  • These buried ice complexes form where supraglacial lakes or streams drain through shallow surface crevasses into the relict firn

  • This process reduces ice-slab induced runoff and limits the immediate impact of high-elevation surface melting on ice dynamics

Climate

Open Access

CCHZ-DISO: A Timely New Assessment System for Data Quality or Model Performance From Da Dao Zhi Jian

  • First Published: 05 December 2022
Key Points

  • A Timely New Assessment System for data quality or model performance is established

  • Chen, Chen, Hu, and Zhou (CCHZ)-distance between indices of simulation and observation (DISO) has the advantage to evaluate the overall performance of different models for multiple variables and add the weights of metrics

  • CCHZ-DISO can be widely used to quality the model performance in any subjects

Open Access

Reconstruction of Zonal Precipitation From Sparse Historical Observations Using Climate Model Information and Statistical Learning

  • First Published: 05 December 2022
Key Points

  • Detection and attribution of change in the water cycle is difficult due to sparse observations, model uncertainty, and internal variability

  • We reconstruct the inter-annual variability of zonal mean precipitation from gauge data using regularized regression techniques

  • We demonstrate that the observed multi-decadal zonal water cycle changes lie within the range of historical climate model simulations

Atmospheric Science

Open Access

Biases in CMIP6 Historical U.S. Severe Convective Storm Environments Driven by Biases in Mean-State Near-Surface Moist Static Energy

  • First Published: 21 October 2022
Key Points

  • Most models reproduce the pattern of severe convective storm (SCS) environments over North America, and some also reproduce the magnitude

  • Spring SCS environment biases are driven by mean-state near-surface moist static energy biases

  • Hence, simulating SCS environments well requires simulating the near-surface mean state air properties well

Climate

Open Access

Tropical Indian Ocean Warming Contributes to Arctic Warming

  • First Published: 05 December 2022
Key Points

  • Rapid warming in the Indian Ocean (IO) may contribute to the Arctic warming through both oceanic and atmospheric pathways

  • More ocean heat is transported from the North Atlantic to the Arctic due to enhanced Atlantic Meridional Overturning Circulation in response to the IO warming

  • Southerly winds in the high latitudes in response to the IO warming convey more warm air into parts of the Arctic

Oceans

Open Access

Why Is Seasonal Density Stratification in Shelf Seas Expected to Increase Under Future Climate Change?

  • First Published: 15 November 2022
Key Points

  • Seasonal stratification in shelf seas is expected to increase under global heating

  • The increase in thermal expansivity with temperature increases the buoyancy forcing that drives seasonal stratification

  • The close balance between buoyancy input and mixing amplifies this effect leading to large relative changes in stratification

Open Access

Cobalamin Co-Limits Phytoplankton and Bacterial Biomass and Activity in Eastern Mediterranean Coastal Waters

  • First Published: 23 November 2022
Key Points

  • Addition of B12 increased pico/nano-eukaryotes abundance during the illuminated hours and of cyanobacteria during night-time

  • B12 amendments accelerated NO3 uptake by phytoplankton, resulting in increased primary production rates

  • Phytoplankton were co-limited by NO3 and B12 while heterotrophic bacteria were co-limited by B12 and PO4

Planets

Open Access

Surface Features of Ganymede Revealed in Jupiter-Shine by Juno’s Stellar Reference Unit

  • First Published: 12 December 2022
Key Points

  • Juno’s Stellar Reference Unit imaged Ganymede at high resolution and incidence angle while the surface was illuminated by Jupiter-shine

  • Grooved material, ejecta, and multiple craters are now resolved, enabling improved mapping of a 2 × 105 km2 region in Xibalba Sulcus

  • The unique morphology of a possible 270-km scar from comet fragments, or a highly isolated distal ray from Tros, is revealed

Oceans

Open Access

South Pacific Ocean Dynamics Redistribute Ocean Heat Content and Modulate Heat Exchange With the Atmosphere

  • First Published: 29 November 2022
Key Points

  • Wind-driven ocean adjustment explains much of the change in ocean heat content and the flux of heat to the atmosphere

  • The heat exchange attributed to the Rossby waves, after seasonality is removed, ranges from −9 to 21 W m−2

  • The results suggest forecasted heat fluxes due to Rossby waves could provide predictability on ocean heat exchange with the atmosphere

Space Sciences

Open Access

Does Uranus' Asymmetric Magnetic Field Produce a Relatively Weak Proton Radiation Belt?

