Journal articles: 'Atmospheric circulation Mathematics'

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Hsia, Chun-Hsiung, Chang-Shou Lin, Tian Ma, and Shouhong Wang. "Tropical atmospheric circulations with humidity effects." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 471, no. 2173 (January 2015): 20140353. http://dx.doi.org/10.1098/rspa.2014.0353.

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The main objective of this article is to study the effect of the moisture on the planetary scale atmospheric circulation over the tropics. The modelling we adopt is the Boussinesq equations coupled with a diffusive equation of humidity, and the humidity-dependent heat source is modelled by a linear approximation of the humidity. The rigorous mathematical analysis is carried out using the dynamic transition theory. In particular, we obtain mixed transitions, also known as random transitions, as described in Ma & Wang (2010 Discrete Contin. Dyn. Syst. 26 , 1399–1417. ( doi:10.3934/dcds.2010.26.1399 ); 2011 Adv. Atmos. Sci. 28 , 612–622. ( doi:10.1007/s00376-010-9089-0 )). The analysis also indicates the need to include turbulent friction terms in the model to obtain correct convection scales for the large-scale tropical atmospheric circulations, leading in particular to the right critical temperature gradient and the length scale for the Walker circulation. In short, the analysis shows that the effect of moisture lowers the magnitude of the critical thermal Rayleigh number and does not change the essential characteristics of dynamical behaviour of the system.

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Proshutinsky, Andrey, Dmitry Dukhovskoy, Mary-Louise Timmermans, Richard Krishfield, and Jonathan L. Bamber. "Arctic circulation regimes." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 373, no. 2052 (October 13, 2015): 20140160. http://dx.doi.org/10.1098/rsta.2014.0160.

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Between 1948 and 1996, mean annual environmental parameters in the Arctic experienced a well-pronounced decadal variability with two basic circulation patterns: cyclonic and anticyclonic alternating at 5 to 7 year intervals. During cyclonic regimes, low sea-level atmospheric pressure (SLP) dominated over the Arctic Ocean driving sea ice and the upper ocean counterclockwise; the Arctic atmosphere was relatively warm and humid, and freshwater flux from the Arctic Ocean towards the subarctic seas was intensified. By contrast, during anticylonic circulation regimes, high SLP dominated driving sea ice and the upper ocean clockwise. Meanwhile, the atmosphere was cold and dry and the freshwater flux from the Arctic to the subarctic seas was reduced. Since 1997, however, the Arctic system has been under the influence of an anticyclonic circulation regime (17 years) with a set of environmental parameters that are atypical for this regime. We discuss a hypothesis explaining the causes and mechanisms regulating the intensity and duration of Arctic circulation regimes, and speculate how changes in freshwater fluxes from the Arctic Ocean and Greenland impact environmental conditions and interrupt their decadal variability.

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De Swart, H. E. "Low-order spectral models of the atmospheric circulation: A survey." Acta Applicandae Mathematica 11, no. 1 (January 1988): 49–96. http://dx.doi.org/10.1007/bf00047114.

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Mukhin, Dmitry, Abdel Hannachi, Tobias Braun, and Norbert Marwan. "Revealing recurrent regimes of mid-latitude atmospheric variability using novel machine learning method." Chaos: An Interdisciplinary Journal of Nonlinear Science 32, no. 11 (November 2022): 113105. http://dx.doi.org/10.1063/5.0109889.

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The low-frequency variability of the extratropical atmosphere involves hemispheric-scale recurring, often persistent, states known as teleconnection patterns or regimes, which can have a profound impact on predictability on intra-seasonal and longer timescales. However, reliable data-driven identification and dynamical representation of such states are still challenging problems in modeling the dynamics of the atmosphere. We present a new method, which allows us both to detect recurring regimes of atmospheric variability and to obtain dynamical variables serving as an embedding for these regimes. The method combines two approaches from nonlinear data analysis: partitioning a network of recurrent states with studying its properties by the recurrence quantification analysis and the kernel principal component analysis. We apply the method to study teleconnection patterns in a quasi-geostrophical model of atmospheric circulation over the extratropical hemisphere as well as to reanalysis data of geopotential height anomalies in the mid-latitudes of the Northern Hemisphere atmosphere in the winter seasons from 1981 to the present. It is shown that the detected regimes as well as the obtained set of dynamical variables explain large-scale weather patterns, which are associated, in particular, with severe winters over Eurasia and North America. The method presented opens prospects for improving empirical modeling and long-term forecasting of large-scale atmospheric circulation regimes.

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Pierrehumbert, Raymond T., and Feng Ding. "Dynamics of atmospheres with a non-dilute condensible component." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 472, no. 2190 (June 2016): 20160107. http://dx.doi.org/10.1098/rspa.2016.0107.

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The diversity of characteristics for the host of recently discovered exoplanets opens up a great deal of fertile new territory for geophysical fluid dynamics, particularly when the fluid flow is coupled to novel thermodynamics, radiative transfer or chemistry. In this paper, we survey one of these new areas—the climate dynamics of atmospheres with a non-dilute condensible component, defined as the situation in which a condensible component of the atmosphere makes up a substantial fraction of the atmospheric mass within some layer. Non-dilute dynamics can occur for a wide range of condensibles, generically applying near both the inner and the outer edges of the conventional habitable zone and in connection with runaway greenhouse phenomena. It also applies in a wide variety of other planetary circumstances. We first present a number of analytical results developing some key features of non-dilute atmospheres, and then show how some of these features are manifest in simulations with a general circulation model adapted to handle non-dilute atmospheres. We find that non-dilute atmospheres have weak horizontal temperature gradients even for rapidly rotating planets, and that their circulations are largely barotropic. The relative humidity of the condensible component tends towards 100% as the atmosphere becomes more non-dilute, which has important implications for runaway greenhouse thresholds. Non-dilute atmospheres exhibit a number of interesting organized convection features, for which there is not yet any adequate theoretical understanding.

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Pan, Jiao-jiao, Qian Jiang, Ting-wei Ruan, and Hong Luo. "Regularity of Global Attractor for Atmospheric Circulation Equations with Humidity Effect." Acta Mathematicae Applicatae Sinica, English Series 35, no. 4 (September 2019): 820–29. http://dx.doi.org/10.1007/s10255-019-0855-1.

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Premakumari, Ramapura N., Chandrali Baishya, Pundikala Veeresha, and Lanre Akinyemi. "A Fractional Atmospheric Circulation System under the Influence of a Sliding Mode Controller." Symmetry 14, no. 12 (December 10, 2022): 2618. http://dx.doi.org/10.3390/sym14122618.

