In this paper we will propose a possible solution for the density parameter of dark energy. From the dimensionless unification of the fundamental interactions will be presended the formulas for the density parameter of dark energy. Also we will show the geometric representation of the density parameter for dark energy and the geometric representation of the relationship between the de Sitter radius and the Hubble length.

A document by Kyle Duncan. Click on the document to view its contents.

Atmospheric methane directly affects surface temperatures and indirectly affects ozone, impacting human welfare, the economy, and environment. The social cost of methane (SC-CH­4) metric estimates the costs associated with an additional marginal metric ton of emissions. Current SC-CH­4 estimates do not consider the indirect impacts associated with ozone production from changes in methane. We use global model simulations and a new BenMAP webtool to estimate respiratory-related deaths associated with increases in ozone from a pulse of methane emissions in 2020. By using an approach consistent with the current SC-CH­4 framework, we monetize and discount annual damages back to present day values. We estimate that the methane-ozone mechanism is attributable to 760 (95% CI: 330-1200) respiratory-related deaths per million metric tons (MMT) of methane globally, for a global net present damage of $1800/mT (95% CI: $760-$2800/mT CH­4; 2% Ramsey discount rate); this would double the current SC-CH­4 if included. These physical impacts are consistent with recent studies, but comparing direct costs is challenging. Economic damages are sensitive to uncertainties in the exposure and health risks associated with tropospheric ozone, assumptions about future projections of NOx emissions, socioeconomic conditions, and mortality rates, monetization parameters, and other factors. Our estimates are highly sensitive to uncertainties in ozone health risks. We also develop a reduced form model to test sensitivities to other parameters. The reduced form tool runs with a user-supplied emissions pulse, as well as socioeconomic and precursor projections, enabling future integration of the methane-ozone mechanism into the SC-CH­4 modeling framework.

This work advances the incorporation and cross-model deployment of multi-biogeochemistry and ecological simulations in existing process-based hydro-modelling tools. It aims to transform the current practice of water quality modelling as an isolated research effort into a more integrated and collaborative activity between science communities. Our approach, which we call “Open Water Quality” (OpenWQ), enables existing hydrological, hydrodynamic, and groundwater models to extend their capabilities to water quality simulations, which can be set up to examine a variety of water-related pollution problems. OpenWQ’s objective is to provide a flexible biogeochemical model representation that can be used to test different modelling hypotheses in a multi-disciplinary co-creative process. In this paper, we introduce the general approach used in OpenWQ. We detail aspects of its architecture that enable its coupling with existing models. This integration enables water quality models to benefit from advances made by hydrologic- and hydrodynamic-focused groups, strengthening collaboration between the hydrological, biogeochemistry, and soil science communities. We also detail innovative aspects of OpenWQ’s modules that enable biogeochemistry lab-like capabilities, where modellers can define the pollution problem(s) of interest, the appropriate complexity of the biogeochemistry routines, and test different modelling hypotheses. In a companion paper, we demonstrate how OpenWQ has been coupled to two hydrological models, the “Structure for Unifying Multiple Modelling Alternatives” (SUMMA) and the “Cold Regions Hydrological Model” (CRHM), demonstrating the innovative aspects of OpenWQ, the flexibility of its couplers and internal spatiotemporal data structures, and the versatile eco-modelling lab capabilities that can be used to study different pollution problems.

Salmon spawning activities alter streambed morphology, forming a dune-shaped egg nest called a redd. The spawning process increases redd sediment hydraulic conductivity, KD, and congregates large sediment grains to form an egg pocket, such that egg pocket hydraulic conductivity, KEP, may be higher than KD. Salmon females may create one or more egg pockets within a single redd. Although the impact of redd shape and KD on redd-induced hyporheic fluxes has been studied, the effects of streambed roughness, R, egg pocket permeability, and egg pocket location on egg pocket hyporheic fluxes have not yet been quantified. This study investigates this knowledge gap with a set of numerical simulations supported by flume experiments. We simulated hyporheic flows for five egg pocket locations, five KEP values from 0.0025 to 0.02 m/s, and 12 rough streambed surfaces. Surface roughness was scaled from a measured streambed surface in two ways - only vertically (R1) and both vertically and horizontally (R2) - with scaling coefficients ranging from 0.5 to 3. The measured streambed surface had a median diameter, D50, of 1 cm and a standard deviation of 0.77 cm. The results indicated that the dimensionless flux into the egg pocket increases noticeably with the downstream distance of egg pockets from the redd pit, and less strongly with KEP*=KEP/KD. The near-surface downwelling fluxes significantly increase with R1, but only negligibly with R2, and for deeper egg pockets, flux into the egg pocket is minimally impacted by surface roughness.

