Radiative Forcing Research Articles

Fractional magnetohydrodynamic Casson fluid flow with thermal radiation and buoyancy effects: a constant proportional Caputo model

This research examines the magnetohydrodynamic (MHD) flow of a Casson flow over an oscillating vertically plate, incorporating thermal radiation and buoyancy effects using the constant proportional Caputo (CPC) fractional derivative. By introducing memory and nonlocal effects, the fractional derivative provides an enhanced framework for accurately capturing the coupled behavior of fluid dynamics, mass, and heat transfer. Applying the Laplace transform, the fractional partial differential equations that control the flow are transformed into ordinary differential equations, which are then solved numerically by Stehfest’s and Tzou’s techniques. This methodology enables detailed analysis of key physical parameters, such as magnetic fields, thermal radiation, and buoyant forces, on the velocity, temperature, and concentration distributions. Results reveal that the fractional parameter significantly refines the concentration, temperature, and velocity profiles, offering novel insights into the dynamics of MHD flows under thermal and concentration gradients. The model is validated against prior work, showing excellent agreement in limiting cases and confirming the robustness of the approach. The study’s findings are applicable to high temperature plasmas, nuclear reactor cooling systems, and power generation technologies, contributing an advanced analytical framework for exploring complex fluid dynamics in interdisciplinary engineering and physical contexts.

Quantifying both socioeconomic and climate uncertainty in coupled human–Earth systems analysis

Information about the likelihood of various outcomes is needed to inform discussions about climate mitigation and adaptation. Here we provide integrated, probabilistic socio-economic and climate projections, using estimates of probability distributions for key parameters in both human and Earth system components of a coupled model. We find that policy lowers the upper tail of temperature change more than the median. We also find that while human system uncertainties dominate uncertainty of radiative forcing, Earth system uncertainties contribute more than twice as much to temperature uncertainty in scenarios without fixed emissions paths, reflecting the uncertainty of translating radiative forcing into temperature. The combination of human and Earth system uncertainty is less than additive, illustrating the value of integrated modeling. Further, we find that policy costs are more uncertain in low- and middle-income economies, and that renewables are robust investments across a wide range of policies and socio-economic uncertainties.

Impact of Pitching on Infraspinatus Muscle Elasticity in High School Baseball Pitchers: A Continuous Shear Wave Elastography Study

Background/Objectives: The repetitive overhead throwing of baseball stresses the posterior shoulder, including the rotator cuff and capsule, causing stiffness, tissue thickening, and dysfunction. Previous studies on collegiate baseball players have linked these changes to glenohumeral internal rotation deficits, pain, and injuries. However, these studies primarily used acoustic radiation force impulse-based shear wave elastography (SWE), which has limitations, including tissue heating and lack of portability. The acute effects of pitching on infraspinatus (ISP) muscle elasticity in high school pitchers remain unclear. Therefore, this study aimed to evaluate the acute impact of pitching on ISP muscle elasticity in high school baseball pitchers using continuous SWE (C-SWE), which is a safer and more portable method. The relationship between ISP muscle elasticity and pitching load was also examined. Methods: ISP muscle shear wave velocity (SWV), shoulder range of motion, and strength were evaluated in high school baseball pitchers. The participants were categorized into pitching and non-pitching groups based on whether they pitched with full effort on the day of their medical checkup. C-SWE was used to assess ISP muscle elasticity. Results: The pitching group had considerably higher ISP muscle SWV on the dominant side than the non-pitching group (p = 0.008). A significant positive correlation was observed between pitch and ISP muscle SWV (r = 0.467, p = 0.003). Conclusions: Repetitive pitching acutely increases ISP muscle stiffness in high school pitchers, contributing to posterior shoulder tightness. C-SWE is a safe and practical method for assessing tissue elasticity and developing injury prevention strategies.

