sedInterFoam 1.0: a three-phase numerical model for sediment transport applications with free surfaces
Antoine Mathieu, Yeulwoo Kim, Tian-Jian Hsu, Cyrille Bonamy, and Julien Chauchat
Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2024-16,2024
Preprint under review for GMD (discussion: open, 0 comments)
Most of the tools available to model sediment transport do not account for complex physical mechanisms such as surface wave driven processes. In this study, a new model sedInterFoam allows to reproduce numerically complex configurations to investigate coastal sediment transport applications dominated by surface waves and gain insight into the complex physical processes associated with breaking waves and morphodynamics.
Impact of horizontal resolution and model time step on European precipitation extremes in the OpenIFS 43r3 atmosphere model
Yingxue Liu, Joakim Kjellsson, Abhishek Savita, and Wonsun Park
Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2024-66,2024
Preprint under review for GMD (discussion: open, 0 comments)
The impact of horizontal resolution and model time step on extreme precipitation over Europe is examined in OpenIFS. We find that the biases are reduced with increasing horizontal resolution, but not with reducing time step. The large-scale precipitation is more sensitive to the horizontal resolution, however, the convective precipitation is more sensitive to the model time step. Increasing horizontal resolution is more important for extreme precipitation simulation that reducing time step.
A software model of Earth, meant to simulate and monitor environmental hazards while finding ways to mitigate climate change, began its monitoring and predictive mission on Monday, the EU Commission said.
A new study conducted by IIASA researchers and their colleagues highlights that cooperation in infrastructure operation between countries surrounding the Lancang-Mekong River Basin could bring major economic and environmental co-benefits.
When comparing model simulations of Earth's recent warming to real-world observations, differences can arise from several factors, including model errors in the simulated response to increased greenhouse gases and natural fluctuations within the climate system.
Timothy Lang is a co-author on an article titled "Employing Optical Lightning Data to identify lightning flashes associated to Terrestrial Gamma-ray Flashes," which was published in the Bulletin of Atmospheric Science and Technology.
Known for its glowing swaths of yellow, orange and red, the U.S. Drought Monitor has warned farmers, residents and officials throughout the nation of impending water scarcity every week since 1999.
A new research commentary led by Griffith University researchers highlights inequities between downstream and upstream countries that share the same watershed. The paper, "The Global Biodiversity Framework can be leveraged to better manage transboundary watersheds," has been published in PNAS.
The first microwave and submillimetre closure study using particle models of oriented ice hydrometeors to simulate polarimetric measurements of ice clouds
Karina McCusker, Anthony J. Baran, Chris Westbrook, Stuart Fox, Patrick Eriksson, Richard Cotton, Julien Delanoë, and Florian Ewald
Atmos. Meas. Tech., 17, 3533–3552, https://doi.org/10.5194/amt-17-3533-2024, 2024
Polarised radiative transfer simulations are performed using an atmospheric model based on in situ measurements. These are compared to large polarisation measurements to explore whether such measurements can provide information on cloud ice, e.g. particle shape and orientation. We find that using oriented particle models with shapes based on imagery generally allows for accurate simulations. However, results are sensitive to shape assumptions such as the choice of single crystals or aggregates.
High Spectral Resolution Lidar – generation 2 (HSRL-2) retrievals of ocean surface wind speed: methodology and evaluation
Sanja Dmitrovic, Johnathan W. Hair, Brian L. Collister, Ewan Crosbie, Marta A. Fenn, Richard A. Ferrare, David B. Harper, Chris A. Hostetler, Yongxiang Hu, John A. Reagan, Claire E. Robinson, Shane T. Seaman, Taylor J. Shingler, Kenneth L. Thornhill, Holger Vömel, Xubin Zeng, and Armin Sorooshian
Atmos. Meas. Tech., 17, 3515–3532, https://doi.org/10.5194/amt-17-3515-2024, 2024
This study introduces and evaluates a new ocean surface wind speed product from the NASA Langley Research Center (LARC) airborne High-Spectral-Resolution Lidar – Generation 2 (HSRL-2) during the NASA ACTIVATE mission. We show that HSRL-2 surface wind speed data are accurate when compared to ground-truth dropsonde measurements. Therefore, the HSRL-2 instrument is able obtain accurate, high-resolution surface wind speed data in airborne field campaigns.