The hydraulic properties of hydric soils in Tibet’s peatlands significantly influence hydrological processes and play a substantial role in carbon cycle. Soil hydraulic studies on the peatlands remain strikingly limited. By the comparison of six hydraulic parameterizations using either van Genuchten-Mualem (vGM) or Kosugi saturation function, the results indicate that the PDI (Peter-Durner-Iden) model remains an excellent choice for these multi-disperse systems composed of mixed components, despite substantial discrepancies in the micrometer-scale morphology of structure and composition of partially decomposed Sphagnum and vascular tissues and mineral particles. The bi-modal scheme does not adapt well in the later stages of the Evaporation Experiment (EE), as of the bi-modal scheme deviates in the dry range of the water retention curve (WRC). Nonetheless, Irrespective of the saturation functions, the bi-modal with PDI yields satisfactory results for the WRC and the hydraulic conductivity curve (HCC). We attribute this to the complementary effects of two uni-modals. But for bi-modal PDI scheme, vGM demonstrates better performance than the Kosugi in high clay content samples. These clay-rich samples exhibit a broader and more heterogeneous feature in the equivalent Pore Size Distribution (PSD), while other samples generally show a broad and relatively homogeneous feature. Therefore, we conclude that the WRC and HCC are jointly determined by structures and compositions of mixed components of lignocellulosic, humin and mineral materials. Intricate nature of these components underscore the necessity for extensive comprehensive field sampling and laboratory analyses to accurately capture the hydraulic characteristics in the peatlands of Tibet.

Seasonal-to-decadal climate prediction is crucial for decision-making in a number of industries, but forecasts on these timescales have limited skill. Here, we develop a data-driven method for selecting optimal analogs for seasonal-to-decadal analog forecasting. Using an interpretable neural network, we learn a spatially-weighted mask that quantifies how important each grid point is for determining whether two climate states will evolve similarly. We show that analogs selected using this weighted mask provide more skillful forecasts than analogs that are selected using traditional spatially-uniform methods. This method is tested on two prediction problems within a perfect model framework using the Max Planck Institute for Meteorology Grand Ensemble: multi-year prediction of North Atlantic sea surface temperatures, and seasonal prediction of El Niño Southern Oscillation. This work demonstrates a methodical approach to selecting analogs that may be useful for improving seasonal-to-decadal forecasts and understanding their sources of skill.

Flash flooding is one of the most damaging weather types, yet it remains challenging to quantify its severity. We propose a novel development – the Flashiness-Intensity-Duration-Frequency (F-IDF) curve – to quantify and spatially analyze flash flood intensity based on the frequency and duration of the event. As a proof-of-concept, we mapped Contiguous US (CONUS)-wide F-IDF values at 3,722 stream gage locations and explored their relations with 59 basin attributes. It is found that (1) Climatological precipitation amounts exhibit the most positive correlation with flashiness while a basin’s drainage area is the most negatively correlated; (2) Correlation of flashiness with basin attributes decreases with increasing F-IDF return periods and shorter event durations. Both aspects are attributable to the rainfall signal overwhelming the underlying basin attributes as the intensities become more extreme. This new term can have implications for hydrology, especially for hydrologic modelers, decision-makers, and emergency responders.

