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ReportKimutai J, Barnes C, Zachariah M, et al., 2023,
Human-induced climate change increased drought severity in Horn of Africa
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Journal articleTang XY, Yang WW, Ma X, et al., 2023,
An integrated modeling method for membrane reactors and optimization study of operating conditions
, Energy, Vol: 268, ISSN: 0360-5442This study proposes an integrated membrane reactor modeling method based on thermodynamic equilibrium to investigate the enhancement potential of membrane reactors relative to original reactors. The modeling method is implemented by MATLAB codes, where local reaction equilibrium is calculated by the minimum Gibbs free energy principle, and product separation is determined by iterative convergence. Combined with the developed and validated methane membrane reforming reactor model, the reaction operating conditions are parametrically analyzed and optimized by GA and NSGA-II. The results show that pressure-driven hydrogen recovery enhancement is the key to improving membrane reactor performance. The reference reaction conditions given by the NSGA-II decision method are similar to those given by GA, concentrated in a temperature range of 702.5–952.0 K, a pressure range of 805.7–1077.8 kPa, and a steam-to-methane ratio range of 1.2–9.9. The membrane reactor has the potential to achieve a hydrogen yield ratio of 4.0 and an outlet hydrogen molar fraction of 79.7% simultaneously at low temperature and high pressure, which is unachievable in the original reactor. Furthermore, the Pareto solution set of reactor performance obtained by NSGA-II provides the reference for the theoretical design of reactors and their systems.
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Journal articleQuilodran-Casas C, Arcucci R, 2023,
A data-driven adversarial machine learning for 3D surrogates of unstructured computational fluid dynamic simulations
, PHYSICA A-STATISTICAL MECHANICS AND ITS APPLICATIONS, Vol: 615, ISSN: 0378-4371- Cite
- Citations: 4
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Journal articleOluleye O, Bishay D, Kas B, 2023,
Can a hierarchical ordering of alternative technological concepts for decarbonizing industrial energy systems minimize mitigation costs?
, Frontiers in Sustainability, Vol: 4, Pages: 1-15, ISSN: 2673-4524Integration of alternative technological concepts such as switching to alternative fuels, advanced energy efficiency, and carbon capture & storage in existing industrial energy systems can prove highly effective at minimising emissions; however, their adoption is low since solutions using these concepts raise costs considerably. The hypothesis of this work is a hierarchical combination of these concepts can reduce mitigation cost. To this end a mixed method approach is applied combining energy simulation with a novel Mixed Integer Linear Programming model developed to explore 48 alternative solutions to make industrial energy systems more sustainable. The method was applied to the most common industrial energy systems configurations. Results show that the added cost of integrating alternative technological concepts are lowered when energy efficiency via direct heat recovery is explored first in an optimisation-based hierarchy of options. The hierarchy is advanced energy efficiency before fuel and technology switching or integrating carbon capture and storage. This means process integration can pay for steeper reductions in carbon emissions. Integrating alternative technological concepts optimally and hierarchically reduced emissions by 61%, and costs by 55.7% compared to a partial integration for a heat-only business-as-usual industrial energy systems. Even though switching to an alternative fuel (blue hydrogen) reduces carbon emissions by 72%, costs increase by at least 3% compared to a system using fuel gas and fuel oil. A hierarchical integration of blue hydrogen reduces cost by 47% and carbon emissions by 88.7%. Partial integration of carbon capture and storage reduces carbon emissions by 36% but costs increase by 89%, with full integration using optimisation and the hierarchy costs only increase by 6.3%. therefore, the cost-effectiveness of integrating alternative technological concepts is highly influenced by the hierarchy which seeks to minimise demand fo
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ReportPreston-Allen R, Albini D, Barron L, et al., 2023,
Are urban areas hotspots for pollution from pet parasiticides?
, Are urban areas hotspots for pollution from pet parasiticides?, www.imperial.ac.uk/grantham, Publisher: Grantham Institute, Briefing Note 15This briefing considers the environmental impact of pet parasiticides, which are commonly used to kill parasites such as fleas and ticks. It reviews possible routes that chemicals from veterinary parasiticides enter the environment, what impacts they may have on natural ecosystems and how to balance the needs of domestic pets, people, and the environment.
