Abstract
Equatorial Plasma Bubbles (EPBs) can generate ionospheric scintillation at GHz frequencies used in the Global Navigation Satellite System (GNSS). Emerging at any longitude following sunset and typically moving eastward, monitoring the EPBs is essential for space weather services. Using three GNSS receivers positioned at the same latitude (∼0°N) but separated in longitudes (∼9°, ∼16°, and ∼25°) and the 47 MHz Equatorial Atmosphere Radar (EAR) in Indonesia, our study delineates the zonal extent of eastward-traveling post-sunset EPB inducing ionospheric GNSS scintillation. Typically, the scintillation occurrences detected by a ground receiver concentrate between 19 and 01 local time (LT), with a peak incidence observed at 21 LT. Furthermore, an experiment combining EAR observations with GNSS receiver data allowed for the determination of the linear change in the speed of eastward-traveling EPB inducing scintillation during this time period. Interestingly, the longitudinal range of eastward-traveling EPBs increased with higher solar flux (F10.7) levels. Our findings suggest that EPB can induce scintillation up to a longitudinal distance of approximately 25° from the onset location at sunset to the eastern midnight region, particularly in F10.7 ranging from 90 to 150 solar flux units. Moreover, experiments using longitudinally separated GNSS receivers indicated that scintillations during 19–01 LT originate from post-sunset EPBs within a longitudinal range extending 25° to the west. In conclusion, our research provides valuable insight into the ability of eastward-traveling EPB to induce GNSS scintillation within a longitudinal range of 25°, thereby enhancing EPB and scintillation monitoring and prediction in regional space weather services.
Numerical stabilization methods for level-set-based ice front migration
Gong Cheng, Mathieu Morlighem, and G. Hilmar Gudmundsson
Geosci. Model Dev., 17, 6227–6247, https://doi.org/10.5194/gmd-17-6227-2024, 2024
We conducted a comprehensive analysis of the stabilization and reinitialization techniques currently employed in ISSM and Úa for solving level-set equations, specifically those related to the dynamic representation of moving ice fronts within numerical ice sheet models. Our results demonstrate that the streamline upwind Petrov–Galerkin (SUPG) method outperforms the other approaches. We found that excessively frequent reinitialization can lead to exceptionally high errors in simulations.
RCEMIP-II: mock-Walker simulations as phase II of the radiative–convective equilibrium model intercomparison project
Allison A. Wing, Levi G. Silvers, and Kevin A. Reed
Geosci. Model Dev., 17, 6195–6225, https://doi.org/10.5194/gmd-17-6195-2024, 2024
This paper presents the experimental design for a model intercomparison project to study tropical clouds and climate. It is a follow-up from a prior project that used a simplified framework for tropical climate. The new project adds one new component – a specified pattern of sea surface temperatures as the lower boundary condition. We provide example results from one cloud-resolving model and one global climate model and test the sensitivity to the experimental parameters.
Quantifying the role of ozone-caused damage to vegetation in the Earth system: a new parameterization scheme for photosynthetic and stomatal responses
Fang Li, Zhimin Zhou, Samuel Levis, Stephen Sitch, Felicity Hayes, Zhaozhong Feng, Peter B. Reich, Zhiyi Zhao, and Yanqing Zhou
Geosci. Model Dev., 17, 6173–6193, https://doi.org/10.5194/gmd-17-6173-2024, 2024
A new scheme is developed to model the surface ozone damage to vegetation in regional and global process-based models. Based on 4210 data points from ozone experiments, it accurately reproduces statistically significant linear or nonlinear photosynthetic and stomatal responses to ozone in observations for all vegetation types. It also enables models to implicitly capture the variability in plant ozone tolerance and the shift among species within a vegetation type.
PIBM 1.0: An individual-based model for simulating phytoplankton acclimation, diversity, and evolution in the ocean
Iria Sala and Bingzhang Chen
Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2024-130,2024
Preprint under review for GMD (discussion: open, 0 comments)
Phytoplankton, tiny photosynthetic organisms, produce nearly half of Earth's oxygen. To analyze their physiology, diversity, and evolution in the ocean, we developed a model that treats phytoplankton as individual particles. Moreover, our model considers phytoplankton size, temperature, and light traits, and allows for mutations in phytoplankton cells. Thus, our model provides a valuable tool for advancing the study of phytoplankton physiology, diversity, and evolution.