We investigate electrostatic waves in a magnetopause reconnection diffusion region event. In the electron diffusion region on the magnetospheric side, an oblique electrostatic wave is observed. The local distribution exhibits fast non-gyrotropic electron beams with drifts comparable to the electron thermal speed, but the wave has a much lower phase speed. Response of ions and possible cold electrons may contribute to wave excitation. Near the current sheet mid-plane, parallel electron beam-mode waves are modulated by whistler waves. In the separatrix region, parallel waves associated with field-aligned electron beams and perpendicular electron cyclotron waves with loss cone distributions exhibit modulation frequencies in the lower-hybrid wave frequency range. We infer that lower-hybrid waves scatter electrons to produce beams and alter loss cones to modulate electrostatic waves. The results advance our understanding about the regimes and mechanisms of electrostatic waves in reconnection and their coupling with lower-frequency waves.

Teleseismic shear-wave splitting analyses are typically performed by reversing the splitting process through the application of frequency- or time-domain operations minimizing transverse-component waveforms. These operations yield two splitting parameters, φ (fast-axis orientation) and δt (delay time). In this study, we investigate the applicability of a recurrent neural network, SWSNet, for determining the splitting parameters from pre-selected waveform windows. Due to the scarcity of sufficiently labelled real waveform data, we generate our own synthetic training dataset. The model is capable of determining φ and δt with a root mean squared error (RMSE) of 9.58◦ and 0.143 s for noisy synthetic test data. The application to real data involves a deconvolution step to homogenize the waveforms. When applied to data from the USArray dataset, the results exhibit similar patterns to those found in previous studies with mean absolute differences of 11.12◦ and 0.25 s in the calculation of φ and δt, respectively.

A physically based analytical model is formulated to simulate the thaw depth of active layer under changing boundary condition of soil heat flux. The energy conservation statement leads to a nonlinear integral equation of the thaw depth using an approximate temperature profile as an analytical solution of the diffusion equation describing the heat transfer in the active layer. The time-varying soil surface heat flux is estimated using non-gradient models when field observations are not available. The proposed model was validated against field observations at three Arctic forest and tundra sites. The simulated thaw depth and soil temperature profiles are in good agreement with observations hinting the potential for model application at larger spatial scales.

Africa’s continental crust hosts a variety of geologic terrains and is crucial for understanding the evolution of its longest-lived cratons. However, few of its seismic models are yet to incorporate the largest continent-wide noise dispersion datasets collected on the continent. Here, we report on new insights into Africa’s crustal architecture obtained using a new dataset and model assessment product, ADAMA, which comprises a large ensemble of short period surface wave dispersion measurements. We construct a continent-wide model of Africa’s Crust Evaluated with ADAMA’s Rayleigh Phase maps (ACE-ADAMA-RP). Phase and group dispersion maps are obtained with a probabilistic inverse modeling approach allowing us to provide constraints on uncertainty.  Error statistics suggest Rayleigh phase maps are better resolved and a perturbational inverse approach based on Rayleigh waves is the basis of our update of Africa’s crustal shear velocity. This model update reveals new insights into the architecture of Africa’s crust not previously imaged: (1) the fastest velocities confined to the edges of the Congo craton, the west-African cratons and the Sahara Metacraton, and (2) sharp spatial gradients along craton edges, mobile belts, and within rifted margins. While most of the reported features are robust, probabilistic modeling suggests caution in interpreting features where illumination is compromised by low-quality measurements, sparse coverage or both. Future extension of our approach to other complementary seismic and geophysical datasets - e.g, multimode earthquake dispersion, receiver functions, gravity and mineral physics, will enable continent-wide lithospheric modeling that extends resolution to the upper mantle.