Speleothem evidence of solar modulation on the south Asia monsoon intensity

The influence of solar variation on climate has long been debated. Here, we utilize a decadal-resolved speleothem δ18O record from Vietnam, spanning 32.5 to 27.5 kyr BP, as a proxy for regional precipitation levels. Our results show a general coherence between Total Solar Irradiance (TSI) and regional precipitation, supporting a positive climate response consistent with conventional monsoon theory. Spectral analysis on studied datasets reveals an approximately 180-year periodicity coinciding with the de Vries cycle of solar activity. Further comparing our record with 35 other speleothem records, we demonstrate the importance of sufficient age control points in capturing solar-related periodicities. Model simulation shows that TSI could enhance monsoonal circulation and regional precipitation. Also highlighted are the implications of chronology control for detecting climate events in proxy records. The new findings underscore the significance of relatively minor radiative forcing in regional climate dynamics over monsoonal Asia on decadal to centennial timescales.

A rapid-application emissions-to-impacts tool for scenario assessment: Probabilistic Regional Impacts from Model patterns and Emissions (PRIME)

Abstract. Climate policies evolve quickly, and new scenarios designed around these policies are used to illustrate how they impact global mean temperatures using simple climate models (or climate emulators). Simple climate models are extremely efficient, although some can only provide global estimates of climate metrics such as mean surface temperature, CO2 concentration and effective radiative forcing. Within the Intergovernmental Panel on Climate Change (IPCC) framework, understanding of the regional impacts of scenarios that include the most recent science is needed to allow targeted policy decisions to be made quickly. To address this, we present PRIME (Probabilistic Regional Impacts from Model patterns and Emissions), a new flexible probabilistic framework which aims to provide an efficient mechanism to run new scenarios without the significant overheads of larger, more complex Earth system models (ESMs). PRIME provides the capability to include features of the most recent ESM projections, science and scenarios to run ensemble simulations on multi-centennial timescales and include analyses of many key variables that are relevant and important for impact assessments. We use a simple climate model to provide the global temperature response to emissions scenarios. These estimated temperatures are used to scale monthly mean patterns from a large number of CMIP6 ESMs. These patterns provide the inputs to a “weather generator” algorithm and a land surface model. The PRIME system thus generates an end-to-end estimate of the land surface impacts from the emissions scenarios. We test PRIME using known scenarios in the form of the shared socioeconomic pathways (SSPs), to demonstrate that our model reproduces the ESM climate responses to these scenarios. We show results for a range of scenarios: the SSP5–8.5 high-emissions scenario was used to define the patterns, and SSP1–2.6, a mitigation scenario with low emissions, and SSP5–3.4-OS, an overshoot scenario, were used as verification data. PRIME correctly represents the climate response (and spread) for these known scenarios, which gives us confidence our simulation framework will be useful for rapidly providing probabilistic spatially resolved information for novel climate scenarios, thereby substantially reducing the time between new scenarios being released and the availability of regional impact information.

Dipole pattern in aerosol-induced atmospheric warming trends over the Indian subcontinent in the last two decades

Abstract Understanding the patterns of aerosol-induced perturbation in radiation budget and its drivers is crucial in climate science. Here, we examined spatio-temporal trends in aerosol-induced atmospheric warming and the top-of-the-atmosphere (TOA) and surface cooling over the Indian Subcontinent under clear-sky and all-sky conditions using clouds and the earth’s radiant energy system data for the period 2000–2021. Overall, the regional mean TOA and surface cooling were found to increase by 0.06 W m−2 yr−1 and 0.09 W m−2 yr−1, respectively. Over the last two decades, the aerosol-induced atmospheric warming in all-sky conditions increased over the subcontinent landmass and outflow regions over the ocean while it declined over dust-dominated arid regions. This dipole pattern was driven by a combination of an overall increase in aerosol optical depth, a gradual increase in the fraction of scattering aerosols over the Indian landmass dominated by anthropogenic sources, a decline in dust loading over the arid sources. As a result, atmospheric warming efficiency declined in most parts of the Indian subcontinent. A comparative meta-analysis revealed that aerosol-induced atmospheric warming was over-estimated by the existing studies where aerosol direct radiative forcings were estimated by 1-D radiative transfer model utilizing modeled optical properties based on incomplete information about in-situ physico-chemical properties derived from ground-based measurements. Our analysis showed that TOA and surface cooling by aerosols were higher in clear-sky conditions relative to the actual all-sky condition by up to 11 W m−2 and 16 W m−2, respectively; therefore, atmospheric warming reported for clear-sky conditions would be biased high over the subcontinent. As India embarked on a clean air mission, changes in aerosol loading and its composition are expected to alter the dipole pattern further in the future, impacting the regional climate via dynamic feedback.

