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1866 items found

10 20 50

First observations of continuum emission in dayside aurora

We studied the first broad band emissions, called continuum, in the dayside aurora. They are similar to Strong Thermal Emission Velocity Enhancement (STEVE) with white-, pale-pink-, or mauve-coloured light. But unlike STEVE, they follow the dayside aurora forming rays and other dynamic shapes. We used ground optical and radar observations and found evidence of heating and upwelling of both plasma and neutral air. This study provides new information on conditions for continuum emission, but its understanding will require further work.

Is drought protection possible without compromising flood protection? Estimating the potential dual-use benefit of small flood reservoirs in southern Germany

In this paper, we use models to demonstrate that even small flood reservoirs – which capture water to avoid floods downstream – can be repurposed to release water in drier conditions without affecting their ability to protect against floods. By capturing water and releasing it once levels are low, we show that reservoirs can greatly increase the water available in drought. Having more water available to the reservoir, however, is not necessarily better for drought protection.

Qualitative risk assessment of sensitive infrastructures at the local level: flooding and heavy rainfall

Natural Hazards and Earth System Sciences
DOI 10.5194/nhess-25-2097-2025
4 July 2025

In post-disaster reconstruction, emphasis should be placed on critical and sensitive infrastructures. In Germany, as in other countries, sensitive infrastructures have not yet been focused on; therefore, we developed a method for determining the risk that sensitive infrastructures are facing in the context of riverine and pluvial flooding. The easy-to-use assessment framework can be applied to various sensitive infrastructures, e.g., to qualify and accelerate decisions in the reconstruction process.

Phylogeochemistry: exploring evolutionary constraints on belemnite rostrum element composition

Belemnite rostrum geochemistry is used as a proxy in palaeoceanography. Evolutionary patterns in element ratios (Mg/Ca, Sr/Ca, Mn/Ca, and Fe/Ca) from belemnite rostra based on a literature dataset are assessed. These proxy data reflect a complex interplay between evolutionary, ontogenetic, environmental, kinetic, and diagenetic effects. We coin the new term “phylogeochemistry” for this interdisciplinary research field.

The satellite chlorophyll signature of Lagrangian eddy trapping varies regionally and seasonally within a subtropical gyre

Eddies are rotating ocean vortices up to hundreds of kilometers in diameter that stimulate phytoplankton blooms. We used satellite data and simulations of currents to examine the effect of eddy trapping strength on phytoplankton concentration in the open North Pacific Ocean. Coherent eddies trap phytoplankton, while "leaky" ones have lower concentrations because they mix with surrounding waters. However, contrary to previous theory, eddy-trapped blooms are more prominent in southern latitudes.

Long-term prediction of the Gulf Stream meander using OceanNet: a principled neural-operator-based digital twin

The Gulf Stream is a prominent oceanic feature in the northwestern Atlantic Ocean that influences weather patterns in the Northern Hemisphere and is notoriously difficult to predict. We present a machine learning model, OceanNet, to predict the position of the Gulf Stream months in advance. OceanNet is able to perform a 120 d prediction 4 000 000 times faster than traditional methods of ocean modeling with great accuracy.

Using 3D observations with high spatio-temporal resolution to calibrate and evaluate a process-focused cellular automaton model of soil erosion by water

SOIL
DOI 10.5194/soil-11-413-2025
16 June 2025

This study develops a new method to improve the calibration and evaluation of models that predict soil erosion by water. By using advanced imaging techniques, we can capture detailed changes in the soil surface over time. This helps improve models that forecast erosion, especially as climate change creates new and unpredictable conditions. Our findings highlight the need for more precise tools to better model erosion of our land and environment in the future.

The potential of observing atmospheric rivers with Global Navigation Satellite System (GNSS) radio occultation

The study investigates using Global Navigation Satellite System Radio Occultation (GNSS-RO) to analyze the vertical structure of humidity in atmospheric rivers (ARs). Specific humidity and integrated water vapor from the COSMIC Data Analysis and Archive Center (CDAAC) and the Wegener Center (WEGC) are compared with the Special Sensor Microwave Imager/Sounder (SSMIS), showing that GNSS-RO adds vertically resolved data. Despite a slight low bias, combining GNSS-RO and SSMIS improves AR analysis.

Implications of reduced-complexity aerosol thermodynamics on organic aerosol mass concentration and composition over North America

We implemented the BAT-VBS (Binary Activity Thermodynamics volatility basis set) aerosol thermodynamics model in the GEOS-Chem chemical transport model to efficiently account for organic aerosol water uptake, nonideal mixing, and impacts on the gas–particle partitioning of semi-volatile organics. Compared to GEOS-Chem's complex (dry) scheme, we show that the BAT-VBS model can predict substantial enhancements in organic aerosol mass concentration at moderate-to-high relative humidity.

