Uncertainty in Arctic top-of-atmosphere (TOA) radiative flux observations stems from the low sun angles and the heterogeneous scenes. Advancing our understanding of the Arctic climate system requires improved TOA radiative fluxes. We compare Cloud and Earth’s Radiant Energy System (CERES) TOA radiative fluxes with Arctic Radiation-IceBridge Sea and Ice Experiment (ARISE) airborne measurements using two approaches: grid box averages and instantaneously-matched footprints. Both approaches indicate excellent agreement in the longwave and good agreement in the shortwave, within 2 uncertainty considering all error sources (CERES and airborne radiometer calibration, inversion, and sampling). While the SW differences are within 2 uncertainty, both approaches show a ~‑10 W m‑2 average CERES-aircraft flux difference. Investigating the source of this negative difference, we find a substantial sensitivity of the flux differences to the sea ice concentration dataset. Switching from imager-based to passive microwave-based sea ice data in the CERES inversion process reduces the differences in the grid box average fluxes and in the sea ice partly cloudy scene anisotropy in the matched footprints. In the long-term, more accurate sea ice concentration data are needed to reduce CERES TOA SW flux uncertainties. Switching from imager to passive microwave sea ice data, in the short-term, could improve CERES TOA SW fluxes in polar regions, additional testing is required. Our analysis indicates that calibration and sampling uncertainty limit the ability to place strong constraints (<±7%) on CERES TOA fluxes with aircraft measurements.

The Coast of Louisiana is affected by accelerating sea level rise compounded by land subsidence, leading to land loss. Vertical crustal motions in the region are caused by natural and anthropogenic processes that vary temporally and spatially across the Gulf of Mexico. We investigate the role of growth faulting contributions to subsidence in a case study of Baton Rouge, where two E-W striking, down-to-the-south normal faults, the Denham Springs and Baton Rouge faults, cut compacted Pleistocene strata, and where sediment compaction should be minimal. We used InSAR time series and LiDAR differencing data spanning 1999-2020 to quantify modern vertical and horizontal displacements. After calibration with GNSS data, both methods reveal similar spatial patterns in ground motion, with the faults delimiting areas with different absolute rates. On average the area north of the Baton Rouge fault is subsiding faster than the south, opposite to the long-term sense of fault slip. LiDAR mean vertical rates range between -5 to -11 mm/y and -2.4 to -7 mm/y. InSAR time-series mean rates in the LOS direction range between -10.9 to -13.6 mm/y and -8 to -10.6 mm/y, respectively, for the north and south areas. Subsidence in the northern area likely is controlled by groundwater level changes caused by pumping as indicated by groundwater extraction models. The southern area average is likely influenced by the injection of fluids. Our results suggest volumetric changes caused by fluid extraction and injection in regions separated by growth faults that are creeping to accommodate the spatial variations in subsidence.

Now published: Spilling K, Heinemann M, Vanharanta M, et al. (2023) Respiration rate scales inversely with sinking speed of settling marine aggregates. PLoS ONE 18(3): e0282294. https://doi.org/10.1371/journal.pone.0282294 Sinking marine particles have been studied for a long time to understand its role in carbon sequestration. Traditionally, sinking speed and respiration rates have been treated as independent variables, but two recent papers suggest a connection albeit in contrasting directions. Alcolombri et al. [2021] demonstrated that slow moving particles are respired faster than motionless particles, whereas García‐Martín et al. [2021] found that respiration rate was higher for suspended particles compared with slow- and fast-sinking particles. Here we collected settling aggregates and determined respiration rates of particles sinking at different velocities. The average respiration rate of fast sinking particles (>100 m d-1) was 0.12 d-1. Slower sinking particles (<50 m d-1) had on average higher and more variable respiration rates. These findings provide insights into the efficiency of the biological carbon pump and help resolve the apparent discrepancy in the recent studies of the correlation between respiration and sinking speed. Alcolombri, U., F. J. Peaudecerf, V. I. Fernandez, L. Behrendt, K. S. Lee, and R. Stocker (2021), Sinking enhances the degradation of organic particles by marine bacteria, Nat Geosci, 1-6. García‐Martín, E. E., K. Davidson, C. Davis, C. Mahaffey, S. Mcneill, D. Purdie, and C. Robinson (2021), Low contribution of the fast‐sinking particle fraction to total plankton metabolism in a temperate shelf sea, Glob Biogeochem Cycles, 35(9), e2021GB007015.