Presentation, Calibration and Testing of the DCESS II Earth System Model of Intermediate Complexity (version 1.0)
Esteban Fernández and Gary Shaffer
Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2024-122,2024
Preprint under review for GMD (discussion: open, 0 comments)
Here we describe, calibrate and test DCESS II, a new, broad, adaptable and fast Earth System Model. DCESS II has been designed for global simulations over time scales of years to millions of years using limited computer resources like a personal computer. With its flexibility and comprehensive treatment of the global carbon cycle, DCESS II should prove to be a useful, computational-friendly tool for simulations of past climates as well as for future Earth System projections.
The DOE E3SM Version 2.1: Overview and Assessment of the Impacts of Parameterized Ocean Submesoscales
Katherine Smith, Alice M. Barthel, LeAnn M. Conlon, Luke P. Van Roekel, Anthony Bartoletti, Jean-Christophe Golez, Chengzhu Zhang, Carolyn Branecky Begeman, James J. Benedict, Gautum Bisht, Yan Feng, Walter Hannah, Bryce E. Harrop, Nicole Jeffery, Wuyin Lin, Po-Lun Ma, Mathew E. Maltrud, Mark R. Petersen, Balwinder Singh, Qi Tang, Teklu Tesfa, Jonathan D. Wolfe, Shaocheng Xie, Xue Zheng, Karthik Balaguru, Oluwayemi Garuba, Peter Gleckler, Aixue Hu, Jiwoo Lee, Ben Moore-Maley, and Ana C. Ordonez
Geosci. Model Dev. Discuss., https//doi.org/10.5194/gmd-2024-149,2024
Preprint under review for GMD (discussion: open, 0 comments)
Version 2.1 of the U.S. Department of Energy's Energy Exascale Earth System Model (E3SM) adds the Fox-Kemper et al. (2011) mixed layer eddy parameterization, which restratifies the ocean surface layer through an overturning streamfunction. Results include surface layer biases reduction in temperature, salinity, and sea-ice extent in the North Atlantic, a small strengthening of the Atlantic Meridional Overturning Circulation, and improvements in many atmospheric climatological variables.
Mitigating Radome Induced Bias in X-Band Weather Radar Polarimetric moments using Adaptive DFT Algorithm
Thiruvengadam Padmanabhan, Guillaume Lesage, Ambinintsoa Volatiana Ramanamahefa, and Joël Van Baelen
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2024-117,2024
Preprint under review for AMT (discussion: open, 0 comments)
This study explores how the joints in a weather radar's protective cover affect its measurements. We developed a new method to correct these errors, improving the accuracy of the radar's data. Our method was tested during an intense cyclone on Reunion Island, demonstrating significant improvements in data accuracy. This research is crucial for enhancing weather predictions and understanding, particularly in challenging terrains.
Abstract
An approach for creating continental-scale, multi-scale plasma convection maps in the nightside high-latitude ionosphere using the spherical elementary current systems technique has been developed and evaluated. The capability to reconstruct meso-scale flow channels improved dramatically, and the velocity errors were reduced by ∼30% compared to the spherical harmonic fitting method. Uncertainties of velocity vectors estimated by varying the model setup was also low. Convection maps for a substorm event revealed multiple flow channels in the polar cap, dominating the convection in the quiet time and early growth phase. The meso-scale flows extended toward the nightside auroral oval and had continuous flow channels over >20° of latitude, and the flow channels dynamically merged and bifurcated. The substorm onset occurred along one of the flow channels, and the azimuthal extent of the enhanced flows coincided with the initial width of the auroral breakup. During the expansion phase, the meso-scale flows repetitively crossed the oval poleward boundary, and some of them contributed to subauroral polarization streams enhancements. Increased flows extended duskward, along with the westward traveling surge. Then, flows near midnight weakened and evolved to the Harang flow shear. The meso-scale flow channels had significant (∼10%–40% on average) contributions to the total plasma transport. The meso-scale flows were highly variable on ∼10 min time scales and their individual maximum contributions reached upto 73%. These results demonstrate the capability of specifying realistic convection patterns, quantifying the contribution of meso-scale transport, and evaluating the relationship between meso-scale flows and localized auroral forms.
Probabilistic short-range forecasts of high-precipitation events: optimal decision thresholds and predictability limits
François Bouttier and Hugo Marchal
Nat. Hazards Earth Syst. Sci., 24, 2793–2816, https://doi.org/10.5194/nhess-24-2793-2024, 2024
Weather prediction uncertainties can be described as sets of possible scenarios – a technique called ensemble prediction. Our machine learning technique translates them into more easily interpretable scenarios for various users, balancing the detection of high precipitation with false alarms. Key parameters are precipitation intensity and space and time scales of interest. We show that the approach can be used to facilitate warnings of extreme precipitation.