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The earth’s surface is heated by the large-scale movement of air known as atmospheric circulation, which works in conjunction with ocean circulation. More than 105 variables are involved in the complexity of the weather system. In this work, we analyze the dynamical behavior and chaos control of an atmospheric circulation model known as the Hadley circulation model, in the frame of Caputo and Caputo–Fabrizio fractional derivatives. The fundamental novelty of this paper is the application of the Caputo derivative with equal dimensionality to models that includes memory. A sliding mode controller (SMC) is developed to control chaos in this fractional-order atmospheric circulation system with uncertain dynamics. The proposed controller is applied to both commensurate and non-commensurate fractional-order systems. To demonstrate the intricacy of the models, we plot some graphs of various fractional orders with appropriate parameter values. We have observed the influence of thermal forcing on the dynamics of the system. The outcome of the analytical exercises is validated using numerical simulations.

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TSONIS, A. A. "THE IMPACT OF NONLINEAR DYNAMICS IN THE ATMOSPHERIC SCIENCES." International Journal of Bifurcation and Chaos 11, no. 04 (April 2001): 881–902. http://dx.doi.org/10.1142/s0218127401002663.

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In this review some of the achievements in atmospheric sciences that resulted from chaos theory and its implications are discussed. They include El Niño dynamics, physics and spatiotemporal dynamics of the general circulation, and ensemble forecasting.

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Teanby, Nicholas A., Patrick G. J. Irwin, Remco de Kok, and Conor A. Nixon. "Dynamical implications of seasonal and spatial variations in Titan's stratospheric composition." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 367, no. 1889 (November 20, 2008): 697–711. http://dx.doi.org/10.1098/rsta.2008.0164.

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Titan's diverse inventory of photochemically produced gases can be used as tracers to probe atmospheric circulation. Since the arrival of the Cassini–Huygens mission in July 2004 it has been possible to map the seasonal and spatial variations of these compounds in great detail. Here, we use 3.5 years of data measured by the Cassini Composite InfraRed Spectrometer instrument to determine spatial and seasonal composition trends, thus providing clues to underlying atmospheric motions. Titan's North Pole (currently in winter) displays enrichment of trace species, implying subsidence is occurring there. This is consistent with the descending branch of a single south-to-north stratospheric circulation cell and a polar vortex. Lack of enrichment in the south over most of the observed time period argues against the presence of any secondary circulation cell in the Southern Polar stratosphere. However, a residual cap of enriched gas was observed over the South Pole early in the mission, which has since completely dissipated. This cap was most probably due to residual build-up from southern winter. These observations provide new and important constraints for models of atmospheric photochemistry and circulation.

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Özelkan, Ertunga C., Ágnes Galambosi, Lucien Duckstein, and András Bárdossy. "A multi-objective fuzzy classification of large scale atmospheric circulation patterns for precipitation modeling." Applied Mathematics and Computation 91, no. 2-3 (May 1998): 127–42. http://dx.doi.org/10.1016/s0096-3003(97)10002-9.

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Thompson, Andrew F. "The atmospheric ocean: eddies and jets in the Antarctic Circumpolar Current." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 366, no. 1885 (September 25, 2008): 4529–41. http://dx.doi.org/10.1098/rsta.2008.0196.

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Although the Antarctic Circumpolar Current (ACC) is the longest and the strongest oceanic current on the Earth and is the primary means of inter-basin exchange, it remains one of the most poorly represented components of global climate models. Accurately describing the circulation of the ACC is made difficult owing to the prominent role that mesoscale eddies and jets, oceanic equivalents of atmospheric storms and storm tracks, have in setting the density structure and transport properties of the current. The successes and limitations of different representations of eddy processes in models of the ACC are considered, with particular attention given to how the circulation responds to changes in wind forcing. The dynamics of energetic eddies and topographically steered jets may both temper and enhance the sensitivity of different aspects of the ACC's circulation to changes in climate.

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Chetverushkin, B. N., I. V. Mingalev, E. A. Fedotova, K. G. Orlov, V. M. Chechetkin, and V. S. Mingalev. "Calculating the Natural Atmospheric Radiation Using the General Circulation Model of the Earth’s Lower and Middle Atmosphere." Mathematical Models and Computer Simulations 12, no. 5 (September 2020): 803–15. http://dx.doi.org/10.1134/s207004822005004x.

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Aplin, K. L., C. J. Scott, and S. L. Gray. "Atmospheric changes from solar eclipses." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 374, no. 2077 (September 28, 2016): 20150217. http://dx.doi.org/10.1098/rsta.2015.0217.

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This article reviews atmospheric changes associated with 44 solar eclipses, beginning with the first quantitative results available, from 1834 (earlier qualitative accounts also exist). Eclipse meteorology attracted relatively few publications until the total solar eclipse of 16 February 1980, with the 11 August 1999 eclipse producing the most papers. Eclipses passing over populated areas such as Europe, China and India now regularly attract scientific attention, whereas atmospheric measurements of eclipses at remote locations remain rare. Many measurements and models have been used to exploit the uniquely predictable solar forcing provided by an eclipse. In this paper, we compile the available publications and review a subset of them chosen on the basis of importance and novelty. Beyond the obvious reduction in incoming solar radiation, atmospheric cooling from eclipses can induce dynamical changes. Observations and meteorological modelling provide evidence for the generation of a local eclipse circulation that may be the origin of the ‘eclipse wind’. Gravity waves set up by the eclipse can, in principle, be detected as atmospheric pressure fluctuations, though theoretical predictions are limited, and many of the data are inconclusive. Eclipse events providing important early insights into the ionization of the upper atmosphere are also briefly reviewed. This article is part of the themed issue ‘Atmospheric effects of solar eclipses stimulated by the 2015 UK eclipse’.

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Franzke, Christian L. E. "Persistent regimes and extreme events of the North Atlantic atmospheric circulation." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 371, no. 1991 (May 28, 2013): 20110471. http://dx.doi.org/10.1098/rsta.2011.0471.

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Society is increasingly impacted by natural hazards which cause significant damage in economic and human terms. Many of these natural hazards are weather and climate related. Here, we show that North Atlantic atmospheric circulation regimes affect the propensity of extreme wind speeds in Europe. We also show evidence that extreme wind speeds are long-range dependent, follow a generalized Pareto distribution and are serially clustered. Serial clustering means that storms come in bunches and, hence, do not occur independently. We discuss the use of waiting time distributions for extreme event recurrence estimation in serially dependent time series.

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Hameed, Sultan, and Minghua Zhang. "Chaos and Predictability of Climate." International Journal of Bifurcation and Chaos 07, no. 12 (December 1997): 2881–90. http://dx.doi.org/10.1142/s0218127497001965.

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While day-to-day atmospheric fluctuations are not predictable after two weeks or so because of the chaotic nature of the atmospheric dynamics, there is evidence that certain aspects of the atmospheric circulation are predictable on time scales much longer than two weeks in the presence of a time dependent climate forcing. This paper illustrates distinctions between weather predictability and climate predictability by using a truncated atmospheric model in an explicitly chaotic parameter regime. An external forcing with time scale longer than the weather tends to modulate the statistical characteristics of the chaotic atmospheric variations to enhance the predictability of time-averaged climate states. Moreover, there exist climate variables which are more predictable than others.