Triaxial compression experiments were carried out on samples of fine-grained Aji granite to measure the evolution of permeability during deformation prior to failure under confining pressures of 20 and 40 MPa. During the initial stages of deformation, a small decrease in permeability was observed, due to the closure of pre-existing microcracks; permeability then increased with increasing differential stress. During deformation, permeability varied by up to two orders of magnitude, and we observed a small pressure dependence, with a larger variation observed at 20 MPa than at 40 MPa. This suggests that more cracks developed during brittle deformation under the lower confining pressure. The observed increase in permeability during our experiments was approximately proportional to inelastic volumetric strain, which corresponded to the volume of dilatant cracks. On the other hand, prior to brittle failure we observed a further increase in permeability that was greater than the inelastic volumetric strain, suggesting crack aperture opening accelerated at this stress level (>~80%).

One of the challenges in the numerical weather models is the adequate representation of soil-vegetation-atmosphere interaction at different spatial scales, including scenarios with heterogeneous land cover and complex mountainous terrain. The interaction determines the energy, mass and momentum exchange at the surface and could affect different variables including precipitation, temperature, and wind. In order to quantify the long-term climate impact of changes in local land use and to assess the role of topography, two numerical experiments were examined. The first experiment allows assessing the continuous growth of urban areas within the Aburrá Valley, a complex terrain region located in Colombian Andes. The Weather Research Forecast model (WRF) is used as the basis of the experiment. The basic setup involves two nested domains, one representing the continental scale (18 km) and the other the regional scale (2 km). The second experiment allows drastic topography modification, including changing the valley configuration to a plateau. The control run for both experiments corresponds to a climatological scenario. In both experiments, the boundary conditions correspond to the climatological continental domain output. Surface temperature, surface winds, and precipitation are used as the main variables to compare both experiments relative to the control run. The results of the first experiment show a strong relationship between land cover and the variables, especially for surface temperature and wind speed, due to the strong forcing land cover imposes on the albedo, heat capacity and surface roughness, changing temperature and wind speed magnitudes. The second experiment removes the winds spatial variability related to hill slopes, the direction and magnitude is modulated only by the trade winds and roughness of land cover.

Blue corona discharges are bursts of streamers often observed at the top of thunderclouds, but the cloud conditions that facilitate them are not well known. Here we present observations by the Atmosphere-Space Interactions Monitor of 92 corona discharges as it passed over cyclone Fani in the Bay of Bengal. The discharges formed in convective cells of unstable air carried from land over the Indian Ocean, with CAPE reaching ~6000 J kg-1. The CALIPSO satellite passed over one of the cells ~12 min after ASIM, taking the first measurements of the microphysics at the top of a cloud generating corona discharges. We find the discharges occur in a region of strong convection, the cloud reaching into the stratosphere with ice/water content ~0.1 g m-3, photon mean free path ~ 3 m and ice crystal number density ~5e7 m-3. Measurements by a lightning detection network suggest the charge structures are folded.

The International Ocean Discovery Program cored Sites U1517 (Tuaheni landslide complex) and U1519 (upper Tuaheni Basin) on the Hikurangi margin, North Island, New Zealand. Strong ocean currents result in unusual amounts of compositional homogeny in the muds. Detrital smectite dominates among clay minerals, with average proportions of 52 wt% at Site U1517 and 53 wt% at Site U1519. Bulk sediment from Site U1517 contains up to ~29 wt% smectite (average = 21 wt%), high enough to reduce the angle of internal friction (on average) to ~6°. There are no compositional excursions along inferred slip surfaces or weak layers. Smectite decreases toward the SW in the “downstream” direction of the East Cape Current, and that spatial trend correlates with lower densities of slide scars.