On the importance of middle-atmosphere observations on ionospheric dynamics using WACCM-X and SAMI3
Fabrizio Sassi, Angeline G. Burrell, Sarah E. McDonald, Jennifer L. Tate, and John P. McCormack
Ann. Geophys., 42, 255–269, https://doi.org/10.5194/angeo-42-255-2024, 2024
This study shows how middle-atmospheric data (starting at 40 km) affect day-to-day ionospheric variability. We do this by using lower atmospheric measurements that include and exclude the middle atmosphere in a coupled ionosphere–thermosphere model. Comparing the two simulations reveals differences in two thermosphere–ionosphere coupling mechanisms. Additionally, comparison against observations showed that including the middle-atmospheric data improved the resulting ionosphere.
Author(s): F. Garcia-Rubio, V. Tranchant, E. C. Hansen, A. Reyes, R. Tabassum, H. U. Rahman, P. Ney, E. Ruskov, and P. Tzeferacos
The temporal evolution of weak shocks in radiative media is theoretically investigated in this work. The structure of radiative shocks has traditionally been studied in a stationary framework. Their systematic classification is complex because layers of optically thick and thin regions alternate to …
[Phys. Rev. E 109, 065206] Published Mon Jun 10, 2024
Author(s): Takumi Morino, Machiko Ode, and Shoichi Hirosawa
We formulated two phase-field models to compute interfacial compositions, characterized by their high computational accuracy and efficiency. The inaugural model utilizes convergence calculations to fulfill the equal diffusion potential condition, while the subsequent model obviates the need for such…
[Phys. Rev. E 109, 065303] Published Mon Jun 10, 2024
Abstract
Medium-scale traveling ionospheric disturbances (MSTIDs) can significantly alter a region's ionosphere features, severely impacting the performance and stability of services such as shortwave communication and navigation positioning. By utilizing the total electron content (TEC) data from BeiDou geostationary satellites for 2022–2023, this study investigated the characteristics of MSTIDs over Hong Kong concerning local time and seasons. A total of 622 MSTID events were observed, classified into three types: daytime (10:00–17:00 LT), twilight (17:00–22:00 LT), and nighttime (22:00–02:00 LT). The occurrence rates and excitation mechanisms of the three types of MSTIDs were analyzed. Daytime and twilight MSTIDs had higher occurrence rates during winter, while nighttime MSTIDs had higher occurrence rates in summer and were even absent during winter. Overall, daytime MSTIDs were the most common, followed by twilight MSTIDs, while nighttime MSTIDs were less frequent. The propagation directions of MSTIDs exhibited anisotropy but showed some clustering patterns. Daytime MSTIDs exhibited high directional diversity during summer, but more concentrated in winter. Nighttime MSTIDs, on the other hand, were more focused during summer. It is worth noting that twilight MSTIDs exhibit similar climatological characteristics to daytime MSTIDs, which have not been observed in previous studies. It is suggested that daytime MSTIDs in the Hong Kong region are likely primarily generated by atmospheric gravity waves (AGWs) from low-latitude regions, while nighttime MSTIDs are likely caused by Perkins instability. Twilight MSTIDs may originate from AGWs at the solar terminator, as well as daytime MSTIDs propagated from mid-latitude areas.
Abstract
Fault regions inferred to be slowly slipping are interpreted to accommodate much of tectonic plate motion aseismically and potentially serve as barriers to earthquake rupture. Here, we build on prior work using simulations of earthquake sequences with enhanced dynamic fault weakening to show how fault regions that exhibit decades of steady creep or transient slow-slip events can be driven to dynamically fail by incoming earthquake ruptures. Following substantial earthquake slip, such regions can be under-stressed and locked for centuries prior to slowly slipping again. Our simulations illustrate that slow fault slip indicates that a region is sufficiently loaded to be failing about its quasi-static strength. Hence, if a fault region is susceptible to failing dynamically, then observations of slow slip could serve as an indication that the region is critically stressed and ready to fail in a future earthquake, posing a qualitatively different interpretation of slow slip for seismic hazard.