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NICOLIS, C. "IRREVERSIBLE THERMODYNAMICS OF A SIMPLE ATMOSPHERIC FLOW MODEL." International Journal of Bifurcation and Chaos 12, no. 11 (November 2002): 2557–66. http://dx.doi.org/10.1142/s0218127402006035.

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The coexistence of different regimes in a class of atmospheric flow models is analyzed from the standpoint of irreversible thermodynamics. The entropy production, measuring the degree of dissipation within the system is evaluated across the bifurcation point. Some interesting trends are brought out, regarding the relative importance of dissipation in two qualitatively different circulation regimes referred to as zonal and blocked flows. It is shown that in the presence of stochastic disturbances entropy production exhibits critical behavior both in the vicinity of the bifurcation point and in parameter values where the two flow regimes are equally probable.

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Parkhomenko, V. P. "Organization of Numerical Experiments with an Atmospheric General Circulation Model and an Ocean Global Model." Computational Mathematics and Mathematical Physics 61, no. 10 (October 2021): 1661–71. http://dx.doi.org/10.1134/s0965542521100110.

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Jablonowski, Christiane, Robert C. Oehmke, and Quentin F. Stout. "Block-structured adaptive meshes and reduced grids for atmospheric general circulation models." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 367, no. 1907 (November 28, 2009): 4497–522. http://dx.doi.org/10.1098/rsta.2009.0150.

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Adaptive mesh refinement techniques offer a flexible framework for future variable-resolution climate and weather models since they can focus their computational mesh on certain geographical areas or atmospheric events. Adaptive meshes can also be used to coarsen a latitude–longitude grid in polar regions. This allows for the so-called reduced grid setups. A spherical, block-structured adaptive grid technique is applied to the Lin–Rood finite-volume dynamical core for weather and climate research. This hydrostatic dynamics package is based on a conservative and monotonic finite-volume discretization in flux form with vertically floating Lagrangian layers. The adaptive dynamical core is built upon a flexible latitude–longitude computational grid and tested in two- and three-dimensional model configurations. The discussion is focused on static mesh adaptations and reduced grids. The two-dimensional shallow water setup serves as an ideal testbed and allows the use of shallow water test cases like the advection of a cosine bell, moving vortices, a steady-state flow, the Rossby–Haurwitz wave or cross-polar flows. It is shown that reduced grid configurations are viable candidates for pure advection applications but should be used moderately in nonlinear simulations. In addition, static grid adaptations can be successfully used to resolve three-dimensional baroclinic waves in the storm-track region.

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Majda, Andrew J., Christian Franzke, and Boualem Khouider. "An applied mathematics perspective on stochastic modelling for climate." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 366, no. 1875 (April 29, 2008): 2427–53. http://dx.doi.org/10.1098/rsta.2008.0012.

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Systematic strategies from applied mathematics for stochastic modelling in climate are reviewed here. One of the topics discussed is the stochastic modelling of mid-latitude low-frequency variability through a few teleconnection patterns, including the central role and physical mechanisms responsible for multiplicative noise. A new low-dimensional stochastic model is developed here, which mimics key features of atmospheric general circulation models, to test the fidelity of stochastic mode reduction procedures. The second topic discussed here is the systematic design of stochastic lattice models to capture irregular and highly intermittent features that are not resolved by a deterministic parametrization. A recent applied mathematics design principle for stochastic column modelling with intermittency is illustrated in an idealized setting for deep tropical convection; the practical effect of this stochastic model in both slowing down convectively coupled waves and increasing their fluctuations is presented here.

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Tomita, Hirofumi, Koji Goto, and Masaki Satoh. "A New Approach to Atmospheric General Circulation Model: Global Cloud Resolving Model NICAM and its Computational Performance." SIAM Journal on Scientific Computing 30, no. 6 (January 2008): 2755–76. http://dx.doi.org/10.1137/070692273.

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Gritsun, A. "Statistical characteristics, circulation regimes and unstable periodic orbits of a barotropic atmospheric model." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 371, no. 1991 (May 28, 2013): 20120336. http://dx.doi.org/10.1098/rsta.2012.0336.

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The theory of chaotic dynamical systems gives many tools that can be used in climate studies. The widely used ones are the Lyapunov exponents, the Kolmogorov entropy and the attractor dimension characterizing global quantities of a system. Another potentially useful tool from dynamical system theory arises from the fact that the local analysis of a system probability distribution function (PDF) can be accomplished by using a procedure that involves an expansion in terms of unstable periodic orbits (UPOs). The system measure (or its statistical characteristics) is approximated as a weighted sum over the orbits. The weights are inversely proportional to the orbit instability characteristics so that the least unstable orbits make larger contributions to the PDF. Consequently, one can expect some relationship between the least unstable orbits and the local maxima of the system PDF. As a result, the most probable system trajectories (or ‘circulation regimes’ in some sense) may be explained in terms of orbits. For the special classes of chaotic dynamical systems, there is a strict theory guaranteeing the accuracy of this approach. However, a typical atmospheric model may not qualify for these theorems. In our study, we will try to apply the idea of UPO expansion to the simple atmospheric system based on the barotropic vorticity equation of the sphere. We will check how well orbits approximate the system attractor, its statistical characteristics and PDF. The connection of the most probable states of the system with the least unstable periodic orbits will also be analysed.

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Fomin, V. V., I. I. Panasenkova, A. V. Gusev, A. V. Chaplygin, and N. A. Diansky. "Operational forecasting system for Arctic Ocean using the Russian marine circulation model INMOM-Arctic." Arctic: Ecology and Economy 11, no. 2 (June 2021): 205–18. http://dx.doi.org/10.25283/2223-4594-2021-2-205-218.

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A regional σ-model INMOM-Arctic has been prepared on the basis of the Russian ocean general circulation model INMOM (Institute of Numerical Mathematics Ocean Model) to reproduce the current state and short-term forecast of the Arctic Ocean (AO) hydrothermodynamics. The model is implemented in a rotated spherical coordinate system with the poles located at 60°E and 120° W on the geographic equator, which makes it possible to use a quasi-uniform resolution of ~ 3,7 km in the Arctic Basin. Data on temperature, salinity, horizontal velocity components and sea level taken from the CMEMS ocean products are used at the AO open boundaries. To take into account the tidal effect in the INMOM-Arctic model at open boundaries, the time series of the tidal sea level is set based on the data of the TPXO 9 atlas (TOPEX/Poseidon Global Tidal Model) with a spatial resolution of 1/30°. To calculate the atmospheric impact, the researches use the atmospheric circulation data from the Era 5 global reanalysis with a spatial resolution of 0,25×0,25° and with a temporal resolution of 1 hour.