This study quantifies the contribution to Arctic winter surface warming from changes in the tropospheric energy transport (Ftrop) and the efficiency with which Ftrop heats the surface in the RCP8.5 warming scenario of the CESM Large Ensemble. A metric for this efficiency, Etrop, measures the fraction of anomalous Ftrop that is balanced by an anomalous net surface flux (NSF). Drivers of Etrop are identified in synoptic-scale events during which Ftrop is the dominant driver of NSF. Etrop is sensitive to the vertical structure of Ftrop and pre-existing Arctic lower-tropospheric stability (LTS). In RCP8.5, winter mean Ftrop decreases by 9.5 Wm–2, while Etrop increases by 5.7%, likely driven by decreased Arctic LTS, indicating an increased coupling between Ftrop and the surface energy budget. The net impact of decreasing Ftrop and increasing efficiency is a positive 0.7 Wm–2 contribution to winter-season surface heating.

The electron content distribution of the north and south polar ionosphere is analyzed from 2001 to the beginning of 2019 from the Global Ionospheric Maps of VTEC computed each 15 minutes by UPC-IonSAT with a tomographic-Kriging combined technique. We have found the VTEC footprint of features previously reported by different authors and with different techniques: tongues of ionization, trough and dawn-side drifting structure, flux transfer event, Theta-aurora VTEC observation at SP, and Storm enhanced density (SED) during major geomagnetic storms. Moreover, by means of an unsupervised clustering algorithm (Learning Vector Quantization), we have characterized the main features of the ionospheric electron content climatology, separately for the north and south poles. In particular a mean Tongue Of Ionization (TOI) behaviour over south polar ionosphere during 1345UT-1945UT, from November to February, i.e. in local spring and summer seasons, is confirmed in agreement with recent findings.

Terrestrial water storage (TWS) plays a key role in land-surface interaction and the hydrological cycle. Changes in the variability of its components, including surface storage, soil moisture and groundwater can lead to significant changes in local climate, water supply sources and agricultural production. In this study, we assess the impacts of climate variability and change in surface and subsurface hydrological variables over the Magdalena-Cauca basin (Colombia) using a distributed conceptual hydrological model (WMF) driven by precipitation and temperature from four GCMs (general circulation models). WMF is calibrated using daily precipitation products from the Tropical Rainfall Measuring Mission (TRMM). Monthly mean anomalies of surface and groundwater storage outputs show consistency with Gravity Recovery and Climate Experiment (GRACE) data. Past (1970-2001) and future (2021-2050 and 2071-2100) precipitation from GCMs are statistically downscaled using a quantile mapping method to a spatial resolution of 0.25 by 0.25 degrees. Mean precipitation projections over the country are highly dependent on the selected GCMs, but the evidence shows agreement in a decrease towards the lower part of the basin; these projections are also present in surface runoff simulations. Annual mean streamflow follows the sign of the mean rainfall change over the basin. On the other hand, soil properties, topography, and geomorphological characteristics condition the patterns of subsurface and groundwater storage change (magnitude and localization), with the upper part of the Colombian Andes and the river mouth presenting the greatest changes. Results also show that mean soil moisture decrease in all scenarios, associated with changes in precipitation, but also due to the influence of temperature and evapotranspiration. The latter could lead to changes in the soil-atmosphere interaction, energetic conditions of the ecosystems and the need for agricultural mitigation strategies.