Surface Energy Balance Responses to Radiative Forcing in the Central Arctic From MOSAiC and Models

AbstractThe Arctic surface energy budget (SEB) couples the atmosphere with the sea ice, making it useful for both studying surface processes as well as evaluating models. Improved understanding of atmosphere‐ice interactions is required to improve models, requiring year‐round observations to address seasonally dependent biases. This work uses novel observations from the MOSAiC expedition to quantify the responses of surface fluxes to radiative forcing over sea ice throughout a complete annual cycle. We identify two primary regimes of flux response: an ice growth regime in winter and an ice melt regime in summer. In the growth regime, changes in radiative forcing impact upwelling longwave, sensible heat, and subsurface heat fluxes, whereas in the melt regime changes in radiative forcing primarily alter the amount of melt and subsurface transmission because the surface temperature is fixed. These observed responses of surface fluxes to radiative forcing are used to evaluate seven weather forecast models during the ice growth regime. In most models, the responses of surface fluxes to radiative forcing do not match observations. Many models also have biased downwelling longwave. One model (the Coupled Arctic Forecast System; CAFS) adequately captures both the mean radiative forcing and the flux responses in winter. CAFS is further evaluated against observations spanning the full MOSAiC year, demonstrating sufficient agreement to provide a more generalized understanding of these SEB process relationships across the Arctic.

Dust on Snow Radiative Forcing and Contribution to Melt in the Colorado River Basin

AbstractIn the mountainous headwaters of the Colorado River episodic dust deposition from adjacent arid and disturbed landscapes darkens snow and accelerates snowmelt, impacting basin hydrology. Patterns and impacts across the heterogenous landscape cannot be inferred from current in situ observations. To fill this gap daily remotely sensed retrievals of radiative forcing and contribution to melt were analyzed over the MODIS period of record (2001–2023) to quantify spatiotemporal impacts of snow darkening. Each season radiative forcing magnitudes were lowest in early spring and intensified as snowmelt progressed, with interannual variability in timing and magnitude of peak impact. Over the full record, radiative forcing was elevated in the first decade relative to the last decade. Snowmelt was accelerated in all years and impacts were most intense in the central to southern headwaters. The spatiotemporal patterns motivate further study to understand controls on variability and related perturbations to snow water resources.

Dust in the arctic: a brief review of feedbacks and interactions between climate change, aeolian dust and ecosystems

Climatic feedbacks and ecosystem impacts related to dust in the Arctic include direct radiative forcing (absorption and scattering), indirect radiative forcing (via clouds and cryosphere), semi-direct effects of dust on meteorological parameters, effects on atmospheric chemistry, as well as impacts on terrestrial, marine, freshwater, and cryospheric ecosystems. This review discusses our recent understanding on dust emissions and their long-range transport routes, deposition, and ecosystem effects in the Arctic. Furthermore, it demonstrates feedback mechanisms and interactions between climate change, atmospheric dust, and Arctic ecosystems.

Climate Forcing of Bioenergy Feedstocks: Insights From Carbon and Energy Flux Measurements

ABSTRACTBioenergy from biofuels has the potential to slow growing atmospheric carbon dioxide concentrations by reducing fossil fuel use. However, growing bioenergy feedstocks is a land‐intensive process. In the United States, the recent expansion of maize bioethanol has presented some environmental costs, prompting the development of several alternative bioenergy feedstocks. These feedstocks, selected in part for traits associated with ecosystem services, may provide opportunities for environmental benefits beyond fossil fuel displacement. We hypothesized that these bioenergy ecosystems will provide direct climatic cooling through their influence on carbon and radiative energy fluxes (i.e., through albedo). To test this hypothesis, we investigated the potential cooling effect of five current or potential bioenergy feedstocks using multi‐year records from eddy covariance towers. Perennial feedstocks were carbon sinks, with an annual mean net ecosystem carbon balance (NECB) of −2.7 ± 2.1 Mg C ha−1 for miscanthus, −0.8 ± 1.1 Mg C ha−1 for switchgrass, and −1.4 ± 0.7 Mg C ha−1 for prairie. In contrast, annual rotations were generally carbon sources, with an annual mean NECB of 2.6 ± 2.4 Mg C ha−1 for maize‐soy and 3.2 ± 2.1 Mg C ha−1 for sorghum‐soy. Using maize‐soy as a baseline, conversion to alternative feedstocks increased albedo, inducing further cooling. This effect was strongest for miscanthus, with −3.5 ± 2.0 W m−2 of radiative forcing, and weakest for sorghum, with −1.4 ± 1.4 W m−2. When feedstock effects on carbon and albedo were compared using carbon equivalents, carbon fluxes were the stronger ecosystem effect, underscoring the role of perennial species as effective carbon sinks. This work highlights the impact of feedstock choice on ecosystem processes as an element of bioenergy land conversion strategies.