Abstract
Applying machine learning to continuous acoustic emissions, signals previously deemed noise, from laboratory faults and slowly slipping subduction-zone faults, demonstrates hidden signatures are emitted that describe physical details, including fault displacement and friction. However, no evidence currently exists to demonstrate that similar hidden signals occur during seismogenic stick-slip on earthquake faults—the damaging earthquakes of most societal interest. We show that continuous seismic emissions emitted during the 2018 multi-month caldera collapse sequence at the Kı̄lauea volcano in Hawai'i contain hidden signatures characterizing the earthquake cycle. Multi-spectral data features extracted from 30 s intervals of the continuous seismic emission are used to train a gradient boosted tree regression model to predict the GNSS-derived contemporaneous surface displacement and time-to-failure of the upcoming collapse event. This striking result suggests that at least some faults emit such signals and provide a potential path to characterizing the instantaneous and future behavior of earthquake faults.
Abstract
The El Niño-Southern Oscillation causes anomalous atmospheric circulation, temperature and precipitation across southern polar latitudes, but the influence of Central and Eastern Pacific El Niño events on Antarctic surface mass balance and snow accumulation has not yet been assessed. Here, we use reanalysis and reanalysis-forced regional climate model output and find that Central Pacific El Niño results in significantly increased snow accumulation in the western Ross Sea sector and significantly decreased snow accumulation in the Amundsen Sea sector. Eastern Pacific El Niño is associated with similar but weaker patterns, with some regional exceptions. In some areas, like Dronning Maud Land, or the Wilkes Subglacial Basin, the effect of El Niño on snow accumulation changes from increased to reduced accumulation depending on the type of El Niño. Our results show that projecting El Niño types is important for constraining future changes in Antarctic surface mass balance.
Abstract
The sediment mixed layer (SML) in the deep ocean is an important interface with a rich diversity of benthic organisms. With increasing ocean mineral exploration, and eventual mining, the effect of sediment mixing on deep ocean ecosystems has raised considerable concern. We evaluate the distribution patterns and driving factors of SML depth in deep ocean nodule fields using naturally occurring 210Pb–226Ra isotopes. Results show that average SML depth has increased in Mn-nodule fields since the end of the last century. SML processes are associated with significant desorption of 226Ra from sediments, resulting in a departure from radioactive equilibrium. By estimating possible driving factors, we conclude that anthropogenic exploration activities, rather than natural physical and/or biological drivers, are the most likely mechanism for intensified sediment mixing. 210Pb–226Ra disequilibria may be a potential tracer for quantifying the impact of human exploration on deep-ocean sediment mixing and associated biological and geochemical effects.
Abstract
A mini-neutron monitor (MNM) was installed at the German Antarctic Neumayer III station, measuring the variation of galactic cosmic rays and searching for Forbush Decreases (FDs) caused by solar activities. Running continuously from 2014 until the end of 2017, the long-term stability of the detector could be investigated. After correcting the air pressure and normalization to the 27 days running mean averages of the SANAE and TERA Neutron Monitors (NMs), the daily running mean count rates are compared with the SANAE and TERA NMs also installed in Antarctica. For most of the 14 FDs with magnitudes greater than 3, taken from the list compiled by the IZMIRAN group (http://spaceweather.izmiran.ru/eng/dbs.html), the three detectors show consistent particle flux variation, although the average rate of the MNM is more than a hundred times smaller. The light and low-cost MNM is an ideal alternative to heavy and old NMs, especially at high altitudes and remote environments.
Abstract
In this paper, we study Titan's magnetotail using Cassini data from the T122-T126 flybys. These consecutive flybys had a similar flyby geometry and occurred at similar Saturn magnetospheric conditions, enabling an analysis of the magnetotail's structure. Using measurements from Cassini's magnetometer (MAG) and Radio and Plasma Wave System/Langmuir probe (RPWS/LP) we identify several features consistent with reported findings from earlier flybys, for example, T9, T63 and T75. We find that the so-called ’split’ signature of the magnetotail becomes more prominent at distances of at least 3,260 km (1.3 R
T
) downstream of Titan. We also identify a specific signature of the sub-alfvenic interaction of Titan with Saturn, the Alfvén wings, which are observed during the T123 and T124 flyby. A coordinate transformation is applied to mitigate variations in the upstream magnetic field, and all the flybys are projected into a new reference frame—aligned to the background magnetic field reference frame (BFA). We show that Titan's magnetotail is confined to a narrow region of around ∼4 R
T
Y
BFA
. Finally, we analyze the general draping pattern in Titan's magnetotail throughout the TA to T126 flybys.