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Freire, Joana G., Cristian Bonatto, Carlos C. DaCamara, and Jason A. C. Gallas. "Multistability, phase diagrams, and intransitivity in the Lorenz-84 low-order atmospheric circulation model." Chaos: An Interdisciplinary Journal of Nonlinear Science 18, no. 3 (September 2008): 033121. http://dx.doi.org/10.1063/1.2953589.

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Sapriza Azuri, Gonzalo, Jorge Jódar, Jesús Carrera, and Hoshin V. Gupta. "Stochastic Simulation of Nonstationary Rainfall Fields, Accounting for Seasonality and Atmospheric Circulation Pattern Evolution." Mathematical Geosciences 45, no. 5 (July 2013): 621–45. http://dx.doi.org/10.1007/s11004-013-9467-0.

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Dunkley Jones, T., A. Ridgwell, D. J. Lunt, M. A. Maslin, D. N. Schmidt, and P. J. Valdes. "A Palaeogene perspective on climate sensitivity and methane hydrate instability." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 368, no. 1919 (May 28, 2010): 2395–415. http://dx.doi.org/10.1098/rsta.2010.0053.

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The Palaeocene–Eocene thermal maximum (PETM), a rapid global warming event and carbon-cycle perturbation of the early Palaeogene, provides a unique test of climate and carbon-cycle models as well as our understanding of sedimentary methane hydrate stability, albeit under conditions very different from the modern. The principal expression of the PETM in the geological record is a large and rapid negative excursion in the carbon isotopic composition of carbonates and organic matter from both marine and terrestrial environments. Palaeotemperature proxy data from across the PETM indicate a coincident increase in global surface temperatures of approximately 5–6°C. Reliable estimates of atmospheric CO 2 changes and global warming through past transient climate events can provide an important test of the climate sensitivities reproduced by state-of-the-art atmosphere–ocean general circulation models. Here, we synthesize the available carbon-cycle model estimates of the magnitude of the carbon input to the ocean–atmosphere–biosphere system, and the consequent atmospheric p CO 2 perturbation, through the PETM. We also review the theoretical mass balance arguments and available sedimentary evidence for the role of massive methane hydrate dissociation in this event. The plausible range of carbon mass input, approximately 4000–7000 PgC, strongly suggests a major alternative source of carbon in addition to any contribution from methane hydrates. We find that the potential range of PETM atmospheric p CO 2 increase, combined with proxy estimates of the PETM temperature anomaly, does not necessarily imply climate sensitivities beyond the range of state-of-the-art climate models.

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LINK, RAINER, and HORST-JOACHIM LÜDECKE. "A NEW BASIC ONE-DIMENSIONAL ONE-LAYER MODEL OBTAINS EXCELLENT AGREEMENT WITH THE OBSERVED EARTH TEMPERATURE." International Journal of Modern Physics C 22, no. 05 (May 2011): 449–55. http://dx.doi.org/10.1142/s0129183111016361.

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The Earth radiation and energy budget is calculated by a manifold of rather complex Global Circulation Models. Their outcome mostly cannot identify integral radiation or energy budget relations. Therefore it is reasonable to look at more basic models to identify the main aspects of the model results. The simplest one of all of those is a one-dimensional one-layer model. However, most of these models — two are discussed here — suffer the drawback that they do not include essential contributions and relations between the atmospheric layer and the Earth. The one-dimensional one-layer model presented here integrates sensible and latent heat, the absorption of solar radiation and the direct emission of the long wave radiation to space in addition to the standard correlations. For the atmospheric layer two different long wave fluxes are included, top of atmosphere to space and bulk emission to Earth. The reflections of long wave radiation are taken into account. It is shown that this basic model is in excellent agreement with the observed integrated global energy budget.

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Sperberg, Ulrich. "Eduard Heis, an early pioneer in meteor research." History of Geo- and Space Sciences 12, no. 2 (September 23, 2021): 163–70. http://dx.doi.org/10.5194/hgss-12-163-2021.

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Abstract. At the beginning of the 19th century, meteor observations were not well established. One of its pioneers, who observed meteors on a regular basis, was Eduard Heis in Münster, Germany. We summarise the life of this scientist. Besides his main task of teaching mathematics in Aachen and Münster, he observed atmospheric phenomena and variable stars with exceptional perseverance. He was an editor of Wochenschrift für Astronomie and contributed to the circulation of astronomical reports and knowledge. We focus on his contributions to meteor astronomy, in which he predated the work of Schiaparelli by 30 years.

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Shepherd, Theodore G. "Storyline approach to the construction of regional climate change information." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 475, no. 2225 (May 2019): 20190013. http://dx.doi.org/10.1098/rspa.2019.0013.

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Climate science seeks to make statements of confidence about what has happened, and what will happen (conditional on scenario). The approach is effective for the global, thermodynamic aspects of climate change, but is ineffective when it comes to aspects of climate change related to atmospheric circulation, which are highly uncertain. Yet, atmospheric circulation strongly mediates climate impacts at the regional scale. In this way, the confidence framework, which focuses on avoiding type 1 errors (false alarms), raises the prospect of committing type 2 errors (missed warnings). This has ethical implications. At the regional scale, however, where information on climate change has to be combined with many other factors affecting vulnerability and exposure—most of which are highly uncertain—the societally relevant question is not ‘What will happen?’ but rather ‘What is the impact of particular actions under an uncertain regional climate change?’ This reframing of the question can cut the Gordian knot of regional climate change information, provided one distinguishes between epistemic and aleatoric uncertainties—something that is generally not done in climate projections. It is argued that the storyline approach to climate change—the identification of physically self-consistent, plausible pathways—has the potential to accomplish precisely this.

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Tokano, Tetsuya. "The dynamics of Titan's troposphere." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 367, no. 1889 (November 19, 2008): 633–48. http://dx.doi.org/10.1098/rsta.2008.0163.

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While the Voyager mission could essentially not reveal the dynamics of Titan's troposphere, useful information was obtained by the Cassini spacecraft and, particularly, by the Huygens probe that landed on Titan's surface; this information can be interpreted by means of numerical models of atmospheric circulation. The meridional circulation is likely to consist of a large Hadley circulation asymmetric about the equator, but is susceptible to disruption by turbulence in clouds. The zonal wind in the troposphere is comparable to or even weaker than that in the terrestrial troposphere and contains zones of easterlies, much in contrast to the super-rotating stratosphere. Unique to Titan is the transition from a geostrophic to cyclostrophic wind balance in the upper troposphere. While Earth-like storm systems associated with baroclinic instability are absent, Saturn's gravitational tide introduces a planetary wave of wavenumber 2 and a periodical variation in the wind direction in the troposphere. Unlike on Earth, the wind over the equatorial surface is westerly. The seasonal reversal in the Hadley circulation sense and zonal wind direction is predicted to have a substantial influence on the formation of dunes as well as variation of Titan's rotation rate and length of day.

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Vargin, Pavel N., Sergey V. Kostrykin, Evgeni M. Volodin, Alexander I. Pogoreltsev, and Ke Wei. "Arctic Stratosphere Circulation Changes in the 21st Century in Simulations of INM CM5." Atmosphere 13, no. 1 (December 24, 2021): 25. http://dx.doi.org/10.3390/atmos13010025.