  • First Published: 23 November 2022
Key Points

  • Asymmetry in Uranus' magnetic field perturbs motion of radiation belt particles with respect to their motion in a planet-centered dipole

  • This perturbation is more significant the greater the gyroradius of the particle, making the highest energy ions the most affected

  • Degraded trapping of these particles compared to a planet-centered dipole may explain the weak proton radiation belt observed by Voyager 2

Climate

Open Access

East Asian Monsoonal Climate Sensitivity Changed in the Late Pliocene in Response to Northern Hemisphere Glaciations

  • First Published: 05 December 2022
Key Points

  • Cyclic patterns in East Asian summer monsoonal intensity during the Pliocene were mainly driven by Antarctic ice sheet variations

  • A major reorganization of the East Asian climate system occurred at 2.75–2.6 Ma in response to Northern Hemisphere glaciation

  • Quaternary East Asian summer monsoon on orbital scales displays a sensitivity that is unique to the modern icehouse with bipolar ice sheets

Solid Earth

Open Access

Chasing Tails: Insights From Micromagnetic Modeling for Thermomagnetic Recording in Non-Uniform Magnetic Structures

  • First Published: 28 November 2022
Key Points

  • Micromagnetic models of elongate 100 nm magnetite grains suggest several stable domain states that change as a function of temperature

  • The preferred state is also a function of cooling rate and so blocking and unblocking of remanence depends on the thermal history

  • Such particles will likely have unequal blocking and unblocking temperatures causing Arai plot curvature and biased paleointensity estimates

Atmospheric Science

Open Access

The First Seasonal Snowfall Impacts Plant Photosynthesis and Monoterpene Emissions

  • First Published: 23 November 2022
Key Points

  • Leaf-level monoterpene emissions are independent of stomatal condition following a snow event

  • Senescence has a non-linear impact on both the magnitude and identity of monoterpene emissions

  • Structural similarity of monoterpene isomers does not predict emission trends

Space Sciences

Free Access

Evidence for Magnetic Reconnection at Ganymede's Upstream Magnetopause During the PJ34 Juno Flyby

  • First Published: 12 December 2022
Key Points

  • Juno observed enhanced electron fluxes and cold protons and heavy ions near its crossing of Ganymede's upstream magnetopause

  • Accelerated, field-aligned electrons observed near Ganymede's magnetopause provide evidence for magnetic reconnection

  • Counter-streaming electrons observed across the magnetopause suggest reconnection sites both north and south of the spacecraft

Open Access

Relativistic Microburst Scale Size Induced by a Single Point-Source Chorus Element

  • First Published: 09 December 2022
Key Points

  • We use an event-based model with propagation in an inhomogeneous magnetosphere to study chorus-induced relativistic microburst scale size

  • A primary precipitation burst is seen near the wave source field line by resonance with quasi-parallel waves near equatorial source region

  • A secondary precipitation burst is seen on more poleward L-shell by resonance with high latitude oblique waves with scale size 20–40 km

Cryosphere

Open Access

Correspondence Among Mid-Latitude Glacier Equilibrium Line Altitudes, Atmospheric Temperatures, and Westerly Wind Fields

  • First Published: 14 November 2022
Key Points

  • Mid-latitude glacier annual equilibrium line altitude corresponds to broad regions of atmospheric temperature

  • Mid-latitude glacier annual equilibrium line altitude is sensitive to latitudinal shifts of the mid-latitude westerlies