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Journal articleLai T-K, Toumi R, 2023,
Has there been a recent shallowing of tropical cyclones?
, Geophysical Research Letters, Vol: 50, Pages: 1-9, ISSN: 0094-8276Many aspects of tropical cyclone (TC) properties at the surface have been changing but any systematic vertical changes are unknown. Here, we document a recent trend of high thick clouds of TCs. The global inner-core high thick cloud fraction measured by satellite has decreased from 2002 to 2021 by about 10% per decade. The TC inner-core surface rain rate is also found to have decreased during the same period by a similar percentage. This suppression of high thick clouds and rain has been largest during the intensification phase of the strongest TCs. Hence, these two independent and consistent observations suggest that the TC inner-core convection has weakened and that TCs have become shallower recently at least. For this period, the lifetime maximum intensity of major TCs has not changed and this suggests an increased efficiency of the spin-up of TCs.
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ReportSheehan C, Green T, 2023,
Kenya Charging Forward: A brief assessment of Kenya’s e-mobility policy landscape and proposed changes
, Publisher: Energy Futures LabThe transport sector’s share of Kenya’s total greenhouse gas (GHG)emissions has been projected to grow from 11% in 2015 to 14.7%by 2030 in a business as usual (BAU) scenario [1]. In line with theKenyan Government’s goal of reducing total GHG emissions by 32%relative to BAU in 2030 [2], it has begun several initiatives to startmitigating its transport emissions, including opportunities relatedto growing its nascent e-mobility sector. The private sector, with arange of around 25 new e-mobility companies [3], has been providingsolutions through the supply of various electric vehicles aimed atserving the local market, while also leading the way in deployingcharging and battery swapping infrastructure.
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ReportOtto F, Zachariah M, Barnes C, 2023,
The role of climate change in extreme rainfall associated with Cyclone Gabrielle over Aotearoa New Zealand’s East Coast
, The role of climate change in extreme rainfall associated with Cyclone Gabrielle over Aotearoa New Zealand’s East Coast -
ReportHalkyard S, Levey S, Amer H, et al., 2023,
Grantham Institute Outlook 2022-2023
, Grantham Institute Outlook 2022-2023, www.imperial.ac.uk/grantham, Publisher: Grantham InstituteThe Grantham Institute Outlook magazine provides an overview of the climate and environmental research underway at Imperial College London, encompassing both recent achievements and future plans.
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ReportHarrington LJ, Dean SM, Awatere S, et al., 2023,
The role of climate change in extreme rainfall associated with Cyclone Gabrielle over Aotearoa New Zealand’s East Coast
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Journal articleTong Z, Liu H, Cao XE, et al., 2023,
Cavitation diagnosis for water distribution pumps: An early-stage approach combing vibration signal-based neural network with high-speed photography
, Sustainable Energy Technologies and Assessments, Vol: 55, ISSN: 2213-1388As an essential component of municipal water distribution systems, centrifugal water pumps are of great significance to achieve urban sustainability. Cavitation is a common phenomenon in water pumps that cause energy inefficiency and mechanical failures. To prevent cavitation damages, an early-stage cavitation diagnosis approach combing vibration signal-based neural network with high-speed photography was proposed. An adaptive neural network was developed using vibration measurement and cavitation states predefined using high-speed cavitation images collected at an in-house laboratory pump system with transparent casings. The correlation among synchronized cavitation images, vibration signals and pump performance was investigated. Our analysis shows that the head-drop detection method commonly used in the industry greatly underestimated the damage of cavitation with the fact that a 3% head drop corresponded to a cavitation intensity of 42.1%. Both the number of predefined cavitation states for training and the structure of neural networks greatly affected diagnosis accuracy and computing load. A two-stage ANN structure with eight cavitation states displayed the best performance with a much faster training speed compared with common shallow learning methods and consistent diagnosis accuracy of over 95% in real time. A water-energy-carbon nexus model was built to demonstrate provincial energy-saving potentials associated with cavitation prevention in China.