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Simulations of Institute of Numerical Mathematics (INM) coupled climate model 5th version for the period from 2015 to 2100 under moderate (SSP2-4.5) and severe (SSP5-8.5) scenarios of greenhouse gases growth are analyzed to investigate changes of Arctic polar stratospheric vortex, planetary wave propagation, Sudden Stratospheric Warming frequency, Final Warming dates, and meridional circulation. Strengthening of wave activity propagation and a stationary planetary wave number 1 in the middle and upper stratosphere, acceleration of meridional circulation, an increase of winter mean polar stratospheric volume (Vpsc) and strengthening of Arctic stratosphere interannual variability after the middle of 21st century, especially under a severe scenario, were revealed. March monthly values of Vpsc in some winters could be about two times more than observed ones in the Arctic stratosphere in the spring of 2011 and 2020, which in turn could lead to large ozone layer destruction. Composite analysis shows that “warm” winters with the least winter mean Vpsc values are characterized by strengthening of wave activity propagation from the troposphere into the stratosphere in December but weaker propagation in January–February in comparison with winters having the largest Vpsc values.

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Ehstand, Noémie, Reik V. Donner, Cristóbal López, and Emilio Hernández-García. "Characteristic signatures of Northern Hemisphere blocking events in a Lagrangian flow network representation of the atmospheric circulation." Chaos: An Interdisciplinary Journal of Nonlinear Science 31, no. 9 (September 2021): 093128. http://dx.doi.org/10.1063/5.0057409.

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Bonatto, Cristian, and Jason Alfredo Carlson Gallas. "Accumulation boundaries: codimension-two accumulation of accumulations in phase diagrams of semiconductor lasers, electric circuits, atmospheric and chemical oscillators." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 366, no. 1865 (August 13, 2007): 505–17. http://dx.doi.org/10.1098/rsta.2007.2107.

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We report high-resolution phase diagrams for several familiar dynamical systems described by sets of ordinary differential equations: semiconductor lasers; electric circuits; Lorenz-84 low-order atmospheric circulation model; and Rössler and chemical oscillators. All these systems contain chaotic phases with highly complicated and interesting accumulation boundaries , curves where networks of stable islands of regular oscillations with ever-increasing periodicities accumulate systematically. The experimental exploration of such codimension-two boundaries characterized by the presence of infinite accumulation of accumulations is feasible with existing technology for some of these systems.

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Tsoy, Alexandr, Alexandr Granovskiy, Diana Tsoy, and Dmitriy Koretskiy. "Cooling capacity of experimental system with natural refrigerant circulation and condenser radiative cooling." Eastern-European Journal of Enterprise Technologies 2, no. 8 (116) (April 30, 2022): 45–53. http://dx.doi.org/10.15587/1729-4061.2022.253651.

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The surface of the Earth is a source of radiation of thermal energy, which, passing through the atmosphere, is partially absorbed while the bulk of the energy is released into the surrounding outer space. A cooling technique based on this physical phenomenon is known as radiative cooling (RC). It is possible to reduce the consumption of electricity for cooling, as well as to reduce capital costs, by integrating the unit with radiative cooling directly into the circulation circuit of the refrigerant of the refrigeration machine. An experimental refrigeration system has been designed, in which in the cold periods of the year the removal of heat from the cooled object is carried out due to the mode of natural circulation of the refrigerant from the evaporator to the heat exchanger, cooled by radiative cooling. A refrigeration system with natural circulation and radiative cooling of the refrigerant R134a was experimentally studied during the autumn period in Almaty. The experimental study established that the chamber is cooled with the help of the examined system while the temperature in the cooled volume is maintained by 5...7 K above ambient air temperature at night. The dependence of the air temperature in the refrigerating chamber on the temperature of the atmospheric air has been determined. A procedure for assessing the cooling capacity of the system has been devised. The study reported here demonstrated the possibility of using radiative cooling to remove heat under the mode of natural circulation of the refrigerant. The refrigeration system reduces energy consumption in the cold seasons by diverting heat to the environment without the compressor operating

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Weisheimer, Antje, Susanna Corti, Tim Palmer, and Frederic Vitart. "Addressing model error through atmospheric stochastic physical parametrizations: impact on the coupled ECMWF seasonal forecasting system." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 372, no. 2018 (June 28, 2014): 20130290. http://dx.doi.org/10.1098/rsta.2013.0290.

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The finite resolution of general circulation models of the coupled atmosphere–ocean system and the effects of sub-grid-scale variability present a major source of uncertainty in model simulations on all time scales. The European Centre for Medium-Range Weather Forecasts has been at the forefront of developing new approaches to account for these uncertainties. In particular, the stochastically perturbed physical tendency scheme and the stochastically perturbed backscatter algorithm for the atmosphere are now used routinely for global numerical weather prediction. The European Centre also performs long-range predictions of the coupled atmosphere–ocean climate system in operational forecast mode, and the latest seasonal forecasting system—System 4—has the stochastically perturbed tendency and backscatter schemes implemented in a similar way to that for the medium-range weather forecasts. Here, we present results of the impact of these schemes in System 4 by contrasting the operational performance on seasonal time scales during the retrospective forecast period 1981–2010 with comparable simulations that do not account for the representation of model uncertainty. We find that the stochastic tendency perturbation schemes helped to reduce excessively strong convective activity especially over the Maritime Continent and the tropical Western Pacific, leading to reduced biases of the outgoing longwave radiation (OLR), cloud cover, precipitation and near-surface winds. Positive impact was also found for the statistics of the Madden–Julian oscillation (MJO), showing an increase in the frequencies and amplitudes of MJO events. Further, the errors of El Niño southern oscillation forecasts become smaller, whereas increases in ensemble spread lead to a better calibrated system if the stochastic tendency is activated. The backscatter scheme has overall neutral impact. Finally, evidence for noise-activated regime transitions has been found in a cluster analysis of mid-latitude circulation regimes over the Pacific–North America region.

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Serreze, Mark C., and Julienne Stroeve. "Arctic sea ice trends, variability and implications for seasonal ice forecasting." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 373, no. 2045 (July 13, 2015): 20140159. http://dx.doi.org/10.1098/rsta.2014.0159.

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September Arctic sea ice extent over the period of satellite observations has a strong downward trend, accompanied by pronounced interannual variability with a detrended 1 year lag autocorrelation of essentially zero. We argue that through a combination of thinning and associated processes related to a warming climate (a stronger albedo feedback, a longer melt season, the lack of especially cold winters) the downward trend itself is steepening. The lack of autocorrelation manifests both the inherent large variability in summer atmospheric circulation patterns and that oceanic heat loss in winter acts as a negative (stabilizing) feedback, albeit insufficient to counter the steepening trend. These findings have implications for seasonal ice forecasting. In particular, while advances in observing sea ice thickness and assimilating thickness into coupled forecast systems have improved forecast skill, there remains an inherent limit to predictability owing to the largely chaotic nature of atmospheric variability.