Factors limiting contrail detection in satellite imagery

Abstract. Contrails (ice clouds, originally line-shaped after initiation by aircraft exhaust) provide a significant warming contribution to the overall climate impact of aviation. This makes reducing them a key target for future climate strategies in the sector. Identifying pathways for contrail reduction requires accurate models of contrail formation and life cycle, which in turn need suitable observations to constrain them. Infrared imagers on geostationary satellites provide widespread contrail observations, with sufficient time resolution to observe the evolution of their properties. However, contrails are often narrow and optically thin, which makes them challenging for satellites to identify. Quantifying the impact of contrail properties on observability is essential to determine the extent to which satellite observations can be used to constrain contrail models and to assess the climate impact of aviation. In this work, contrail observability is tested by applying a simple contrail detection algorithm to synthetic images of linear contrails in an otherwise clear sky against a homogeneous ocean background. Only (46±2) % of a modelled population of global contrail segments is found to be observable using current 2 km resolution satellite-borne imagers, even in this maximally observable case. By estimating the radiative forcing of individually modelled contrails, it is found that a significantly higher portion of contrail forcing is detectable using the same 2 km resolution imager – (72±2) % of instantaneous long-wave (LW) forcing – because more easily observable contrails have a larger climate impact. This detection efficiency could be partly improved by using a higher-resolution infrared imager, which would also allow contrails to be detected earlier in their life cycle. However, even this instrument would still miss the large fraction of contrails that are too optically thin to be detected. These results support the use of contrail detection and lifetime observations from existing satellite imagers to draw conclusions about the relative radiative importance of different contrails under near-ideal conditions. However, there is a highlighted need to assess the observability of contrails where the observation conditions may vary by application. These observability factors are shown to change in response to climate action, demonstrating a need to consider the properties of the observing system when assessing the impacts of proposed mitigation strategies.

Fingerprints of El Niño-Southern Oscillation and solar activity cycles recorded in the middle Eocene Bohai Bay Basin (East China)

The behavior of the global climate system on scales from years to centuries is related to several mechanisms, including solar forcing and the El Niño-Southern Oscillation (ENSO). However, due to limited stratigraphic resolution and the accuracy of dating methods, pre-Quaternary archives are rare. A middle Eocene lacustrine shale in the Bohai Bay Basin of East China contains annual laminae which provides a site to study the astronomical and varve chronology of the basin. Principal component analysis of the sediments in the cored material, their magnetic susceptibility and grayscale scans as well as analysis of the varve thickness in thin sections, jointly reveal variations between a warm/dry and cold/wet climate on the scale of centuries (∼200−240 years and ∼350 years, respectively), probably corresponding with cycles in solar activity. In situ δ13C and δ18O values of the light carbonate laminae indicate, in combination with varve-thickness data, that algal blooming and carbonate production occurred at ∼2.1−8.7-year cycles, which could be ascribed to ENSO activity. Our finding of the ENSO variability during this notably warm interval indicates that evident interannual variability will likely continue to exist in our future greenhouse planet.

Significant Plasma Density Depletion From High‐ to Mid‐Latitude Ionosphere During the Super Storm in May 2024

AbstractWe demonstrate the global response of the ionosphere to the geomagnetic super storm on 10–11 May 2024. The in situ observations from the Swarm spacecraft show a rapid depletion of plasma density in the dawn and dusk sectors following the storm. The in situ data are further complemented by the ground‐based total electron content maps. Both the in situ and the ground‐based observations show significant depletion of electron density during the super storm in regions above 50° magnetic latitude. The density depletion originates from a polar hole in the morning high latitude sector. It is suggested that the strong convection speed under substantial solar wind forcing leads to chemical composition changes and rapid recombination in the ionosphere. The region of depleted plasma density is not confined to the polar cap but expands to auroral and mid‐latitude regions. The depleted plasma density lasts for about 3 days before it recovers to the pre‐storm levels.

