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European Geosciences Union

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Novel oxalate-carbonate pathways identified in the tropical dry evergreen forest of Tamil Nadu, India

The oxalate-carbonate pathway, where trees and microbes store inorganic carbon as minerals, was studied on four tree species of the threatened tropical dry evergreen forest Indian forest. We used high-throughput sequencing of a gene to detect oxalate-degrading microbes. For all tree species, produced oxalate led to carbonate formation in soils and on wood. This carbon may be leached into water, suggesting a hidden source of inorganic carbon with implications for climate and conservation.

The frosty frontier: redefining the mid-latitude tropopause using the relative humidity over ice

We present a new technique to determine the tropopause based on the gradient of relative humidity over ice. This approach captures the character of the tropopause remarkably well, both in individual vertical profiles and in long-term averages, providing a consistent and physically meaningful representation of the transition between the troposphere and the stratosphere.

Recent history and future demise of Jostedalsbreen, the largest ice cap in mainland Europe

We model the historical and future evolution of the Jostedalsbreen ice cap in Norway, projecting substantial and largely irreversible mass loss for the 21st century, and that the ice cap will split into three parts. Further mass loss is in the pipeline, with a disappearance during the 22nd century under high emissions. Our study demonstrates an approach to model complex ice masses, highlights uncertainties due to precipitation, and calls for further research on long-term future glacier change.

An adaptable DTS-based parametric method to probe near-surface vertical temperature profiles at millimeter resolution

We present the the Fine Resolution Adaptable Distributed Temperature Sensing (FRADTS) method, which allows for mm-resolution probing of vertical temperature profiles, using coil-based distributed temperature sensing. The method is fully open source and parametric, such that unique field setups can be generated and reproduced. The method is extensively tested within a ~10cm grass canopy in a field campaign.

The TropoPause Composition TOwed Sensor Shuttle (TPC-TOSS): a new airborne dual platform approach for atmospheric composition measurements at the tropopause

Deployed on a Learjet as a tandem measurement platform during the TPEx I (TropoPause composition gradients and mixing Experiment) campaign in June 2024, the new TPC-TOSS (TropoPause Composition Towed Sensor Shuttle) system delivers high-resolution in situ data on ozone, aerosol, and key meteorological parameters. Laboratory and in-flight tests confirmed its precision and stability. Observed gradients near the tropopause reveal active mixing and transport processes in the tropopause region.

A statistical study of the O₂ atmospheric band aurora observed by the Swedish satellite MATS

This study uses images taken by the Swedish satellite MATS (Mesospheric Airglow Tomography and Spectroscopy) to conduct a statistical analysis of the molecular oxygen atmospheric band emissions in the aurora. This auroral emission can not be observed from the ground, making it one of the least understood auroral emissions. Our results provide a new dataset with information on the peak altitude, geomagnetic location, and auroral intensity of 378 events detected between February and April 2023.

IASI global radiometric uncertainty budget

This study establishes the global radiometric uncertainty budget of the Infrared Atmospheric Sounder Interferometer (IASI) instruments onboard Eumetsat first generation MetOp satellites. Major contributions to the budget arise from the correction of the analog non-linearity, the black body characterization, the scan mirror reflectivity and the background radiance instability. The estimated uncertainty remains relatively stable throughout the lifetime of the instruments.

The airborne chicago water isotope spectrometer: an integrated cavity output spectrometer for measurements of the HDO ∕ H₂O isotopic ratio in the Asian Summer Monsoon

The water molecule comes in several different varieties, which are nearly indistinguishable in daily life. However, slight differences between the water molecule types can be exploited to achieve better scientific understanding of parts of Earth's atmosphere. In this work we describe the design, construction, and operation of an instrument meant to measure these molecules aboard research aircraft up to altitudes of 20 km.

Progressive destabilization of a freestanding rock pillar in permafrost on the Matterhorn (Swiss Alps): Hydro-mechanical modeling and analysis

On 13 June 2023, a freestanding rock pillar on the Matterhorn collapsed after years of weakening. Our study examines this progressive destabilization by analyzing field data and integrating lab experiments into a hydro-mechanical model. We highlight the critical role of water infiltration into frozen rock, intensified by climate warming, as a widespread driver of the rising frequency of rockfalls in high mountain permafrost regions.

Reviews and syntheses: Artisanal and small-scale gold mining (ASGM)-derived mercury contamination in agricultural systems: what we know and need to know

Artisanal & Small-scale Gold Mining (ASGM) is rapidly expanding and mercury-use in the sector impacts agricultural systems near these spatially distributed activities. Mercury from ASGM is taken up by crops from both (1) air and (2) soil/water. Mercury in crops can also be passed to humans directly (eating crops) or via livestock/poultry after eating crops. Research in this area requires interdisciplinary, collaborative, and adaptable approaches to improve our comprehension of these impacts.