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Haywood, Alan M., Harry J. Dowsett, Paul J. Valdes, Daniel J. Lunt, Jane E. Francis, and Bruce W. Sellwood. "Introduction. Pliocene climate, processes and problems." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 367, no. 1886 (October 13, 2008): 3–17. http://dx.doi.org/10.1098/rsta.2008.0205.

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Climate predictions produced by numerical climate models, often referred to as general circulation models (GCMs), suggest that by the end of the twenty-first century global mean annual surface air temperatures will increase by 1.1–6.4°C. Trace gas records from ice cores indicate that atmospheric concentrations of CO 2 are already higher than at any time during the last 650 000 years. In the next 50 years, atmospheric CO 2 concentrations are expected to reach a level not encountered since an epoch of time known as the Pliocene. Uniformitarianism is a key principle of geological science, but can the past also be a guide to the future? To what extent does an examination of the Pliocene geological record enable us to successfully understand and interpret this guide? How reliable are the ‘retrodictions’ of Pliocene climates produced by GCMs and what does this tell us about the accuracy of model predictions for the future? These questions provide the scientific rationale for this Theme Issue.

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Do Hoai, Nam, Keiko Udo, and Akira Mano. "Downscaling Global Weather Forecast Outputs Using ANN for Flood Prediction." Journal of Applied Mathematics 2011 (2011): 1–14. http://dx.doi.org/10.1155/2011/246286.

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Downscaling global weather prediction model outputs to individual locations or local scales is a common practice for operational weather forecast in order to correct the model outputs at subgrid scales. This paper presents an empirical-statistical downscaling method for precipitation prediction which uses a feed-forward multilayer perceptron (MLP) neural network. The MLP architecture was optimized by considering physical bases that determine the circulation of atmospheric variables. Downscaled precipitation was then used as inputs to the super tank model (runoff model) for flood prediction. The case study was conducted for the Thu Bon River Basin, located in Central Vietnam. Study results showed that the precipitation predicted by MLP outperformed that directly obtained from model outputs or downscaled using multiple linear regression. Consequently, flood forecast based on the downscaled precipitation was very encouraging. It has demonstrated as a robust technology, simple to implement, reliable, and universal application for flood prediction through the combination of downscaling model and super tank model.

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Chen, Zhi-Min. "Low-Index Equilibrium and Multiple Period-Doubling Cascades to Chaos of Atmospheric Flow in Beta-Plane Channel." International Journal of Bifurcation and Chaos 26, no. 08 (July 2016): 1630020. http://dx.doi.org/10.1142/s0218127416300202.

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The nonlinear dynamical behavior of an atmospheric circulation in a beta-plane channel is examined on a five-spectral mode model, truncated from the Charney and DeVore quasi-geostrophic equation. Bifurcation and chaos are observed when subjected to a topographic driving disturbance and a thermally driving zonal source. An equilibrium state undergoes supercritical Hopf bifurcation and becomes a stable periodic state with respect to the magnitude of the thermally driving source, whereas the periodic state undergoes a subcritical Hopf bifurcation and transforms into a low-index equilibrium state with respect to the increasing topographic driving disturbance. The stable periodic state further develops into a pair of stable periodic states when increasing the thermally driving source. The first one with the period of 4.3 days exhibits an oscillation of strong and weak zonal flow patterns, whereas the second one with the period of 6.8 days demonstrates a fluctuation amongst weak zonal disturbance flow patterns. Moreover, the two periodic states transform respectively into chaos through separate period-doubling cascades with the further development of the thermally driving source.

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Byshev, V. I., M. V. Anisimov, A. V. Gusev, V. M. Gruzinov, and A. N. Sidorova. "ON THE MULTI-DECADAL OSCILLATION OF THE HEAT CONTENT OF THE WORLD OCEAN." Journal of Oceanological Research 48, no. 3 (October 30, 2020): 76–95. http://dx.doi.org/10.29006/1564-2291.jor-2020.48(3).5.

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Multi-decade rhythmicity is one of the most important features of the dynamics of the modern climate. The rhythm of 1940–1999 was a two-phase structure in which the initial phase (1940–1974) was essentially continental, and the final phase (1975–1999) was relatively wet. The transition of the climate from the continental phase to the humid one in the mid-70s of the twentieth century was “sudden” and recognized as a climate shift. A certain globality and quasi-synchronicity of multi-decade climate changes is realized with the participation of planetary thermodynamic structures both in the ocean and in the atmosphere of two the most important components of the climate system. The presence of a Global atmospheric oscillation was discovered and studied in detail. This paper offers the first attempt to consider the content and features of the planetary multi-decadal oscillation of the heat content of the World Ocean. The analysis of ocean oscillation is based on the results of numerical simulation of the World Ocean water circulation in the period from 1948 to 2007 using the model of the Marchuk Institute of Numerical Mathematics of Russian Academy of Sciences. The differences in the average water temperature fields in the upper 1200-meter layer, calculated for two opposite phases of the oscillation, revealed the main features of its structure.

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MOUS, SIPKO L. J., and JOHAN GRASMAN. "TWO METHODS FOR ASSESSING THE SIZE OF EXTERNAL PERTURBATIONS IN CHAOTIC PROCESSES." Mathematical Models and Methods in Applied Sciences 03, no. 04 (August 1993): 577–93. http://dx.doi.org/10.1142/s0218202593000291.

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This paper deals with the assessment of an external perturbation in nonlinear chaotic dynamical processes using either a modified sentinel function or an extended Kalman filter treatment. We consider processes that can be modeled by a system of nonlinear ordinary differential equations. The sentinel function is used to detect an external perturbation, that is not included in the model of the process. In cases where the time dependency of the external perturbation is known but the size of the perturbation is unknown, the sentinel function is also used to estimate the size of this perturbation. We have compared this approach to estimate the size of a perturbation with an extended Kalman filter treatment and as an example to illustrate these two approaches we have analyzed a lower order spectral model of the atmospheric circulation with a perturbed equator-pole temperature gradient.

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Kennedy, A. T., A. Farnsworth, D. J. Lunt, C. H. Lear, and P. J. Markwick. "Atmospheric and oceanic impacts of Antarctic glaciation across the Eocene–Oligocene transition." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 373, no. 2054 (November 13, 2015): 20140419. http://dx.doi.org/10.1098/rsta.2014.0419.