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Journal articleCao XE, Ngetich GC, 2023,
The need to normalize failure.
, Nat Rev Chem, Vol: 7, Pages: 69-70 -
Journal articleLiu L, Zhou Z, Cao XE, et al., 2023,
Screening of optimal dopants on cobalt-based ceramics for high-temperature thermochemical energy storage
, Ceramics International, Vol: 49, Pages: 2329-2339, ISSN: 0272-8842To date, numerous dopants have been investigated to promote the initial heat storage performance or sintering resistance of Co<inf>3</inf>O<inf>4</inf> for thermochemical energy storage. Owing to the different synthesis methods and heat storage test conditions, the performances of these materials are not comparable. In this work, nine dopants, including four unreported dopants, were systematically compared and screened under the same conditions. Results demonstrated that for five redox cycles, the Si- and Mg- doped sample had adverse effects on the conversion rate, and the others maintained the conversion rate above 0.95. Cu and Zr doping exhibited the highest re-oxidation rate values, and those of the others were lower than that of pure cobalt oxide. Moreover, except for Cu and Zr, all dopants adversely affected energy density. According to aforementioned heat storage properties, Cu-, Zr-doped samples, and pure cobalt oxide were subjected to 100 cycles for further comparison. The Cu-doped sample exhibited a higher re-oxidation rate and energy density, and the Zr-doped sample exhibited more stable cyclability. Finally, by doping Cu and Zr, the micromorphology evolution was more stable than that of pure oxide for multiple cycles, and X-ray photoelectron spectroscopy results revealed that the higher surface oxygen was the primary reason for the superior performance facilitated by Cu and Zr. The Cu- and Zr-modified cobalt oxides were the potential candidates for thermochemical energy storage.
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Journal articleRiou J, Hauser A, Althaus C, et al., 2023,
Direct and indirect effects of the COVID-19 pandemic on mortality in Switzerland
, Nature Communications, Vol: 14, ISSN: 2041-1723The direct and indirect impact of the COVID-19 pandemic on population-level mortality is of concern to public health but challenging to quantify. Using data for 2011–2019, we applied Bayesian models to predict the expected number of deaths in Switzerland and compared them with laboratory-confirmed COVID-19 deaths from February 2020 to April 2022 (study period). We estimated that COVID-19-related mortality was underestimated by a factor of 0.72 (95% credible interval [CrI]: 0.46–0.78). After accounting for COVID-19 deaths, the observed mortality was −4% (95% CrI: −8 to 0) lower than expected. The deficit in mortality was concentrated in age groups 40–59 (−12%, 95%CrI: −19 to −5) and 60–69 (−8%, 95%CrI: −15 to −2). Although COVID-19 control measures may have negative effects, after subtracting COVID-19 deaths, there were fewer deaths in Switzerland during the pandemic than expected, suggesting that any negative effects of control measures were offset by the positive effects. These results have important implications for the ongoing debate about the appropriateness of COVID-19 control measures.
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Book chapterRao RR, van den Bosch ICG, Baeumer C, 2023,
Operando X-ray characterization of interfacial charge transfer and structural rearrangements
, Encyclopedia of Solid Liquid InterfacesKey technologies in energy conversion and storage, sensing and chemical synthesis rely on a detailed knowledge about charge transfer processes at electrified solid–liquid interfaces. However, these interfaces continuously evolve as a function of applied potentials, ionic concentrations and time. We therefore need to characterize chemical composition, atomic arrangement and electronic structure of both the liquid and the solid side of the interface under operating conditions. In this chapter, we discuss the state-of-the-art X-ray based spectroscopy and diffraction approaches for such “operando” characterization. We highlight recent examples from literature and demonstrate how X-ray absorption spectroscopy, X-ray photoelectron spectroscopy and surface X-ray diffraction can reveal the required interface-sensitive information.
