An advanced hodograph technique was applied to extract quasi-monochromatic, linear gravity wave (GW) packets from simultaneous wind and temperature measurements by a ground-based Doppler-Rayleigh-Mie-Raman lidar located in Kühlungsborn (54\,\textdegree N, 12\,\textdegree E). During the night of 11 to 12 February 2022, the stratospheric polar vortex was slightly elongated towards Central Europe. The polar night jet’s (PNJ) core was located nearly above the lidar. This unique meteorological situation allowed horizontal wind and temperature measurements in a stratospheric high-wind speed regime. GW refraction in the strong vertical gradient of the horizontal winds associated with the PNJ was observed. In addition, the subsequent low-pass filtering of upward and downward propagating GWs in the strong winds of the PNJ was demonstrated. A pair of upward and downward propagating GWs at the top and bottom edge of the PNJ’s core could be the result of shear excitation in the PNJ. A statistical analysis of intrinsic GW parameters is provided for all resolved linear GWs. Approximately 35\,\% of the resolved GWs propagate downward, and there is stronger filtering of the downward waves compared to the upward waves by the PNJ core. ECMWF-IFS horizontal winds and temperatures had a lower variability than the lidar and a poorer overall agreement above 50\,km. Stratospheric temperatures in ECMWF show a cool bias of greater than 2\,K.

The concept of optimality in geostatistical inversion is traditionally rooted in a Euclidean framework, which often oversimplifies complex spatial relationships in geological structures, potentially leading to suboptimal representations of subsurface properties. This study challenges this conventional approach by introducing manifold embedding, a method that incorporates non-Euclidean geometries to better capture the complex and non-stationary nature of geological structures. Through the application of Kalman filtering (KF) and geostatistical principal component adaptation evolution strategy (GPCA-ES), we explore how different geometric frameworks influence the outcomes of hydraulic conductivity estimations in a synthetic aquifer. Our results demonstrate that while Euclidean-based methods may provide a single “optimal” solution, they do not necessarily yield the most geologically accurate models. By incorporating manifold geometries, we reveal a broader range of plausible subsurface interpretations, all of which produce similar hydraulic responses at observation points. This finding highlights the limitations of relying solely on Euclidean assumptions and challenges the conventional notion of a unique optimal solution in hydrogeological inverse problems. The study underscores the importance of adopting a more comprehensive geometric perspective in hydrogeological modeling, offering a pathway to more geologically meaningful and potentially more reliable subsurface characterizations. These findings advocate for a fundamental shift in the approach to geostatistical inversion, emphasizing the need to move beyond traditional optimality criteria and toward a more nuanced understanding of subsurface environments that acknowledges the inherent complexity and non-uniqueness of geological structures.

We perform azimuth time tracking of multiple thunderstorm centers on the globe, which are sources of extremely low frequency (ELF) electromagnetic waves propagating in the spherical Earth-ionosphere cavity. For observations made in September 2023 we identify azimuths of numerous global emission centers using our data sampled at 3 kHz at the Hylaty station in Poland. We confirm significant and relatively regular thunderstorm azimuth variation during the solar terminator passage over the observation site. The magnitude and duration of the azimuth deviations depend on the observed azimuths but are also varying between successive days and changing detailed thunderstorm activity patterns. The measured maximum positive (preferentially at the sunrise time) and negative (preferentially at the sunset time) azimuth deviations reach even above 20 for waves propagating close to the terminator. We discovered also particular composite deviation structures, with the negative azimuth deviation directly preceding a larger positive one, as occurring during the morning terminator passage. At azimuths distant from the terminator one can observe decreasing of the regular deviation magnitude and occasionally lower magnitude deviations with opposite sign. Variations of the observed azimuth time structures between successive days are expected to result from varying thunderstorm activity on Earth as well variability of ionospheric parameters, in particular of charge gradients and nonuniformities occurring along the terminator. We postulate that the observed deviations result from a signal diffraction at the varying ionospheric gradients.

A document by Liam Cassidy. Click on the document to view its contents.