Drivers and impacts of westerly moisture transport events in East Africa

Anomalous westerly winds bring moisture into East Africa, increasing precipitation in the region. Using the first spatially unconstrained framework to detect this circulation and associated precipitation, we show westerlies contribute up to 60% of rainfall in Tanzania in January and February, and are more likely when the Madden Julian Oscillation and/or tropical cyclones are active over the Indian Ocean. This work highlights the complex interactions driving regional precipitation variability.

Automated mask generation in citizen science smartphone photos and their value for mapping plant species in drone imagery

We introduce an automated approach for generating segmentation masks for citizen science plant photos, making them applicable to computer vision models. This framework effectively transforms citizen science data into a data treasure for segmentation models for plant species identification in aerial imagery. Using automatically labeled photos, we train segmentation models for mapping tree species in drone imagery, showcasing their potential for forestry, agriculture, and biodiversity monitoring.

Observed and modeled Arctic airmass transformations during warm air intrusions and cold air outbreaks

Aircraft observations of air parcels moving into and out of the Arctic are reported. From the data, heating and cooling as well as drying and moistening of the air masses along their way into and out of the Arctic could be measured for the first time. These data are used to evaluate if weather prediction models are able to accurately represent these air mass transformations. This work helps to model the future Arctic climate changes, which may have an impact for mid-latitude weather as well.

Reviews and syntheses: Best practices for the application of marine GDGTs as proxy for paleotemperatures: sampling, processing, analyses, interpretation, and archiving protocols

Many academic laboratories worldwide process environmental samples for analysis of membrane lipid molecules of archaea, for the reconstruction of past environmental conditions. However, the sample workup scheme involves many steps, each of which has a risk of contamination or bias, affecting the results. This paper reviews steps involved in sampling, extraction and analysis of lipids, interpretation and archiving of the data. This ensures reproducible, reusable, comparable and consistent data.

Holocene land cover change in North America: continental trends, regional drivers, and implications for vegetation–atmosphere feedbacks

Holocene vegetation–atmosphere interactions provide insight into intensifying land use impacts and the Holocene Conundrum: a mismatch between data- and model-inferred temperature. Using pollen records and statistical modeling, we reconstruct Holocene land cover for North America. We determine patterns and magnitudes of land cover changes across scales. We attribute land cover changes to ecological, climatic, and human drivers. These reconstructions provide benchmarks for Earth system models.

Milankovitch theory “as an initial value problem”: Implications of the long memory of ice advection

We describe a so far unrecognized physical phenomenon of orbital forcing modifying the terrestrial physics in such a way that instead of erasing the memory of initial conditions this memory is extended and initial values become major governing parameters.

Estimates of Atlantic meridional heat transport from spatiotemporal fusion of Argo, altimetry, and gravimetry data

Understanding how heat moves through the ocean is crucial to predicting future climate change confidently. This requires accurate records of heat transport throughout the ocean, but these are challenging to obtain by direct ocean observation. Here, we combine in situ and satellite-based observations to generate estimates of meridional heat transport for the period 2004–2020 at 3-month resolution across the Atlantic Ocean with improved accuracy compared to existing indirectly inferred estimates.

Global and regional sea-surface temperature changes over the Marine Isotopic Stage 9e and Termination IV

To better understand climate change in past warm periods, we studied global ocean temperature during an interglacial period about 330,000 years ago. Combining 98 records on common timeline, we found regional differences in the timing and amplitude of changes, which smoothed the global signal. We also show that the deglacial warming rate was about three times lower than today's global warming rate.

Formation of mega-scale glacial lineations far inland beneath the onset of the Northeast Greenland Ice Stream

The subglacial landforms beneath actively fast-flowing ice in Greenland have not been explored in detail, as digital elevation models have not had a high enough resolution to see these features. We use swath radar imaging to visualise landforms at the onset of an ice stream, revealing mega-scale glacial lineations, that would usually be assumed to be indicative of faster ice flow than the current velocities. Interpretation of the landscape also gives an indication of the properties of the bed.

Properties of large-amplitude kilometer-scale field-aligned currents at auroral latitudes, as derived from Swarm satellites

By using magnetic field recordings sampled at 50 Hz by Swarm A and C satellites around the quasi-coplanar orbit configuration, near 1 October 2021, we investigate the properties of kilometer-scale field-aligned currents (FACs) at auroral latitudes. The kilometer-scale (0.2-5 km) FACs exhibit short-lived (<1 s) randomly appearing large current density spikes (partly exceeding 100 µA m-2). Preferred occurrences are the noon to prenoon (nightside to dusk) sector around 80° (70°) MLat, respectively.