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Book chapterHolm DD, Hu R, Street OD, 2023,
Coupling of waves to sea surface currents via horizontal density gradients
, Stochastic Transport in Upper Ocean Dynamics(STUOD 2021), Editors: Chapron, Memin, Crisan, Holm, Radomska, Publisher: Springer, Cham, Pages: 109-133, ISBN: 978-3-031-18988-3The mathematical models and numerical simulations reported here are motivated by satellite observations of horizontal gradients of sea surface temperature and salinity that are closely coordinated with the slowly varying envelope of the rapidly oscillating waves. This coordination of gradients of fluid material properties with wave envelopes tends to occur when strong horizontal buoyancy gradients are present. The nonlinear models of this coordinated movement presented here may provide future opportunities for the optimal design of satellite imagery that could simultaneously capture the dynamics of both waves and currents directly.The model derived here appears in two levels of approximation: first for rapidly oscillating waves, and then for their slowly varying envelope (SVE) approximation obtained by using the WKB approach. The WKB wave-current-buoyancy interaction model derived here for a free surface with significant horizontal buoyancy gradients indicates that the mechanism for the emergence of these correlations is the ponderomotive force of the slowly varying envelope of rapidly oscillating waves acting on the surface currents via the horizontal buoyancy gradient. In this model, the buoyancy gradient appears explicitly in the WKB wave momentum, which in turn generates density-weighted potential vorticity whenever the buoyancy gradient is not aligned with the wave-envelope gradient.
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Journal articleGangopadhyay A, Seshadri AK, Toumi R, 2023,
Beneficial role of diurnal smoothing for grid integration of wind power
, Environmental Research Letters, Vol: 18, ISSN: 1748-9326Smoothing of generation variability, i.e. reduction of variance in the aggregate generation is crucialfor grid integration of large-scale wind power plants. Prior studies of smoothing have focused ongeographical smoothing, based on distance. In contrast, we propose a novel concept ‘diurnalsmoothing’ that depends on spatial variations in the timing of seasonal-mean diurnal cycle peak.Considering the case of India, which experiences a strong diurnal cycle of wind-speed, we showhow spatial heterogeneity in the wind diurnal cycle can be exploited to smooth wind powervariability over and above geographical smoothing. For any given separation distance betweensites, the hourly wind speed correlation is highly variable. Difference in timing of the diurnal cyclepeak is an important factor for explaining this variability and we define smoothing from differentlytimed seasonal-mean diurnal cycle as ‘diurnal smoothing’. We show that apart from separationdistance, the diurnal cycle is crucial for correlation among sites separated by 200 km or more withstrong diurnal cycles (amplitude more than approximately 0.5 m s−1). Thus, diurnal smoothing isa vital factor in the aggregation of large wind power plants, and grid integration is benefited byconsidering (in addition to distance) new wind plant sites with largely separated diurnal cycles,especially those differing by roughly 12 h. Such diurnal smoothing is relevant for regions across theworld with strong wind speed diurnal cycles. Ultimately grid integration depends on variations intotal wind and solar generation and demand. Hence, their combined effects must be studied.
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Journal articleTheokritoff E, Thomas A, Lissner T, et al., 2023,
Interacting adaptation constraints in the Caribbean highlight the importance of sustained adaptation finance
, CLIMATE RISK MANAGEMENT, Vol: 39, ISSN: 2212-0963 -
Journal articleGong H, Cheng S, Chen Z, et al., 2022,
An efficient digital twin based on machine learning SVD autoencoder and generalised latent assimilation for nuclear reactor physics
, ANNALS OF NUCLEAR ENERGY, Vol: 179, ISSN: 0306-4549- Cite
- Citations: 47
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ReportBaker W, Acha S, Jennings N, et al., 2022,
Decarbonisation of buildings: Insights from across Europe
, Decarbonisation of buildings: Insights from across Europe, Publisher: The Grantham InstituteThis report considers four key challenges facing the UK in reducing carbon emissions from its building stock, and shares insights from across Europe that have the potential to help the UK to decarbonise and increase the energy efficiency of its buildings.