The impact of climate change on the intensity of mid-latitude cold air outbreaks is a debated topic due to uncertainty associated with internal atmospheric dynamics. Here, we employ an event-based storyline approach in which the evolution of the large-scale atmospheric circulation is nudged to reanalysis data at different global warming levels based on historical and high-emission scenario simulations. We thereby quantify the thermodynamic climate-change effects of pre-industrial, 2ºC and 4ºC warmer climates compared to present-day climate for three cold surges in East Asia during the winter 2020/21. The strongest warming occurs over northeast Asia, reaching up to +12ºC in a +4ºC warmer climate and caused by the advection of less cold air from winter ice-free regions in the Arctic, where the change of surface air temperature exceeds +20ºC. In contrast, over southern China, a moderate cooling is present from pre-industrial to present-day climates, due to the observed and expected increase in aerosol concentration, which peaks by the mid-21st century and alters the radiative balances. This cooling effect is likely to persist well into a +2ºC-warmer climate; however, it may become undetectable at the end of the 21st century (+4ºC warming). In summary, our findings underscore the important thermodynamic impact associated with Arctic amplification and cooling effect of aerosol-induced changes in the radiation budget on East Asian cold extremes.

A connection between the quasi-biennial oscillation (QBO), the 11-yr solar cycle (SC), and the short-term convective climate oscillation, the Madden-Julian Oscillation (MJO), in boreal winter has been found in observational data, yet is generally lacking in current global climate models (GCMs). The extent to which a proposed mechanism for producing this connection is simulated in a series of GCMs participating in the Coupled Model Intercomparison Project 6 (CMIP6) is investigated. The models are found to be often lacking complete representation of several elements of this mechanism, with particular issues being QBOs that are westerly-biased and weak in the lower stratosphere, weak solar stratospheric temperature and zonal wind signals, insufficient solar or QBO-modulation of extratropical wave activity (the Holton-Tan effect), too weak reductions in equatorial tropopause static stability in response to extratropical wave forcing, and MJOs that in some cases do not respond to these reductions. Through by-passing many of these deficiencies via data selection, it is demonstrated that effects on the MJO that resemble those found in observations (strengthening of the MJO following early-winter sudden stratospheric warmings and during easterly QBO winters) can be simulated by a subset of the models. This supports operation of the proposed mechanism, and points to needed model improvements, although additional feedbacks may be needed to reproduce the full modulation.

Sulfur-containing species are suggested as the UV-absorbers in Venus’s atmosphere, which can be generated by photochemistry or electrochemistry. Here we report an electrical discharge experiment in gas mixtures of SO2 with CO2 and N2, under the pressure and temperature conditions relevant to the Venus cloud layer. We directly observed the primary breakdown products of SO2 as free radicals SO*, SI*, SII*, S2*, OI*, OII*; and the stable ending products as S8 particles and H2SO4 droplets. Their generations in minutes imply the formation of short-lived intermediate phases, including polysulfur and sulfur-oxides, as recognized candidates for the mysterious UV-absorber. The simultaneous occurrence of SO*and S2* under all experimental conditions indicates an equal probability for two major breakdown processes and their products. Compared with photochemistry, the high yields of reactive S-species from local electrochemistry would be responsible for the inhomogeneous distribution and temporal changes of dark strips in Venus UV images.

Evaluating the combined effect of different climatic variables supports the understanding of the increasing multifaceted risk of climate-related disasters. This contribution proposes a combined trend analysis of precipitation-related (precipitation total, PRCPTOT; maximum one-day precipitation, RX1day) and temperature-related (minimum of daily minimum temperature, TNn; mean of daily mean temperature, Tmean; maximum of daily maximum temperature, TXx) indices at the annual scale from 1955 to 2023, both at local (Southern Italy, using ground-based observations) and continental (pan-European EURO-Cordex domain, using ERA5-Land data) scales. While showing substantial consistency between the different datasets, the results imply that at the continental scale, three main regions along a latitudinal gradient can be considered regarding increasing/decreasing trends towards both PRCPTOT and RX1day. At the same time, much more homogeneous increasing trends of temperature indices are observed in Europe. Nevertheless, the detailed scale analysis highlights the need for higher resolutions to capture significantly impacting local counter-trends.