Water depth estimate and flood extent enhancement for satellite-based inundation maps
Andrea Betterle and Peter Salamon
Nat. Hazards Earth Syst. Sci., 24, 2817–2836, https://doi.org/10.5194/nhess-24-2817-2024, 2024
The study proposes a new framework, named FLEXTH, to estimate flood water depth and improve satellite-based flood monitoring using topographical data. FLEXTH is readily available as a computer code, offering a practical and scalable solution for estimating flood depth quickly and systematically over large areas. The methodology can reduce the impacts of floods and enhance emergency response efforts, particularly where resources are limited.
Modelling tsunami initial conditions due to rapid coseismic seafloor displacement: efficient numerical integration and a tool to build unit source databases
Alice Abbate, José M. González Vida, Manuel J. Castro Díaz, Fabrizio Romano, Hafize Başak Bayraktar, Andrey Babeyko, and Stefano Lorito
Nat. Hazards Earth Syst. Sci., 24, 2773–2791, https://doi.org/10.5194/nhess-24-2773-2024, 2024
Modelling tsunami generation due to a rapid submarine earthquake is a complex problem. Under a variety of realistic conditions in a subduction zone, we propose and test an efficient solution to this problem: a tool that can compute the generation of any potential tsunami in any ocean in the world. In the future, we will explore solutions that would also allow us to model tsunami generation by slower (time-dependent) seafloor displacement.
Dynamic Fragility of a Slender Rock Pillar in a Sedimentary Rock Mass – from rock mechanics to seismic hazard
Alaa Jbara and Michael Tsesarsky
Nat. Hazards Earth Syst. Sci. Discuss., https//doi.org/10.5194/nhess-2024-150,2024
Preprint under review for NHESS (discussion: open, 0 comments)
Fragile geological features are the only empirical data to validate seismic hazard analysis over prehistoric timescales. We present a fragility analysis of a 42 m high rock pillar. Based on LiDAR scanning and in-situ rock elastic modulus measurements, we developed an accurate finite element model. The model was validated by comparing computational modal analysis with in-situ measurements of natural vibrations. Dynamic fragility analysis was used to challenge regional seismic hazard estimates.
The ability of a stochastic regional weather generator to reproduce heavy precipitation events across scales
Xiaoxiang Guan, Dung Viet Nguyen, Paul Voit, Bruno Merz, Maik Heistermann, and Sergiy Vorogushyn
Nat. Hazards Earth Syst. Sci. Discuss., https//doi.org/10.5194/nhess-2024-143,2024
Preprint under review for NHESS (discussion: open, 0 comments)
We evaluated a multi-site stochastic regional weather generator (nsRWG) for its ability to capture the cross-scale extremity of high precipitation events (HPEs) in Germany. We generated 100 realizations of 72 years of daily synthetic precipitation data. The performance was assessed using WEI and xWEI indices, which measure event extremity across spatio-temporal scales. Results show nsRWG simulates well the extremity patterns of HPEs, though it overestimates short-duration, small-extent events.
Abstract
Severe storms produce ocean waves with periods of 18–26 s, corresponding to wavelengths 500–1,055 m. These waves radiate globally as swell, generating microseisms and affecting coastal areas. Despite their significance, long waves often elude detection by existing remote sensing systems when their height is below 0.2 m. The new Surface Water Ocean Topography (SWOT) satellite offers a breakthrough by resolving these waves in global sea level measurements. Here we show that SWOT can detect 25-s waves with heights as low as 3 cm, and resolves period and direction better than in situ buoys. SWOT provides detailed maps of wave height, wavelength, and direction across ocean basins. These measurements unveil intricate spatial patterns, shedding light on wave generation in storms, currents that influence propagation, and refraction, diffraction and reflection in shallow regions. Notably, the magnitude of reflections exceeds previous expectations, illustrating SWOT's transformative impact.
Abstract
Megathrusts at convergent plate boundaries generate the largest and some of the most hazardous earthquakes on Earth. However, their physical properties, including those influencing fault slip accumulation and release and earthquake-related surface displacements, are still poorly constrained at critical depths. Here, we combine seismic imaging and geodetic modeling to investigate the structure and mechanical behavior of the Main Himalayan Thrust fault (MHT) in the center of the 2015 Mw 7.8 Gorkha rupture in Nepal. Our results from two independent observations consistently suggest the presence of a channel associated with the MHT with high compliance (shear modulus as low as ∼4 GPa) and strain anisotropy (stiffer in the vertical orientation than in the horizontal), likely arising from a weak subducting layer with north-dipping foliation. Such mechanical heterogeneity significantly influences the quantification of short-term fault kinematics and associated earthquake potential, with implications on across-scale dynamics of plate boundaries in Himalaya and elsewhere.