GC Insights: Consistency in pyrocartography starts with color

Fire progression maps (FPMs) provide information regarding wildland fire spread (progress) through time to broad audiences. However, information regarding the best use of color to denote fire progression via maps is limited. This can potentially limit a map's ability to effectively communicate information by creating inconsistent messaging and accessibility challenges. Here, I provide color map recommendations to open a discussion towards consistent and accessible fire progression mapping.

Leaping and vortex motion of the shock aurora toward the late evening sector observed on 26 February 2023

Our research explores the shock aurora, which is typically observed on the dayside due to the rapid compression of the Earth's magnetic field. We observed this rare aurora on the nightside, a region where such events are difficult to detect. Using ground-based cameras, we identified new features, including leaping and vortex-like patterns. These findings offer a fresh insight into the interactions between the solar wind and the magnetosphere, enhancing our understanding of space weather and its effects.

Sedimentary ancient DNA insights into foraminiferal diversity near the grounding line in the western Ross Sea, Antarctica

Ancient foraminiferal DNA is studied in five Antarctic cores with sediments up to 25 kyr old. We use a standard and a new, more effective marker, which may become the next standard for paleoenvironmental studies. Much less diverse foraminifera occur on slopes of submarine moraines than in open-marine settings. Soft-walled foraminifera, not found in the fossil record, are especially abundant. There is no foraminiferal DNA in tills, suggesting its destruction during glacial redeposition.

Explaining the period fluctuation of the quasi-biennial oscillation

The paper addresses a fundamental but unresolved question about the tropical stratospheric wind oscillation: why does the period of the oscillation fluctuate irregularly? We use global reanalysis data to provide evidence that the oscillation period is primarily modulated by seasonal variations in small-scale atmospheric wave activity. The findings have implications for seasonal and climate predictions.

Mean ocean temperature change and decomposition of the benthic δ¹⁸O record over the past 4.5 million years

We reconstruct changes in mean ocean temperature (ΔMOT) over the last 4.5 Myr. We find that the ratio of ΔMOT to changes in global mean sea surface temperature was around 0.5 before the Middle Pleistocene transition but was 1 thereafter. We subtract our ΔMOT reconstruction from the global δ18O record to derive the δ18O of seawater. Finally, we develop a theoretical understanding of why the ratio of ΔMOT / ΔGMSST changed over the Plio-Pleistocene.

Quantified ice-nucleating ability of AgI-containing seeding particles in natural clouds

We analyzed the ability of silver iodide particles (a commonly used cloud-seeding agent) to form ice crystals in naturally occurring liquid clouds at −5 to −8 °C and found that only ≈ 0.1 %−1 % of particles nucleate ice, with a negative dependence on temperature. By contextualizing our results with previous laboratory studies, we help to bridge the gap between laboratory and field experiments, which also helps to inform future cloud-seeding projects.

Calcium is associated with specific soil organic carbon decomposition products

SOIL
DOI 10.5194/soil-11-381-2025
20 May 2025

This study shows that calcium (Ca) preserves soil organic carbon (SOC) in acidic soils, challenging beliefs that their interactions were limited to near-neutral or alkaline soils. Using spectromicroscopy, we found that Ca was co-located with a specific fraction of carbon, rich in aromatic and phenolic groups. This association was disrupted when Ca was removed but was reformed during decomposition with added Ca. Overall, this suggests that Ca amendments could enhance SOC stability.

Multifractality of climate networks

We have developed a systematic approach to study the climate system at multiple scales using climate networks, which have been previously used to study correlations between time series in space at only a single scale. This new approach is used to upscale precipitation climate networks to study the Indian summer monsoon and to analyze strong dependencies between spatial regions, which change with changing scales.

Social sensing a volcanic eruption: application to Kīlauea, 2018

Natural Hazards and Earth System Sciences
DOI 10.5194/nhess-25-1681-2025
13 May 2025

Protecting lives and livelihoods during volcanic eruptions is the key challenge in volcanology. Analysing social media usage during volcanic crises can help us better understand the impacts of volcanic eruptions and how warning messages are received and actioned, to eventually better protect those people and their livelihoods. Our work shows how social media data could be used in real time during a volcanic crisis to learn more about volcanic eruptions.

Surficial sediment remobilization by shear between sediment and water above tsunamigenic megathrust ruptures: experimental study

We propose a new mechanism of co-seismic sediment entrainment induced by shear stress at the sediment–water interface during major subduction earthquakes rupturing to the trench. Physical experiments show that flow velocities consistent with long-period earthquake motions can entrain synthetic marine sediment, and high-frequency vertical shaking can enhance this mobilization. They validate the proposed entrainment mechanism, which opens new avenues for paleoseismology in deep-sea environments.

Cold-water coral mounds are effective carbon sinks in the western Mediterranean Sea

Cold-water coral mounds are large structures on the seabed that are built by corals over thousands of years. They are regarded as carbonate sinks, with a potentially important role in the marine carbon cycle, but more quantitative studies are needed. Using sediment cores, we calculate the amount of carbon that has been stored in two mounds over the last 400 000 years. We provide the first numbers and show that up to 19 times more carbon is accumulated in mounds than on the common seafloor.