Ocean water turbidity, influenced by marine chlorophyll concentration, significantly alters the distribution of shortwave radiation in the water column. This work aims to assess the effects of turbidity on the upper-ocean physical properties and their subsequent impact on the atmosphere, using a coupled ocean-atmosphere regional model for the Mediterranean and Black Seas. We performed 11-year (2011-2021) twin-simulation experiments, based on different chlorophyll concentrations to estimate turbidity and the penetration of solar radiation in the ocean. The first simulation used a monthly climatology field of chlorophyll concentrations derived from satellite observations, whilst in the second experiment, the chlorophyll concentration was kept constant at 0.05 mg m−3, representing clear water turbidity conditions. Results show that radiative heating driven by ocean turbidity amplifies the seasonal cycle of temperature in the upper layers, leading to increased surface warming in summer and surface cooling in winter. Also, higher turbidity contributes to cooling in subsurface layers throughout the year due to its shading effect. The temperature response to turbidity in the water column is controlled by the mixed layer depth and a balance between (1) direct near-surface radiative heating due to chlorophyll solar absorption, and (2) indirect cooling resulting from vertical turbulent mixing processes with subsurface waters. The atmosphere moderates the seasonal sea surface temperature (SST) response to turbidity, primarily through changes in latent heat flux. Ultimately, our simulations suggest that increased turbidity enhances the Mediterranean overturning circulation, highlighting the necessity of incorporating realistic turbidity forcing into regional climate modeling studies.

Ocean general circulation models (OGCMs) contain numerous parameterizations of sub-grid scale processes. The parameter tuning procedure is rarely reported and often done by hand. We present an automated alternative: Bayesian optimization, a method which has recently emerged as a frontier in expensive black box optimization. VerOpt, a Python package for the ocean model Veros, adapts Bayesian optimization to climate model tuning. We use VerOpt to identify a set of parameter values of the Turbulent Kinetic Energy (TKE) closure scheme that minimize mixed layer depth (MLD) bias in Veros. We present the results of two optimization procedures: TWIN and OBS. The goal is to minimize modeled MLD error relative to a target map. In TWIN, the target is MLD simulated using Veros with a known parameterization. The ratio of two TKE parameters ckcϵ-1, proportional to the critical Richardson number Ric, is the dominant factor in setting the global MLD. After 180 model simulations, the lowest error in the TWIN experiment is 1.18%. In OBS, the target is MLD climatology. The MLD bias is smallest when Ric<1, and the default TKE parameterization falls within this range. We find, however, that altering the TKE parameterization is not sufficient to reduce the significant MLD bias of 42.62%. The OBS experiment results indicate that the TKE scheme parameters are not the dominant source of MLD bias in Veros. We discuss other possible sources of MLD bias, as well as the potential of extending of the optimization procedure to other parameterizations.

Manuscript title – Word template for Applied Computing & Geosciences

A document by Galen Egan. Click on the document to view its contents.

Pressures on water resources are fueling conflicts between sectors. This trend will likely worsen under future climate-induced water stress, jeopardizing food, energy and human water security in most arid and semi-arid regions. Probabilistic analysis using stochastic optimization modeling can characterize multi-sector vulnerabilities and risks associated with future water stress. This study identifies the probabilistic trade-offs between agricultural, urban and energy sectors in the Ebro Basin (Spain). Two intervention policies have been examined and compared: (i) agricultural priority, and (ii) energy priority, for two planning horizons 2040-2070 and 2070-2100. Results show that the human water security goal is achieved under both intervention policies. However, the achievement of the food and energy security goals depends on the policy objectives and on the spatial location of irrigation schemes and hydropower plants, which result in different stream flows across the basin. The policy choice results in substantially different benefit gains and losses by sector and therefore by location. None of the sectoral production priority policy provides an equitable sharing of benefits among all sectors and locations under climate change, which is an important issue, because the success or failure of policy interventions would depend on the distribution of the gains and losses of benefits across the basin. Policy uptake by stakeholders would depend on reaching win-win outcomes where losers are compensated, while delivering acceptable levels of food, energy and human water security in large river basins. Information on the probabilistic trade-offs contributes to design water management strategies capable of addressing the multi-sector vulnerability.