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Journal articleMurguía Burton ZF, Cao XE, 2022,
Let graduate students do internships
, Matter, Vol: 5, Pages: 4100-4104, ISSN: 2590-2393We discuss why graduate students should not only be allowed, but should be actively encouraged to pursue internships during graduate school. We speak with five scientists who interned during graduate school and share their stories and reflections. In closing, we offer suggestions for how institutions can and should support graduate students pursuing internship experiences.
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ReportRhodes A, Heptonstall P, Speirs J, 2022,
Materials for Energy - An Energy Futures Lab and UKERC Briefing Paper
, Publisher: Energy Futures LabThe transition to Net Zero will require substantial quantities of criticalmaterials in order to build and maintain new technologies, from renewablegeneration to batteries for electric vehicles. Materials such as lithiumwill be required in much larger quantities than before, while novelmaterials may need to be developed to replace expensive or scarceconventional materials. This Briefing Paper considers the current availability and development of materials for the energy sector, investigating both current availability and forecasted production of several critical materials and looking at the state of development of novel materials in the energy sector. Four materials considered critical to new energy technologies and the low-carbon transition were investigated for availability based on known reserves and projected future demand: lithium, cobalt, tellurium and copper. These materials were selected to illustrate the key themes that relate to concerns over the demand and supply of those metals and other materials that will be required for the transition to a global low-carbon energy system.
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ReportArnell N, Jonsson G, Oliver T, et al., 2022,
Climate Change, ecosystem impacts and systemic risk
, Climate Change, ecosystem impacts and systemic riskThis report highlights some of the vital dependencies of human societies on ecosystems, the damages that can occur from them as a result of climate change, and the steps required to better understand and characterise the systemic risks to societies that result from such climate change-driven ecosystem damages.
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Journal articleLuo H, Yukuhiro VY, Fernandez PS, et al., 2022,
Role of Ni in PtNi bimetallic electrocatalysts for hydrogen and value-added chemicals coproduction via glycerol electrooxidation
, ACS Catalysis, Vol: 12, Pages: 14492-14506, ISSN: 2155-5435Pt-based bimetallic electrocatalysts are promising candidates to convert surplus glycerol from the biodiesel industry to value-added chemicals and coproduce hydrogen. It is expected that the nature and content of the elements in the bimetallic catalyst can not only affect the reaction kinetics but also influence the product selectivity, providing a way to increase the yield of the desired products. Hence, in this work, we investigate the electrochemical oxidation of glycerol on a series of PtNi nanoparticles with increasing Ni content using a combination of physicochemical structural analysis, electrochemical measurements, operando spectroscopic techniques, and advanced product characterizations. With a moderate Ni content and a homogenously alloyed bimetallic Pt–Ni structure, the PtNi2 catalyst displayed the highest reaction activity among all materials studied in this work. In situ FTIR data show that PtNi2 can activate the glycerol molecule at a more negative potential (0.4 VRHE) than the other PtNi catalysts. In addition, its surface can effectively catalyze the complete C–C bond cleavage, resulting in lower CO poisoning and higher stability. Operando X-ray absorption spectroscopy and UV–vis spectroscopy suggest that glycerol adsorbs strongly onto surface Ni(OH)x sites, preventing their oxidation and activation of oxygen or hydroxyl from water. As such, we propose that the role of Ni in PtNi toward glycerol oxidation is to tailor the electronic structure of the pure Pt sites rather than a bifunctional mechanism. Our experiments provide guidance for the development of bimetallic catalysts toward highly efficient, selective, and stable glycerol oxidation reactions.