  • The influence of the westerlies on glaciers has important implications for interpreting past and predicting future climate change

Climate

Open Access

Net Equatorward Shift of the Jet Streams When the Contribution From Sea-Ice Loss Is Constrained by Observed Eddy Feedback

  • First Published: 10 December 2022
Key Points

  • Antarctic and Arctic sea-ice loss cause an equatorward shift of the winter jet stream in the southern and northern hemisphere, respectively

  • Models with stronger eddy feedback simulate farther jet shifts in response to both Antarctic and Arctic sea-ice loss

  • Observationally constrained equatorward jet shifts due to sea-ice loss exceed in magnitude the simulated poleward shifts due to ocean warming

Space Sciences

Free Access

Ganymede's Radiation Cavity and Radiation Belts

  • First Published: 12 December 2022
Key Points

  • Ganymede's radiation cavity has lower intensities compared to Jupiter

  • Ganymede has a radiation belt of at least tens and hundreds of keV ions and electrons

  • Ganymede's radiation belt cannot be produced through influx of Jupiter particles alone

Hydrology and Land Surface Studies

Open Access

Defining the Bounds of Using Radioactive Isotope Tracers to Sense Past Groundwater Recharge Under Transient State Conditions

  • First Published: 14 November 2022
Key Points

  • Radioactive isotopes preserve transient groundwater behavior with timeframes consistent with their half-life

  • Transient behavior can be identified using a visual interpretation of a log-scaled change in concentration with distance plot

  • Graphical interpretation allows determination of the timing of an environmental change influencing groundwater recharge

Space Sciences

Open Access

Flow Channels and the Generation of Alfvénic Turbulence Along Storm-Time Inner Magnetospheric Field-Lines

  • First Published: 23 November 2022
Key Points

  • Fast flow channels in the storm-time inner-magnetosphere may be unstable to the Kelvin-Helmholtz instability

  • The Kelvin-Helmholtz instability and wave reflection from the ionosphere generate a broad spectrum of turbulent Alfvénic field variations

  • The properties of the turbulent fields generated from sheared flows and reflection replicate those observed from spacecraft

Planets

Free Access

Ganymede's UV Reflectance From Juno-UVS Data

  • First Published: 12 December 2022
Key Points

  • Juno ultraviolet spectrograph mapped UV sunlight reflected by Ganymede's surface during the Juno orbit 34 Ganymede flyby

  • The UV signature of pure water ice was detected in the north polar regions but not within other ice-rich regions including Tros crater

  • Additional absorption features observed may be related to ammonia and ozone

Climate

Open Access

A Shifting Tripolar Pattern of Antarctic Sea Ice Concentration Anomalies During Multi-Year La Niña Events

  • First Published: 16 November 2022
Key Points

  • The typical sea ice anomaly pattern appears during the second winter of multi-year La Niñas but was zonally shifted during the first winter

  • The shifted pattern results from an unique pre-onset Indian ocean condition of multi-year La Niña and atmospheric teleconnections it excites

  • The different sea ice impacts revealed in the CESM1 simulation appear in four of the six observed multi-year La Niña events during 1979–2020

Atmospheric Science

Open Access

A Self-Sustained Charge Neutrality Intracloud Lightning Parameterization Containing Channel Decay and Reactivation

  • First Published: 28 November 2022
Key Points

  • Channel decay and reactivation are considered in lightning parameterization schemes with explicit channels for the first time

  • Self-sustained charge neutrality and simultaneous development of multiple branches are realized

  • Time-varying nonlinear electrical parameters including channel electric field, current, and conductivity are provided during the simulation

Solid Earth

Open Access

Imaging the Northeastern Crustal Boundary of the Tibetan Plateau With Radial Anisotropy

  • First Published: 23 November 2022
Key Points

  • We construct a high-resolution radial anisotropic velocity model for northeastern (NE) Tibet and its surroundings

