This is the first full-length study of a Welsh family of the
thirteenth to fifteenth centuries who were not drawn from the
princely class. Though they were of obscure and modest origins, the
...patronage of great lords of the March - such as the Mortimers of
Wigmore or the de Bohun earls of Hereford - helped them to become
prominent in Wales and the March, and increasingly in England. They
helped to bring down anyone opposed by their patrons - like
Llywelyn, prince of Wales in the thirteenth century, or Edward II
in the 1320s. In the process, they sometimes faced great danger but
they contrived to prosper, and unusually for Welshmen one branch
became Marcher lords themselves. Another was prominent in Welsh and
English government, becoming diplomats and courtiers of English
kings, and over some five generations many achieved knighthood.
Their fascinating careers perhaps hint at a more open society than
is sometimes envisaged.
This is a review of the activities and successes of the 43rd residential JACT Latin Summer School, run in July 2023. Specifically, it covers our typical teaching arrangement, lectures, trips and ...events and acknowledges the generosity of our sponsors.
Sensitivity Analysis (SA) investigates how the variation in the output of a numerical model can be attributed to variations of its input factors. SA is increasingly being used in environmental ...modelling for a variety of purposes, including uncertainty assessment, model calibration and diagnostic evaluation, dominant control analysis and robust decision-making. In this paper we review the SA literature with the goal of providing: (i) a comprehensive view of SA approaches also in relation to other methodologies for model identification and application; (ii) a systematic classification of the most commonly used SA methods; (iii) practical guidelines for the application of SA. The paper aims at delivering an introduction to SA for non-specialist readers, as well as practical advice with best practice examples from the literature; and at stimulating the discussion within the community of SA developers and users regarding the setting of good practices and on defining priorities for future research.
•We present an overview of SA and its link to uncertainty analysis, model calibration and evaluation, robust decision-making.•We provide a systematic review of existing approaches, which can support users in the choice of an SA method.•We provide practical guidelines by developing a workflow for the application of SA and discuss critical choices.•We give best practice examples from the literature and highlight trends and gaps for future research.
This is a review of the activities and successes of the 42nd residential JACT Latin Summer School, run in July 2022. Specifically, it covers our typical teaching arrangement, lectures, trips and ...events and acknowledges the generosity of our sponsors.
The response of North Atlantic and European extratropical cyclones to climate change is investigated in the climate models participating in phase 5 of the Coupled Model Intercomparison Project ...(CMIP5). In contrast to previous multimodel studies, a feature-tracking algorithm is here applied to separately quantify the responses in the number, the wind intensity, and the precipitation intensity of extratropical cyclones. Moreover, a statistical framework is employed to formally assess the uncertainties in the multimodel projections. Under the midrange representative concentration pathway (RCP4.5) emission scenario, the December–February (DJF) response is characterized by a tripolar pattern over Europe, with an increase in the number of cyclones in central Europe and a decreased number in the Norwegian and Mediterranean Seas. The June–August (JJA) response is characterized by a reduction in the number of North Atlantic cyclones along the southern flank of the storm track. The total number of cyclones decreases in both DJF (−4%) and JJA (−2%). Classifying cyclones according to their intensity indicates a slight basinwide reduction in the number of cyclones associated with strong winds, but an increase in those associated with strong precipitation. However, in DJF, a slight increase in the number and intensity of cyclones associated with strong wind speeds is found over the United Kingdom and central Europe. The results are confirmed under the high-emission RCP8.5 scenario, where the signals tend to be larger. The sources of uncertainty in these projections are discussed.
An accurate assessment of liquid-phase mass transport resistances is necessary for understanding and optimizing battery performance using mathematical models. This work combines modeling and ...experiments to quantify tortuosity in electrolyte-filled porous battery structures (separator and active-material film). Tortuosities of separators were measured by two methods, AC impedance and polarization-interrupt, which produced consistent results. We measured an apparent interfacial resistance at the lithium metal electrodes that contributed to both ohmic and diffusional resistance of the cell. The polarization-interrupt experiment was used similarly to measure effective electrolyte transport in porous films of cathode materials, particularly films containing LiFePO
4. An empirical relationship between porosity and the tortuosity of the porous structures was developed. Our results demonstrate that the tortuosity-dependent mass transport resistance in porous separators and electrodes is significantly higher than that predicted by the oft-used Bruggeman relationship.
Allylindium halides are valuable allylating reagents, which can even be applied in aqueous solutions. Previous 1H NMR spectroscopic investigations suggested that these reagents are stable for several ...hours in D2O, whereas ESI-mass spectrometric experiments in H2O pointed to much shorter lifetimes. To resolve this seeming discrepancy, the present study systematically examines the solvolysis of allylindium iodide in H2O, D2O, and mixtures thereof by both analytical methods. Kinetic measurements find a large kinetic isotope effect (KIE = 12.0 ± 1.5 at 298 K), which fully explains the different behavior in H2O and D2O. Moreover, new intact and partially hydrolyzed allylindium intermediates are detected. Additional experiments on solutions of allylindium iodide in CH3OH, CH3OD, and EtOH observe ions identical or similar to those present in aqueous solutions, but determine a somewhat smaller kinetic isotope effect.