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Journal articlePeng J, Schwalbe-Koda D, Akkiraju K, et al., 2022,
Human- and machine-centred designs of molecules and materials for sustainability and decarbonization
, NATURE REVIEWS MATERIALS, Vol: 7, Pages: 991-1009, ISSN: 2058-8437- Cite
- Citations: 91
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Journal articleCrisan D, Street OD, 2022,
On the analytical aspects of inertial particle motion
, Journal of Mathematical Analysis and Applications, Vol: 516, Pages: 1-30, ISSN: 0022-247XIn their seminal 1983 paper, M. Maxey and J. Riley introduced an equation for the motion of a sphere through a fluid. Since this equation features the Basset history integral, the popularity of this equation has broadened the use of a certain form of fractional differential equation to study inertial particle motion. In this paper, we give a comprehensive theoretical analysis of the Maxey-Riley equation. In particular, we build on previous local in time existence and uniqueness results to prove that solutions of the Maxey-Riley equation are global in time. In doing so, we also prove that the notion of a maximal solution extends to this equation. We furthermore prove conditions under which solutions are differentiable at the initial time. By considering the derivative of the solution with respect to the initial conditions, we perform a sensitivity analysis and demonstrate that two inertial trajectories can not meet, as well as provide a control on the growth of the distance between a pair of inertial particles. The properties we prove here for the Maxey-Riley equations are also possessed, mutatis mutandis, by a broader class of fractional differential equations of a similar form.
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Journal articleLi Y, Tang Y, Toumi R, et al., 2022,
Revisiting the definition of rapid intensification of tropical cyclones by clustering the initial intensity and inner-core size
, Journal of Geophysical Research: Atmospheres, Vol: 127, ISSN: 2169-8996Rapid intensification (RI) of tropical cyclones (TCs) provides a great challenge in operational forecasting and contributes significantly to the development of major TCs. RI is commonly defined as an increase in the maximum sustained surface wind speed of at least a certain threshold within 24 hr. The most widely used threshold is 30 kt (15.4 m/s), which was determined statistically. Here we propose a new definition for RI by objectively clustering TCs using the intensification rate, initial intensity, and radius of the maximum wind speed (RMW). A group of 770 samples is separated at a threshold of 45 kt (23.2 m/s). The threshold is 40 kt (20.6 m/s) for the western North Atlantic, where TC size measurements are more reliable. Monte Carlo experiments demonstrate that the proposed threshold is robust even considering the uncertainty in RMW of as high as 30 km. We show that, when a TC undergoes RI, its maximum wind speed is approximately 60 ± 15 kt (30.9 ± 7.7 m/s) and the RMW is 45 ± 20 km. The new threshold outperforms the conventional threshold of 30 kt/24 hr in describing the bimodal distribution of lifetime maximum intensity and explaining the annual count of Category 5 TCs. This new definition provides a more physically based threshold and describes a more reliable representation of extreme events. Although more comparisons are needed for operational application, it is likely to be desirable for case-based process studies and could provide a more valuable metric for TC intensification classification and research.
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ReportJonsson G, Purvis A, 2022,
The interactions between biodiversity and climate change and the actions required to tackle both issues simultaneously and synergistically
, The interactions between biodiversity and climate change and the actions required to tackle both issues simultaneously and synergistically, https://www.imperial.ac.uk/grantham, Publisher: Grantham Institute, 38This briefing paper considers the relationship between the biodiversity and climate crises, the interactions between them, and why an integrated approach is essential to creating a sustainable future where people and planet can thrive.
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Journal articleTheokritoff E, D'haen SAL, 2022,
How is science making its way into national climate change adaptation policy? Insights from Burkina Faso
, CLIMATE AND DEVELOPMENT, Vol: 14, Pages: 857-865, ISSN: 1756-5529- Cite
- Citations: 10
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Journal articleSparks N, Toumi R, 2022,
The dependence of tropical cyclone pressure tendency on size
, Geophysical Research Letters, Vol: 49, ISSN: 0094-8276Current theories of tropical cyclone (TC) intensification give little direct indication of the role of the TC size in intensity changes, although there are observations showing a relationship. We develop a new model of TC central pressure tendency where the pressure change can be expressed as exponential with a time constant determined by the ratio of radius maximum wind (Rmax) and the column inflow or outflow speed. An analysis of observations confirms the relationship which becomes more important for a larger pressure tendency and suggests an upper bound on pressure tendency for a given Rmax. The dependence of the pressure tendency on size poses a challenging constraint on the accurate forecasting of TCs in numerical weather prediction and climate models.
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