  • Different crustal radial anisotropy in Qilian orogen and Songpan-Ganzi Terrane indicate different stages of crustal deformation in NE Tibet

  • The distribution of crustal radial anisotropy clearly defines the NE crustal boundary of the expanding portion of Tibet

Climate

Open Access

Relative Roles of Land and Ocean Cooling in Triggering an El Niño Following Tropical Volcanic Eruptions

  • First Published: 12 December 2022
Key Points

  • Pinatubo aerosol forcing is set over land and ocean respectively to investigate roles of land and ocean cooling in exciting an El Niño

  • The volcano-induced land cooling, especially tropical African cooling, plays an essential role in exciting an El Niño following eruptions

  • The oceanic volcanic forcing could induce a fast dipole response in the Indian Ocean, exciting a slow western Pacific El Niño-like cooling

Oceans

Open Access

Modulation of the Eastern Equatorial Pacific Seasonal Cycle by Tropical Instability Waves

  • First Published: 14 November 2022
Key Points

  • Feedbacks from tropical instability waves (TIWs) on the eastern equatorial Pacific Ocean seasonal cycle are quantified

  • TIWs reduce the amplitude of the upper equatorial ocean temperature seasonal cycle by warming equatorial waters in boreal summer and fall

  • TIWs stabilize and weaken the upper Equatorial Undercurrent year-round and prevent its re-intensification in boreal fall

Atmospheric Science

Open Access

A Case Study of Cumulus Convection Over Land in Cloud-Resolving Simulations With a Coupled Ray Tracer

  • First Published: 05 December 2022
Key Points

  • We present graphics processing unit-accelerated cloud-resolving simulations with a coupled ray tracer

  • Simulated cloud statistics are insensitive to ray tracer convergence across a wide range of sample sizes

  • Strong coupling between surface irradiance patterns and cloud evolution underlines need for coupled 3D radiative transfer

Space Sciences

Open Access

Electron Behavior Around the Onset of Magnetic Reconnection

  • First Published: 05 December 2022
Key Points

  • Signatures indicating reconnection onset can be identified in the electron distributions

  • Onset signatures persist over extended spatial and temporal scales

  • The particle distributions immediately preceding onset are characterized by features of non-gyrotropy and acceleration

Climate

Open Access

The Multi-Decadal Response to Net Zero CO2 Emissions and Implications for Emissions Policy

  • First Published: 16 November 2022
Key Points

  • The conditions for stabilization of global temperature at any level depend on the multi-century carbon and thermal cycle response

  • This is described by the rate of adjustment to zero emissions parameter, spanning −0.24 to +0.17%/yr (−0.036 to 0.025°C/decade at 1.5°C)

  • In 1.5°C scenarios, CO2 emissions consistent with halting anthropogenic warming over multi-decadal timescales span −7.3 to +6.2 GtCO2/yr

Cryosphere

Open Access

Significant Latitudinal Gradient of Nitrate Production in the Marine Atmospheric Boundary Layer of the Northern Hemisphere

  • First Published: 16 November 2022
Key Points

  • Continental sources dominated atmospheric NO3 across NH, with oceanic RONO2 emissions contributing 21%–26% to NO3 in mid-latitudes

  • Slightly higher δ15N in Arctic versus mid-latitudes suggests that isotope effects of atmospheric transport of NO3 were not significant

  • In summer, 69% of NO3 is formed via NO2 + OH channel in the Arctic and 68% of NO3 is from N2O5 + H2O and NO3 + DMS/CH pathways in mid-latitudes

Solid Earth

Open Access

Coseismic Folding During Ramp Failure at the Front of the Sulaiman Fold-and-Thrust Belt

  • First Published: 16 November 2022
Key Points

  • 2015 Mw 5.7 Dajal, Pakistan earthquake ruptured the blind front of the Sulaiman Fold Thrust belt

  • Coseismic deformation includes slip on a blind thrust and flexural slip in the hanging wall