This paper examined the behavior of ionospheric irregularities over the African Equatorial Ionization Anomaly (EIA) during intense geomagnetic storms which occurred from 2012 to 2015. Total electron content (TEC) data was used to derive the rate of change of TEC index (ROTI). This was employed to monitor irregularities over the trough and crests of the EIA. Variations of the horizontal component of the Earth’s magnetic field (H) were examined. The H component was additionally used to compute ionospheric electric current disturbance (Diono). Prompt penetration electric field (PPEF) inferred from variations of Diono was compared with PPEF obtained from the Prompt Penetration Equatorial Electric Field Model (PPEFM). The PPEFM predicted accurately all PPEFs thus, was found to be valid over the African EIA. The local time of occurrence of interplanetary magnetic field (IMF ) dictated the behavior of irregularities. Eastward PPEF triggered short duration irregularities on 23 April 2012, 17 March 2013 and 20 February 2014 while westward disturbance dynamo electric field (DDEF) reduced them thereafter. During the storms recovery including the 15 July 2012 and 17 March 2015 events, irregularities were suppressed by westward DDEF. However, during the storms of 14 November 2012 and 29 June 2013 no irregularities were observed. Irregularities were always inhibited over the trough. The inhibition lasted longer during the super storm of March 2015. Over the crests, there were differences in their behavior on 16-17 July 2012, 15 November 2012 and 19 March 2013. These were however, not linked to storm-time electric field.

Over the past decades, Arctic sea ice has declined in thickness and extent and is shifting towards a seasonal ice regime, with accelerated ice drift and an increase in the seasonal ice zone. The changing Arctic ice cover will impact the trans-border exchange of sea ice between the Exclusive Economic Zones (EEZs) of the Arctic nations, with important implications for ice-rafted contaminant transport. To investigate projected changes to transnational ice exchange, we use the Lagrangian Ice Tracking System (LITS) to follow ice floes from the location of their formation to where they ultimately melt. We apply this tool to output from two ensembles of the Community Earth System Model (CESM): the CESM Large Ensemble, which uses a high emission scenario (RCP8.5) that leads to over 4°C global warming by 2100, and the CESM Low Warming ensemble, with reduced emissions that lead to a stabilized warming of 2°C by 2060. We also use the National Snow and Ice Data Center Polar Pathfinder and Climate Data Record products to evaluate the fidelity of the CESM present-day tracking simulations. Transnational ice exchange is well represented in CESM except for ice traveling from Russia to Norway, with twice as much ice following this pathway compared to observations. Initial results suggest this might be due to a combination of internal variability and speed biases in the observational data. The CESM projects that by mid-century, transnational ice exchange will expand, with a large increase in the fraction of transnational ice originating from Russia and the Central Arctic. As the seasonal ice zone grows, ice floes accelerate and transit times decrease, eventually cutting off ice exchange between longer pathways. By the end of the 21st century, we see a large impact of the emission scenario on ice exchange: consistent ice-free summers under the high emission scenario act to reduce the total fraction of transnational ice exchange compared to mid-century. The low emission scenario on the other hand continues to see an increase in transnational ice exchange by 2100. Under both scenarios, all pathways have decreased to average transit times of less than 2 years, compared to a maximum of 6 years under present-day conditions and 3 years by mid-century, effectively bringing the Arctic nations closer together.

While the geosciences are interdisciplinary in nature, they are not demographically diverse, which challenges the future viability and relevance of the geosciences. Causes and potential solutions for this deficiency have been proposed for several decades, but diversity within the geosciences has barely changed in that time. Dominant cultural, historical, and socioeconomic factors contribute to the lack of diversity and those factors only change slowly over generations. Solutions proposed for more immediate changes have been ineffective. Providing specific emotional support to those who are systemically non-dominant (SND) will be more impactful in improving diversity and inclusion within the geosciences. Specifically, we focus on intergroup emotions, which can be pleasant or unpleasant emotions that individuals feel due to their identification with one or more social groups. Using the Intergroup Emotions Theory, we argue that diversity and inclusion can be improved by helping those who are SND minimize undesirable emotions that arise when their group memberships are perceived to be negative. We end by making recommendations based on available research, yet we strongly call on the geoscience community to conduct further discipline-based research in this crucial area in the near future.