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The glaciation of Antarctica at the Eocene–Oligocene transition (approx. 34 million years ago) was a major shift in the Earth’s climate system, but the mechanisms that caused the glaciation, and its effects, remain highly debated. A number of recent studies have used coupled atmosphere–ocean climate models to assess the climatic effects of Antarctic glacial inception, with often contrasting results. Here, using the HadCM3L model, we show that the global atmosphere and ocean response to growth of the Antarctic ice sheet is sensitive to subtle variations in palaeogeography, using two reconstructions representing Eocene and Oligocene geological stages. The earlier stage (Eocene; Priabonian), which has a relatively constricted Tasman Seaway, shows a major increase in sea surface temperature over the Pacific sector of the Southern Ocean in response to the ice sheet. This response does not occur for the later stage (Oligocene; Rupelian), which has a more open Tasman Seaway. This difference in temperature response is attributed to reorganization of ocean currents between the stages. Following ice sheet expansion in the earlier stage, the large Ross Sea gyre circulation decreases in size. Stronger zonal flow through the Tasman Seaway allows salinities to increase in the Ross Sea, deep-water formation initiates and multiple feedbacks then occur amplifying the temperature response. This is potentially a model-dependent result, but it highlights the sensitive nature of model simulations to subtle variations in palaeogeography, and highlights the need for coupled ice sheet–climate simulations to properly represent and investigate feedback processes acting on these time scales.

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Lenton, T. M., V. N. Livina, V. Dakos, E. H. van Nes, and M. Scheffer. "Early warning of climate tipping points from critical slowing down: comparing methods to improve robustness." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 370, no. 1962 (March 13, 2012): 1185–204. http://dx.doi.org/10.1098/rsta.2011.0304.

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We address whether robust early warning signals can, in principle, be provided before a climate tipping point is reached, focusing on methods that seek to detect critical slowing down as a precursor of bifurcation. As a test bed, six previously analysed datasets are reconsidered, three palaeoclimate records approaching abrupt transitions at the end of the last ice age and three models of varying complexity forced through a collapse of the Atlantic thermohaline circulation. Approaches based on examining the lag-1 autocorrelation function or on detrended fluctuation analysis are applied together and compared. The effects of aggregating the data, detrending method, sliding window length and filtering bandwidth are examined. Robust indicators of critical slowing down are found prior to the abrupt warming event at the end of the Younger Dryas, but the indicators are less clear prior to the Bølling-Allerød warming, or glacial termination in Antarctica. Early warnings of thermohaline circulation collapse can be masked by inter-annual variability driven by atmospheric dynamics. However, rapidly decaying modes can be successfully filtered out by using a long bandwidth or by aggregating data. The two methods have complementary strengths and weaknesses and we recommend applying them together to improve the robustness of early warnings.

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Meijers, A. J. S. "The Southern Ocean in the Coupled Model Intercomparison Project phase 5." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 372, no. 2019 (July 13, 2014): 20130296. http://dx.doi.org/10.1098/rsta.2013.0296.

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The Southern Ocean is an important part of the global climate system, but its complex coupled nature makes both its present state and its response to projected future climate forcing difficult to model. Clear trends in wind, sea-ice extent and ocean properties emerged from multi-model intercomparison in the Coupled Model Intercomparison Project phase 3 (CMIP3). Here, we review recent analyses of the historical and projected wind, sea ice, circulation and bulk properties of the Southern Ocean in the updated Coupled Model Intercomparison Project phase 5 (CMIP5) ensemble. Improvements to the models include higher resolutions, more complex and better-tuned parametrizations of ocean mixing, and improved biogeochemical cycles and atmospheric chemistry. CMIP5 largely reproduces the findings of CMIP3, but with smaller inter-model spreads and biases. By the end of the twenty-first century, mid-latitude wind stresses increase and shift polewards. All water masses warm, and intermediate waters freshen, while bottom waters increase in salinity. Surface mixed layers shallow, warm and freshen, whereas sea ice decreases. The upper overturning circulation intensifies, whereas bottom water formation is reduced. Significant disagreement exists between models for the response of the Antarctic Circumpolar Current strength, for reasons that are as yet unclear.

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Francis, Jennifer, and Natasa Skific. "Evidence linking rapid Arctic warming to mid-latitude weather patterns." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 373, no. 2045 (July 13, 2015): 20140170. http://dx.doi.org/10.1098/rsta.2014.0170.

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The effects of rapid Arctic warming and ice loss on weather patterns in the Northern Hemisphere is a topic of active research, lively scientific debate and high societal impact. The emergence of Arctic amplification—the enhanced sensitivity of high-latitude temperature to global warming—in only the last 10–20 years presents a challenge to identifying statistically robust atmospheric responses using observations. Several recent studies have proposed and demonstrated new mechanisms by which the changing Arctic may be affecting weather patterns in mid-latitudes, and these linkages differ fundamentally from tropics/jet-stream interactions through the transfer of wave energy. In this study, new metrics and evidence are presented that suggest disproportionate Arctic warming—and resulting weakening of the poleward temperature gradient—is causing the Northern Hemisphere circulation to assume a more meridional character (i.e. wavier), although not uniformly in space or by season, and that highly amplified jet-stream patterns are occurring more frequently. Further analysis based on self-organizing maps supports this finding. These changes in circulation are expected to lead to persistent weather patterns that are known to cause extreme weather events. As emissions of greenhouse gases continue unabated, therefore, the continued amplification of Arctic warming should favour an increased occurrence of extreme events caused by prolonged weather conditions.

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Lopez-Restrepo, Santiago, Elias D. Nino-Ruiz, Luis G. Guzman-Reyes, Andres Yarce, O. L. Quintero, Nicolas Pinel, Arjo Segers, and A. W. Heemink. "An efficient ensemble Kalman Filter implementation via shrinkage covariance matrix estimation: exploiting prior knowledge." Computational Geosciences 25, no. 3 (February 11, 2021): 985–1003. http://dx.doi.org/10.1007/s10596-021-10035-4.

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AbstractIn this paper, we propose an efficient and practical implementation of the ensemble Kalman filter via shrinkage covariance matrix estimation. Our filter implementation combines information brought by an ensemble of model realizations, and that based on our prior knowledge about the dynamical system of interest. We perform the combination of both sources of information via optimal shrinkage factors. The method exploits the rank-deficiency of ensemble covariance matrices to provide an efficient and practical implementation of the analysis step in EnKF based formulations. Localization and inflation aspects are discussed, as well. Experimental tests are performed to assess the accuracy of our proposed filter implementation by employing an Advection Diffusion Model and an Atmospheric General Circulation Model. The experimental results reveal that the use of our proposed filter implementation can mitigate the impact of sampling noise, and even more, it can avoid the impact of spurious correlations during assimilation steps.

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Brayshaw, David James, Brian Hoskins, and Emily Black. "Some physical drivers of changes in the winter storm tracks over the North Atlantic and Mediterranean during the Holocene." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 368, no. 1931 (November 28, 2010): 5185–223. http://dx.doi.org/10.1098/rsta.2010.0180.