  • The buried section of the Boundary Thrust extends 30 km farther south of the fault trace

Oceans

Open Access

Improving and Harmonizing El Niño Recharge Indices

  • First Published: 07 November 2022
Key Points

  • To clarify the debate on the Recharge Oscillator index, we develop an objective approach optimizing equation fit to observations

  • The recharge index must be based on the slow component of sea level/thermocline depth, taken independently from the fast zonal tilt mode: this reconciles usual metrics

  • The optimal index is this independent component averaged in the equatorial and southwestern Pacific. It is better suited for operational diagnostics

Atmospheric Science

Open Access

Competition Between Radiative and Seeding Effects of Overlying Clouds on Underlying Marine Stratocumulus

  • First Published: 12 December 2022
Key Points

  • Competition between the radiative and seeding effects of overlying clouds on stratocumulus (Sc) is quantified at a global scale

  • The global net effect of overlying clouds suppresses the vertical development and thus reduces precipitation of underlying Sc

  • Thicker seeder clouds (optical depth >0.16) can reverse the change in Sc precipitation from radiative suppression to seeding enhancement

Solid Earth

Open Access

Monitoring Seasonal Shear Wave Velocity Changes in the Top 6 m at Garner Valley in Southern California With Borehole Data

  • First Published: 05 December 2022
Key Points

  • We use earthquake and cross-hole experiment data at Garner Valley, CA, to monitor shear wave velocity variations in shallow materials

  • The seasonal variation of shear wave velocity is up to ∼25% in the top 6 m, mainly caused by pore pressure changes

  • The changes of shallow seismic properties are relevant to ground motion hazard and environmental seismology

Climate

Open Access

Common Error Patterns in the Regional Atmospheric Circulation Simulated by the CMIP Multi-Model Ensemble

  • First Published: 23 November 2022
Key Points

  • Global climate models (GCMs) have common regional atmospheric circulation error patterns in the northern hemisphere extratropics

  • Similar error patterns are obtained for GCMs using the same atmospheric general circulation model (AGCM) family and, unexpectedly, also for some GCMs using different AGCM families

  • A set of weighting factors documenting the degree of statistical independence is provided which is virtually unrelated to model performance

Atmospheric Science

Open Access

The Delayed Response of the Troposphere-Stratosphere-Mesosphere Coupling to the 2019 Southern SSW

  • First Published: 30 November 2022
Key Points

  • A rare Southern Hemisphere sudden stratospheric warming event occurred in September 2019 and contributed to the early onset of polar mesospheric clouds in November

  • The downward propagation of the zonal wind anomaly affects the propagation of planetary waves (PWs) by modulating barotropic/baroclinic instability

  • The secondary enhanced upward propagation of the PWs causes a delayed response in both the polar stratosphere and mesosphere

Climate

Open Access

An Extratropical Contribution to the Signal-To-Noise Paradox in Seasonal Climate Prediction

  • First Published: 23 November 2022
Key Points

  • Tropical relaxation is used to test whether the mid-latitude “signal-to-noise paradox” can be removed by specifying the tropical state

  • This is found not to be the case, implying that at least part of the paradox is due to errors in simulating processes in the extratropics

  • The results have implications for narrowing the identification of the source of the paradox

Solid Earth

Open Access

Mapping Vertical Land Motion in Challenging Terrain: Six-Year Trends on Tutuila Island, American Samoa, With PS-InSAR, GPS, Tide Gauge, and Satellite Altimetry Data

  • First Published: 23 November 2022
Key Points

  • Redundant persistent scatterer-interferometric synthetic aperture radar analysis, with GPS and joint tide gauge/satellite altimetry data, reveals coastal vertical land motion trends despite challenging terrain

  • Subsidence rates of 6–9 mm/yr are observed on Tutuila Island from late-2015 to mid-2022

  • Locations of stronger subsidence are identified at Pago Pago International Airport and Pago Pago Harbor