Oxygen first arose in Earth’s atmosphere 2.3 billion years ago, but geochemical evidence suggests that small pockets of oxygen may have arisen earlier than the atmospheric rise in oxygen. Cyanobacteria, a modern phylum of bacteria, are believed to have been the driving force behind the oxygenation of Earth’s atmosphere, and there are two basic hypotheses about how they caused this major geologic event. There is a hypothesis, called the ‘ecological’ hypothesis, that suggests cyanobacteria were unable to live in most environments initially, and thus we see the evidence for pockets of oxygen earlier than the atmospheric rise in oxygen. Specifically, the ‘ecological’ hypothesis says that cyanobacteria originally were unable to swim and couldn’t live in saline water, meaning seawater. However, the data for this only considers two possible states for the levels of salinity: freshwater and seawater. We used data from the literature and from experiments to show that the gradient of salinity matters to the ability of cyanobacteria to live in environments, and that we cannot say what salinity levels a cyanobacteria can tolerate based on where they were found alone. See supplemental file for full abstract.

For years the debate about the possible contamination of space and other planets with microbes from Earth has been a hot topic. Furthermore, the discovery of sulfate minerals on the Martian surface make this planet suitable to colonization by microorganisms adapted to survive and grow under earthly extreme conditions. One of these microorganisms is Desulfotalea psychrophila, a microbe able to generate cellular energy by means of an enzyme known as the dissimilatory sulfate reductase. As all bacterial enzymes are encoded within the bacterium nucleic acids, we have designed experiments to study the ability of this microbe to survive, grow and metabolize under simulated Martian conditions of pressure, temperature and different concentrations of sulfate compounds.

We investigate the Spectral Kurtosis (SK) statistical signature of a signal observed with the Robert C. Byrd Green Bank Telescope Breakthrough Listen back-end that was transmitted by the Voyager 1 spacecraft, which is up to date the only known artificial signal originating from outside our solar system, and we demonstrate the ability of the SK estimator to perform real-time detection and discrimination against natural astronomical transients of deep-space Voyager 1-like technological signatures of alien origin. We use the same approach to investigate the yet controversial nature of the FRB 180301 signal detected during the Breakthrough Listen observations with the Parkes telescope.

A radio transmitter which is accelerating with a non-zero radial component with respect to a receiver will produce a signal that appears to change in frequency over time. This effect, commonly produced in astrophysical situations where orbital and rotational motions are ubiquitous, is called a drift rate. In radio SETI (Search for Extraterrestrial Intelligence) research, it is unknown a priori which frequency a signal is being sent at, or even if there will be any drift rate at all besides motions in the solar system. Therefore a range of potential drift rates need to be individually searched, and a maximum drift rate needs to be chosen. The middle of this range is zero, indicating no acceleration, but the absolute value for the limits remains unconstrained. A balance must be struck between computational time and the possibility of excluding a signal from ETI. In this work, we examine physical considerations that constrain a maximum drift rate and highlight the importance of this problem in any narrowband SETI search. We determine that a normalized drift rate of 200 nHz (e.g. 200 Hz/s at 1 GHz) is a generous, physically motivated guideline for the maximum drift rate that should be applied to future narrowband SETI projects if computational capabilities permit.

Venus is commonly known as the beautiful Evening Star of the night sky. Despite its bulk composition and size being similar (Interior ESI 0.98) to those of Earth, Venus is an extremely hot and dry planet, with temperatures ranging from 630 - 740K. With the current physical conditions, a potential areal biosphere could exist on the sulphuric acid-dominated clouds, providing moderate temperatures and pressures due to high altitudes. A theorised Iron or Sulphur metabolism could support exotic life in these extremely acidic (pH 0) conditions. The past habitability for regular life could be connected to the present habitability for exotic life through possible evolution, extending the possible Habitability timeline. Due to its smaller orbital distance (0.7 AU), Venus could have been the first habitable planet in the solar system, with optimistic models showing that Venus may have had a complex atmosphere and a liquid ocean for around 2 billion years, before the moist runaway greenhouse effect transformed the planet. High values for the D/H ratio and carbon abundance, combined with Venus’s slow rotation rate indicate the potential for biological life developing in Past Venus’s possible Earth-like conditions. These models were analysed from a perspective of Habitability, along with probable evolution into the present exotic life.