This study has developed a rigorous and efficient maximum likelihood method for estimating the parameters in stochastic energy balance models (with any k > 0 number of boxes) given time series of ...surface temperature and top-of-the-atmosphere net downward radiative flux. The method works by finding a state-space representation of the linear dynamic system and evaluating the likelihood recursively via the Kalman filter. Confidence intervals for estimated parameters are straightforward to construct in the maximum likelihood framework, and information criteria may be used to choose an optimal number of boxes for parsimonious k-box emulation of atmosphere–ocean general circulation models (AOGCMs). In addition to estimating model parameters the method enables hidden state estimation for the unobservable boxes corresponding to the deep ocean, and also enables noise filtering for observations of surface temperature. The feasibility, reliability, and performance of the proposed method are demonstrated in a simulation study. To obtain a set of optimal k-box emulators, models are fitted to the 4 × CO₂ step responses of 16 AOGCMs in CMIP5. It is found that for all 16 AOGCMs three boxes are required for optimal k-box emulation. The number of boxes k is found to influence, sometimes strongly, the impulse responses of the fitted models.
A positive trend in time has been noted in the seasonal amplitude of surface ocean pCO2 over much of the oceans, which is expected to have detrimental impacts on marine ecosystems. To determine ...whether or not this has an anthropogenic cause, this study investigates historical climate simulations from the Detection and Attribution Model Intercomparison Project with and without anthropogenic forcing. The simulations with anthropogenic forcing show clear evidence of positive trends, whereas the simulations with constant preindustrial atmospheric CO2 and natural external forcing give only negligible trends. A statistical analysis of five zonal latitudinal bands reveals that the trends detected over 1990–2014 in an ensemble of six observational products are attributable to anthropogenic forcing in mid‐latitudes (40°N–10°N, 10°S–40°S), while no trends are detected and modeled in the tropics and the Southern Ocean. Most models fail to represent the sign of the observed climatological mean seasonal cycle difference in high latitudes.
Plain Language Summary
Global warming due to fossil fuel use is unequivocal and documented by long records. In contrast, measurements for other important Earth system parameters are only available over recent decades. A short record length makes the attribution of observed trends to human‐induced forcing challenging. Trends may be hard to identify due to chaotic Earth system variability. The seasonal amplitude of the partial pressure of CO2 (pCO2) in the surface ocean is observed to increase, with global‐scale data available since 1990. A continued increase is expected to have negative impacts on fish as the amplified seasonality leads to very high pCO2, hindering the uptake of oxygen during breathing. Here, we analyze pCO2 from climate model historical simulations forced by human‐caused and natural factors versus simulations with natural factors only. The results allow us to firmly attribute the observed trend in the pCO2 seasonal amplitude in mid‐latitudes to human activities.
Key Points
Trends in seasonal amplitudes of surface ocean pCO2 are analyzed in observations and CMIP6 simulations with/without anthropogenic forcing
Applying an Analysis of Covariance, the observed trends in mid‐latitude regions are firmly attributed to anthropogenic forcing
The model ensemble shows large data‐model and model‐model discrepancies in the pCO2 seasonal cycle, in particular in high‐latitude regions
Statistical relationships between future and historical model runs in multimodel ensembles (MMEs) are increasingly exploited to make more constrained projections of climate change. However, such ...emergent constraints may be spurious and can arise because of shared (common) errors in a particular MME or because of overly influential models. This study assesses the robustness of emergent constraints used for Arctic warming by comparison of such constraints in ensembles generated by the two most recent Coupled Model Intercomparison Project (CMIP) experiments: CMIP3 and CMIP5. An ensemble regression approach is used to estimate emergent constraints in Arctic wintertime surface air temperature change over the twenty-first century under the Special Report on Emission Scenarios (SRES) A1B scenario in CMIP3 and the Representative Concentration Pathway (RCP) 4.5 scenario in CMIP5. To take account of different scenarios, this study focuses on polar amplification by using temperature responses at each grid point that are scaled by the global mean temperature response for each climate model. In most locations, the estimated emergent constraints are reassuringly similar in CMIP3 and CMIP5 and differences could have easily arisen from sampling variation. However, there is some indication that the emergent constraint and polar amplification is substantially larger in CMIP5 over the Sea of Okhotsk and the Bering Sea. Residual diagnostics identify one climate model in CMIP5 that has a notable influence on estimated emergent constraints over the Bering Sea and one in CMIP3 that that has a notable influence more widely along the sea ice edge and into midlatitudes over the western North Atlantic.
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