Space Sciences

Open Access

Alternating North-South Brightness Ratio of Ganymede's Auroral Ovals: Hubble Space Telescope Observations Around the Juno PJ34 Flyby

  • First Published: 12 December 2022
Key Points

  • Hubble Space Telescope observations of Ganymede's orbitally trailing hemisphere on 7 June 2021 in support of Juno flyby

  • Brightness ratio of northern and southern auroral ovals oscillates such that the oval facing the Jovian plasma sheet is brighter

  • Oscillation suggests the aurora is driven by magnetic stresses coupling the moon's magnetic field to the surrounding Jovian plasma sheet

Climate

Open Access

Non-Linear Response of the Extratropics to Tropical Climate Variability

  • First Published: 23 November 2022
Key Points

  • Stronger weakening of the stratospheric polar vortex is found during Quasi-biennial Oscillation-easterly phase and El Nino combined

  • Non-linear polar vortex weakening is found in both model and observations

  • The polar vortex non-linearity impacts surface pressure and temperature, which has implications for seasonal forecasting

Solid Earth

Open Access

Silent Very Long Period Seismic Events (VLPs) at Stromboli Volcano, Italy

  • First Published: 28 November 2022
Key Points

  • Seismo-acoustic observations from Stromboli in 2018 show hundreds of repeating very long period (VLP) seismic signals without corresponding acoustic signals

  • VLPs without explosions suggest the slug model is a poor fit for “normal” activity at Stromboli

  • We suggest VLPs may instead result from large gas bubbles interacting with a semi-permeable solid plug

Open Access

Continental Mid-Lithosphere Discontinuity: A Water Collector During Craton Evolution

  • First Published: 23 November 2022
Key Points

  • The dynamics of craton evolution and mid-lithosphere discontinuity (MLD) formation is investigated by numerical models with a new and simplified deep hydration method

  • The MLD may be induced by slow hydration within the mantle lithosphere and acts as a water collector during long-term craton evolution

  • The MLD represents the top boundary of a hydrated layer with high water content and low shear-wave velocity within cratonic lithosphere

Open Access

Plume-Induced Rifting of Thickened Crust: 2D Numerical Model and Implications for N–S Rifts in Southern Tibet

  • First Published: 05 December 2022
Key Points

  • Small-scale mantle plume penetration into the lithospheric weak zone promotes rifting in thickened crust

  • The presence of a heterogeneous weak mid-crustal zone and small-scale plume leads to multiple crustal-scale rifts

  • Modeled multiple rifting is in agreement with a series of N–S rifts in southern Tibet

Atmospheric Science

Open Access

Derivation of Emissions From Satellite-Observed Column Amounts and Its Application to TROPOMI NO2 and CO Observations

  • First Published: 16 November 2022
Key Points

  • A unified framework that connects emissions with satellite-observed column amounts is derived from the principle of mass conservation

  • Wind divergence, topography, and chemistry are considered, making this framework applicable to a range of atmospheric species

  • Unprecedented details in the emissions of air pollutants are unveiled by applying this framework to TROPOspheric Monitoring Instrument NO2 and CO products

Space Sciences

Free Access

Plasma Observations During the 7 June 2021 Ganymede Flyby From the Jovian Auroral Distributions Experiment (JADE) on Juno

  • First Published: 01 July 2022
Key Points

  • The plasma observations show that Juno crossed into the open field line region, but do not support crossing into a closed field line region

  • The ion composition near Ganymede is very different from its local plasma environment

  • H2+ and H3+ ions were detected inside Ganymede's magnetopause and outside in the wake region

Open Access

Magnetosonic Waves Above the Lower Hybrid Frequency in Cyclotron Resonance With the Van Allen Radiation Belt Electrons

  • First Published: 23 November 2022
Key Points

  • Electron cyclotron resonance can extend to 10–100s keV for the high-frequency, non-quasi-perpendicular, plasmaspheric magnetosonic waves