Assessment of light absorbing carbonaceous aerosol and its absorption properties from forest fire in Himalayan Critical Zone Observatory.

Assessment of light absorbing carbonaceous aerosol and its absorption properties from forest fire in Himalayan Critical Zone Observatory.

Radiative forcing and vertical heating rate of dust aerosols in southwestern Tajikistan during summer 2023

Radiative forcing and vertical heating rate of dust aerosols in southwestern Tajikistan during summer 2023

Radiative warming by multicomponent soot-dominated aerosols can be controlled by material configuration.

Radiative warming by multicomponent soot-dominated aerosols can be controlled by material configuration.

An Idealized Parameter Study of Destabilization and Convection Initiation in Coastal Regions. Part I: Calm or Offshore Synoptic-Scale Flow

Abstract The influence of large bodies of water on convection initiation (CI) and the environment in which convection evolves is highly complex due to the wide range of parameters that control relevant processes. A substantial focus of sea-breeze front (SBF) CI research has focused on the role of mesoscale boundary or organized boundary layer circulation interactions with SBFs; however, less research has focused on heterogeneities in convective parameters and how those may affect CI coverage, timing, and location. In this two-part series, the authors present a parameter study of SBF CI through Cloud Model 1 (CM1) large-eddy simulations across a parameter space varying the cross-shore wind component and radiative forcing and water surface temperatures consistent with June, July, and August in the Great Lakes region. In Part I of this series, simulations under conditions of calm, weak, and moderate offshore flow (0, −2.5, and −5.0 m s−1) are presented. CI occurred in all calm simulations, with decreased coverage and frequency of CI in weak offshore flow. CI was least frequent during moderate offshore flow, despite stronger convergence, due to a shear profile that favored undercutting by the SBF under conditions of moderate offshore flow. Surface-based convective available potential energy (SBCAPE) maxima developed on the cool side of the SBF, with convection occurring on the cool side of the SBF in some cases. Analyses are presented with a focus on the nature of the SBF, distribution of convective parameters, and their implications on CI.

Dependence of acoustophoretic aggregation on the impedance of microchannel's walls

Dependence of acoustophoretic aggregation on the impedance of microchannel's walls

Pressure sub-node formation by interparticle acoustic radiation forces

Microscale manipulation is essential for advancing research in biophysics and biomedical engineering, with acoustic tweezers emerging as a powerful tool for non-contact and label-free particle manipulation. Despite significant progress in understanding acoustic forces on individual objects, the collective behavior of particles in confined acoustic fields remains insufficiently explored. In this study, we experimentally investigate the acoustic trapping forces acting on microscale particles (2–5 μm) commonly used for cellular and organelle micromanipulation. Using a custom-designed acoustic device, featuring an aluminum mold and opposing piezoelectric transducers, we generate a standing wave field to analyze particle trapping dynamics. Our results reveal that, as particle concentration increases, interparticle interactions critically influence pressure nodal patterning, leading to the emergence of previously unreported “pressure sub-nodes” parallel to the primary nodal planes. This novel finding challenges conventional assumptions of acoustic trapping by demonstrating that equilibrium particle configurations are not only dictated by external acoustic pressure gradients but also by particle-induced secondary forces. We provide a theoretical and experimental analysis of these forces, offering new insights into the fundamental mechanisms governing acoustic manipulation. By elucidating the interplay between acoustic radiation and interparticle forces, our work advances the understanding of acoustic manipulation, highlighting the impact of acoustic-mediated forces on node patterning, and paving the way for enhanced control in biophysical and biomedical applications.

Entropy analysis in tri-hybrid nanofluid flow past a curved surface with applications of heat radiation and Lorentz force; numerical simulation

Entropy analysis in tri-hybrid nanofluid flow past a curved surface with applications of heat radiation and Lorentz force; numerical simulation