Observations of March 2024 Arctic total column ozone set a record high of 478 Dobson Units (DU) against the 1979-2023 satellite era time series. It was about 60 DU higher than average and 6 DU higher than the previous March 1979 471 DU record. Daily Arctic ozone was above average for every day in March 2024, and set record highs from 11 to 26 March 2024. Microwave Limb Sounder data show this record ozone anomaly was concentrated in the lower stratosphere (10-30 km). These record values developed over the 2023-2024 winter and can be associated with vertically propagating planetary-scale wave events that caused significant stratospheric warmings. These wave events forced poleward and downward ozone advection into the lower stratosphere, leading to record column ozone levels. The above average levels persisted through June 2024 and will likely continue over the entire 2024 summer across the northern hemisphere.

Understanding equilibrium climate sensitivity (ECS, warming in response to a doubling of CO2) uncertainty is fundamental for making reliable climate projections. We leverage the Hector simple climate model in a probabilistic framework to explore how different ECS priors influence long-term (2081-2100) temperature anomalies. Specifically, we quantify how different ECS prior distributions broaden the uncertainty in temperature projections. This method demonstrates a computationally efficient probabilistic workflow that explores the effects of parameter priors on climate projections. Excluding process and paleoclimate evidence widens the resulting temperature projection uncertainty (1.12-3.03 ℃ and 1.09-3.33 ℃, respectively) while using priors that synthesize all lines of evidence leads to narrowed temperature projection uncertainty (1.24-2.89 ℃). Our study shows that excluding paleoclimate and process data in ECS priors broadens temperature projection uncertainty. In contrast, synthesized evidence provides a narrower and potentially more robust range of future temperature outcomes.

 Net and anthropogenic CO 2 exchange in the Pacific represents a major contribution to the global CO 2 sink.  The Pacific is thought to have turned to a net sink of CO 2 that is growing primarily due to the increasing uptake of anthropogenic CO 2.  The equatorial region is key in determining net and anthropogenic CO 2 uptakes and their trends and variability in the Pacific.

The process of two-phase fluid displacement in the porous medium is still poorly understood partly due to the absence of effective reconstruction methods featured in a 3D real-time fashion. This manuscript proposes the application of thermoacoustics (TA) imaging, an emerging real-time imaging technique, to reconstruct the dynamic surfactant-enhanced imbibition process into the oil-saturated sand. It is both theoretically and experimentally demonstrated that a significant TA contrast exists between the water-saturated sand and oil-saturated sand under the same microwave power. In the experiment, a U-shaped infiltration path is embedded 20mm underneath the oil-saturated sand as the ground truth profile of the water flow. A calibration process is conducted to account for the amplitude attenuation and velocity dispersion effects of the TA wave in the sand, and a two-layered medium sensing matrix is built for the inversion process. The reconstructed images match well with the infiltration path, which makes it feasible to monitor the subsurface 3D water-oil displacement in non-transparent porous sand in a real-time fashion.

Besides the forces described by Newtonian dynamics, there is an additional cosmological force in the Universe, which is observed in experiments, but does not follow from Newton's law of gravitation. The additional cosmological force was not represented in Newtonian dynamics. The law of cosmological force Fcos = (mc^2)√Ʌ is derived. The law of cosmological force makes it possible to obtain the extended law of universal gravitation. The extended law of universal gravitation includes two laws of gravitation: Newton's law of gravitation and the law of cosmological force. The extended law of universal gravitation does not have the limitations of Newton's law of gravitation. It describes the full force of gravitational interaction both on small scales and on the scale of the Universe. The coupling constants in the extended law of universal gravitation are two constants: the Newtonian constant of gravitation G and the cosmological constant Ʌ. The equation of the extended law of universal gravitation without using the gravitational constant G is given. The extended law of universal gravitation gives an explanation of the Galaxy rotation curve and the Pioneer anomaly. Extended Newtonian dynamics is able to provide solutions to the problems of astrophysics and cosmology without expecting (and instead of) quantum gravity.