  • The f > flh magnetosonic waves occur mainly in the duskside outer plasmasphere, with an average amplitude of 10 pT following strong substorms

  • The f > flh magnetosonic waves are probably generated by the proton Bernstein-mode instability at midlatitudes in the outer plasmasphere

Atmospheric Science

Open Access

Direct Observation of the Transitional Stage of Mixing-State-Related Absorption Enhancement for Atmospheric Black Carbon

  • First Published: 09 December 2022
Key Points

  • A transitional stage of the absorption enhancement (Eabs) during the evolution of black carbon (BC) was directly observed in the ambient

  • By tracking the evolution of fresh BC, the predicted Eabs based on the particle-resolved model showed consistent transitional stage

  • The secondary inorganic species acted the most critical role in the coating materials to enhance the absorption of BC-containing particles

Planets

Open Access

Ganymede Observations by JunoCam on Juno Perijove 34

  • First Published: 12 December 2022
Key Points

  • In 2021, Juno camera (JunoCam) acquired close-up images of Ganymede, providing improved spatial resolution relative to the 1979 Voyager 1 coverage

  • While no changes were observed in the 42 years since Voyager, previously unrecognized paterae and craters were identified

  • Topography derived from JunoCam confirmed a 3 km high dome at Ganymede's subjovian point and showed it to be elliptical in planform

Climate

Open Access

Significant Contribution of Paleogeography to Stratospheric Water Vapor Variations in the Past 250 Million Years

  • First Published: 09 December 2022
Key Points

  • Both CO2 concentration and paleogeography have prominent influence on the Stratospheric water vapor (SWV) variations in the past 250 million years

  • The SWV increases with surface warming and stratospheric moistening rate is accelerated during warm periods

  • The ratio of stratospheric moistening to surface warming is sensitive to the continental configurations in warmer climates

Solid Earth

Open Access

High-Rate Fluid Injection Reduces the Nucleation Length of Laboratory Earthquakes on Critically Stressed Faults in Granite

  • First Published: 05 December 2022
Key Points

  • The nucleation length of injection-induced laboratory earthquakes reduces with higher injection rate and greater effective normal stress

  • Injection-induced laboratory earthquakes with smaller nucleation lengths exhibit higher peak slip rates and larger fault slip displacements

  • Fast-rate fluid injection may cause initially stable fault patches of smaller sizes to slip seismically, leading to higher seismic hazards

Atmospheric Science

Open Access

A Surface Flux Estimation Scheme Accounting for Large-Eddy Effects for Land Surface Modeling

  • First Published: 07 December 2022
Key Points

  • Surface momentum flux estimation formula considering large eddy effects in unstable boundary layer is further simplified

  • The simplified surface momentum flux estimation formula reflects the varying vertical extent of largest eddies

  • These results are obtained by confining the vertical extents of largest eddies in a wide range of depths in large eddy simulations

Climate

Open Access

Extratropical Stratospheric Air Intrusions Over the Western North Pacific and the Genesis of Downstream Monsoon Low-Pressure Systems

  • First Published: 28 November 2022
Key Points

  • The study brings out the role of extratropical stratospheric intrusions in triggering low-level vortex seeds over the western North Pacific (WNP)

  • Forty-three percentage of the downstream low-pressure systems are caused by the extratropical stratospheric air intrusions over the WNP

  • Low-level cyclonic vortices are induced by dynamic lifting to the southwest of the extratropical stratospheric air intrusions

Atmospheric Science

Open Access

Microphysical Structure of Thunderstorms and Their Lightning Activity During the mei-yu and Post-mei-yu Periods Over Nanjing, Yangtze River Delta

  • First Published: 16 November 2022
Key Points

  • The mei-yu thunderstorms produced much less cloud-to-ground lightning than post-mei-yu thunderstorm

  • Graupel during the mei-yu and post-mei-yu periods showed different microphysical characteristics

  • The environmental condition plays an important role in controlling thunderstorm microphysics during the mei-yu and post-mei-yu periods