In October 2020, Congress passed the Promoting Research and Observations of Space Weather to Improve the Forecasting of Tomorrow (PROSWIFT) Act. The Space Weather Advisory Group (SWAG) was chartered, pursuant to PROSWIFT, to advise the Space Weather Operations, Research and Mitigation Subcommittee (SWORM) on a variety of space weather issues including the development and implementation of an integrated strategy for space weather (i.e., the National Space Weather Strategy and Action Plan).  The SWAG is comprised of 15 non-government members  from academia, the commercial space weather sector, and end users. In June 2022, the SWAG was tasked to provide input to the SWORM for their update of the National Space Weather Strategy and Action Plan.  To accomplish this, SWAG sought broad input from the national space weather enterprise through multiple open meetings and structured panel sessions with community stakeholders.The SWAG report, Findings and Recommendations to Successfully Implement PROSWIFT and Transform the National Space Weather Enterprise(SWAG, 2023), notes that since the publication of the first National Space Weather Strategy in 2015, the national space weather enterprise has made noteworthy progress in several areas. These include raising awareness of space weather and its effects, improving understanding and forecasting of space weather, and enhancing the Nation’s preparedness for space weather events. However, substantial investments are still needed to build resilience and ensure space weather services can continue to improve and meet the growing and changing needs of the Nation.To address these issues, SWAG identified 25 findings with 56 recommendations. Eleven of the recommendations were designated as highest-priority by the SWAG. They call for coordination across the entire space weather enterprise (including government, academic, and commercial sectors).  One of the highest priority recommendations is the urgent need to adequately fund the space weather enterprise.  The report recognized that the “Federal space weather enterprise is insufficiently funded to implement PROSWIFT actions, perform the codified roles and responsibilities, or appropriately address the risk space weather poses to the Nation”.Other high-priority recommendations point to improvements and changes needed in thee National Oceanic and Atmospheric Administration (NOAA) and National Aeronautics and Space Administration (NASA), to accomplish the following operational and scientific goals:“Create and fund an applied research program office for space weather within NOAA to coordinate, facilitate, promote, and transition applied research across the national space weather enterprise”,“Provide long-term support for operational ground-based and airborne sensors and networks”,“Provide and fund critical operational space weather services beyond near-Earth”, including “meeting near-Earth operational needs and expanding support and funding for space weather services in medium-Earth orbit, geostationary Earth orbit, geostationary transfer orbit, cis-Lunar, and eventually Martian environments”,“Fund NASA missions that advance fundamental science to support space weather research“, and“Support coordinated applied research within the thermosphere (above 100 km altitude) which is critical for space traffic coordination”.The goals outlined in the report are ambitious. They call for the funding, processes, and structure needed to foster transformative change across the national space weather enterprise . The PROSWIFT Act authorizes many of the actions needed to improve national response to threats from space weather. It must now be followed with sufficient new appropriations to ensure that space weather is supported at a level commensurate with the increasing risks that it poses to the Nation and society.SWAG looks forward to opportunities to engage the community on these findings and recommendations and evaluate the implementation and evolution of the national space weather enterprise, across all segments–Federal, academic, and commercial.*The members of the SWAG are Dr. Tamara Dickinson, Mr. Mark Olson, Mr. Michael Stills, Mr. Craig Fugate, Dr. Rebecca Bishop, Dr. Jennifer Gannon, Dr. Conrad Lautenbacher, Dr. Seth Jonas, Dr. Kent Tobiska, Dr. Nicole Duncan, Dr. Tamas Gombosi, Dr. Delores Knipp, Dr. Scott McIntosh, Dr. Heather Elliott, Dr. George Ho, Dr. Jinni Meehan (for more information and member bios, see www.weather.gov/swag).ReferencesS.881 - 116th Congress (2019-2020): PROSWIFT Act, Library of Congress, 21 October 2020, http://www.congress.gov/, accessed June 18, 2022.SWAG (2023), Findings and Recommendations to Successfully Implement PROSWIFT and Transform the National Space Weather Enterprise, https://www.weather.gov/swag, accessed June 13, 2023.

A document by Laura Vuorinen. Click on the document to view its contents.

In recent years, seismic-noise based methods have shown great potential for the monitoring of various processes occurring in the Earth's crust. Among them, the fine detection of hydrological variations at different scales is a major issue in the context of water resources management (Gaubert-Bastide et al. 2022). In order to better understand the sensitivity of continuous seismic wavefields to water content variations affecting both saturated and unsaturated zones, we have set up a dynamic and meter-scale laboratory experiment. This sandbox experiment reproduces field surveys based on the recording and processing of seismic background noise (hundred to kiloHertz range) in the context of hydrological variations. These multiple measurements, which benefit from independent measurements of pressure and water saturation at different depths, allow us to refine the sensitivity of the seismic wavefield to variations in water content and hysteretic behavior related to different phases of imbibition/drainage.

Momentum exchange between ocean tidal waves of different frequencies facilitates energy transfer and dissipation. However, such mechanisms are poorly understood, and how such processes will change in a warmer ocean is unclear. Inviscid triads are nonlinear interactions involving three waves whose frequencies sum to zero; at least one of the waves is always internal. Triads exchange energy on a time scale slower than the frequencies of the original waves and can occur in resonant and non-resonant forms. Triad interactions are possible in a variety of media (e.g., light waves), and also occur in the ocean, especially for ocean tides. Here, we detail triad interactions between the M2, K1, and O1 tides in three complex regions of the Western Pacific Ocean: The South China Sea, The Solomon/Bismarck Sea region, and the Coral Sea along the eastern coast of Australia. We develop simplified diagnostic versions of the triad interaction equations and examine the amplitude, phase-lock, energy balance, and wavenumber match of each triad. Strongly resonant triads are prevalent in the Gulf of Thailand/Malacca Strait, in the Solomon Sea/Bismarck Sea, and along the eastern coast of Australia, with isolated triads seen in the South China Sea. All triads are found near regions of complex bathymetry and intense internal tide generation and activity, which provide the most likely explanation for their occurrence. However, triad properties are strongly dependent on latitude, local stratification, and depth; the latter two will change as the ocean warms and sea level rises.

Methane dynamics within salt marshes are complex because vegetation types, temperature, oscillating water levels, and changes in salinity and redox conditions influence CH4 production and emission. These non-linear and complex interactions among variables affect the traditionally expected functional relationships and present challenges for interpretation and developing process-based models. We employ empirical dynamic modeling (EDM) and convergent cross mapping (CCM) as a novel approach for characterizing seasonal/multiday and diurnal CH4 dynamics by identifying causal variables, lags, and interconnections among multiple biophysical variables within a temperate salt marsh using five years of eddy covariance data. EDM/CCM is a nonparametric approach capable of quantifying the coupling between variables while determining time scales where variable interactions are most relevant. We found that gross primary productivity, tidal creek dissolved oxygen, and temperature were important for seasonal/multiday dynamics (rho=0.73-0.80), while water level was most important for diurnal dynamics during both the growing and dormancy phenoperiods (rho=0.72 and 0.56, respectively). Lags for top causal variables (gross primary productivity, tidal creek dissolved oxygen, temperature, water level) occurred between 1-5 weeks at the seasonal scale and 1-24 hours at the diurnal scale. The EDM had high prediction capabilities for intra-/inter-seasonal patterns and annual CH4 sums but with limitations to represent large infrequent fluxes. Results highlight the importance of non-linearity, causal drivers, lag times, and interconnections among multiple biophysical variables that regulate CH4 fluxes in tidal wetlands. This study presents a new dimension for analyzing CH4 fluxes, which will prove helpful to test current paradigms in wetlands and other ecosystems.

Submarine groundwater discharge (SGD) is a globally important process supplying nutrients and trace elements to the coastal environment, thus playing a pivotal role in sustaining marine primary productivity. Along with nutrients, groundwater also contains allochthonous microbes that are discharged from the terrestrial subsurface into the sea. Currently, little is known about the interactions between groundwater-borne and coastal seawater microbial populations, and their role upon introduction to coastal seawater populations. Here, we investigated seawater microbial abundance, activity and diversity in a site strongly influenced by SGD (in-situ observations), and through laboratory-controlled bottle incubations mimicking different mixing scenarios between SGD (either ambient or filtered through 0.1 µm/0.22 µm) and seawater. Our results demonstrate that the addition of <0.1 µm SGD stimulated heterotrophic activity and increased microbial abundance compared to control, whereas <0.22 µm filtration treatments induced primary productivity rates and Synechococcus growth. Amplicon sequencing of the 16S rRNA gene showed a strong shift from a SAR11-rich community in the reference SGD-unaffected coastal samples to a Rhodobacteraceae-dominated one in the <0.1 µm treatment, in agreement with their in-situ enrichment in the SGD field site. These results suggest that despite the significant nutrient input, microbes delivered by SGD may affect the abundance, activity and diversity of intrinsic microbes in coastal seawater. Our results highlight the cryptic interplay between groundwater and seawater microbes in coastal environments, which has important implications for carbon cycling.