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The winter climate of Europe and the Mediterranean is dominated by the weather systems of the mid-latitude storm tracks. The behaviour of the storm tracks is highly variable, particularly in the eastern North Atlantic, and has a profound impact on the hydroclimate of the Mediterranean region. A deeper understanding of the storm tracks and the factors that drive them is therefore crucial for interpreting past changes in Mediterranean climate and the civilizations it has supported over the last 12 000 years (broadly the Holocene period). This paper presents a discussion of how changes in climate forcing (e.g. orbital variations, greenhouse gases, ice sheet cover) may have impacted on the ‘basic ingredients’ controlling the mid-latitude storm tracks over the North Atlantic and the Mediterranean on intermillennial time scales. Idealized simulations using the HadAM3 atmospheric general circulation model (GCM) are used to explore the basic processes, while a series of timeslice simulations from a similar atmospheric GCM coupled to a thermodynamic slab ocean (HadSM3) are examined to identify the impact these drivers have on the storm track during the Holocene. The results suggest that the North Atlantic storm track has moved northward and strengthened with time since the Early to Mid-Holocene. In contrast, the Mediterranean storm track may have weakened over the same period. It is, however, emphasized that much remains still to be understood about the evolution of the North Atlantic and Mediterranean storm tracks during the Holocene period.

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Sagoo, Navjit, Paul Valdes, Rachel Flecker, and Lauren J. Gregoire. "The Early Eocene equable climate problem: can perturbations of climate model parameters identify possible solutions?" Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 371, no. 2001 (October 28, 2013): 20130123. http://dx.doi.org/10.1098/rsta.2013.0123.

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Geological data for the Early Eocene (56–47.8 Ma) indicate extensive global warming, with very warm temperatures at both poles. However, despite numerous attempts to simulate this warmth, there are remarkable data–model differences in the prediction of these polar surface temperatures, resulting in the so-called ‘equable climate problem’. In this paper, for the first time an ensemble with a perturbed climate-sensitive model parameters approach has been applied to modelling the Early Eocene climate. We performed more than 100 simulations with perturbed physics parameters, and identified two simulations that have an optimal fit with the proxy data. We have simulated the warmth of the Early Eocene at 560 ppmv CO 2 , which is a much lower CO 2 level than many other models. We investigate the changes in atmospheric circulation, cloud properties and ocean circulation that are common to these simulations and how they differ from the remaining simulations in order to understand what mechanisms contribute to the polar warming. The parameter set from one of the optimal Early Eocene simulations also produces a favourable fit for the last glacial maximum boundary climate and outperforms the control parameter set for the present day. Although this does not ‘prove’ that this model is correct, it is very encouraging that there is a parameter set that creates a climate model able to simulate well very different palaeoclimates and the present-day climate. Interestingly, to achieve the great warmth of the Early Eocene this version of the model does not have a strong future climate change Charney climate sensitivity. It produces a Charney climate sensitivity of 2.7 ° C, whereas the mean value of the 18 models in the IPCC Fourth Assessment Report (AR4) is 3.26 ° C±0.69 ° C. Thus, this value is within the range and below the mean of the models included in the AR4.

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Rhein, Monika, Reiner Steinfeldt, Dagmar Kieke, Ilaria Stendardo, and Igor Yashayaev. "Ventilation variability of Labrador Sea Water and its impact on oxygen and anthropogenic carbon: a review." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 375, no. 2102 (August 7, 2017): 20160321. http://dx.doi.org/10.1098/rsta.2016.0321.

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Ventilation of Labrador Sea Water (LSW) receives ample attention because of its potential relation to the strength of the Atlantic Meridional Overturning Circulation (AMOC). Here, we provide an overview of the changes of LSW from observations in the Labrador Sea and from the southern boundary of the subpolar gyre at 47° N. A strong winter-time atmospheric cooling over the Labrador Sea led to intense and deep convection, producing a thick and dense LSW layer as, for instance, in the early to mid-1990s. The weaker convection in the following years mostly ventilated less dense LSW vintages and also reduced the supply of oxygen. As a further consequence, the rate of uptake of anthropogenic carbon by LSW decreased between the two time periods 1996–1999 and 2007–2010 in the western subpolar North Atlantic. In the eastern basins, the rate of increase in anthropogenic carbon became greater due to the delayed advection of LSW that was ventilated in previous years. Starting in winter 2013/2014 and prevailing at least into winter 2015/2016, production of denser and more voluminous LSW resumed. Increasing oxygen signals have already been found in the western boundary current at 47° N. On decadal and shorter time scales, anomalous cold atmospheric conditions over the Labrador Sea lead to an intensification of convection. On multi-decadal time scales, the ‘cold blob’ in the subpolar North Atlantic projected by climate models in the next 100 years is linked to a weaker AMOC and weaker convection (and thus deoxygenation) in the Labrador Sea. This article is part of the themed issue ‘Ocean ventilation and deoxygenation in a warming world’.

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Self, S. "The effects and consequences of very large explosive volcanic eruptions." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 364, no. 1845 (June 28, 2006): 2073–97. http://dx.doi.org/10.1098/rsta.2006.1814.

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Every now and again Earth experiences tremendous explosive volcanic eruptions, considerably bigger than the largest witnessed in historic times. Those yielding more than 450 km 3 of magma have been called super-eruptions. The record of such eruptions is incomplete; the most recent known example occurred 26 000 years ago. It is more likely that the Earth will next experience a super-eruption than an impact from a large meteorite greater than 1 km in diameter. Depending on where the volcano is located, the effects will be felt globally or at least by a whole hemisphere. Large areas will be devastated by pyroclastic flow deposits, and the more widely dispersed ash falls will be laid down over continent-sized areas. The most widespread effects will be derived from volcanic gases, sulphur gases being particularly important. This gas is converted into sulphuric acid aerosols in the stratosphere and layers of aerosol can cover the global atmosphere within a few weeks to months. These remain for several years and affect atmospheric circulation causing surface temperature to fall in many regions. Effects include temporary reductions in light levels and severe and unseasonable weather (including cool summers and colder-than-normal winters). Some aspects of the understanding and prediction of super-eruptions are problematic because they are well outside modern experience. Our global society is now very different to that affected by past, modest-sized volcanic activity and is highly vulnerable to catastrophic damage of infrastructure by natural disasters. Major disruption of services that society depends upon can be expected for periods of months to, perhaps, years after the next very large explosive eruption and the cost to global financial markets will be high and sustained.

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Lunt, Daniel J., Alan M. Haywood, Gavin L. Foster, and Emma J. Stone. "The Arctic cryosphere in the Mid-Pliocene and the future." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 367, no. 1886 (October 13, 2008): 49–67. http://dx.doi.org/10.1098/rsta.2008.0218.

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The Mid-Pliocene ( ca 3 Myr ago) was a relatively warm period, with increased atmospheric CO 2 relative to pre-industrial. It has therefore been highlighted as a possible palaeo-analogue for the future. However, changed vegetation patterns, orography and smaller ice sheets also influenced the Mid-Pliocene climate. Here, using a general circulation model and ice-sheet model, we determine the relative contribution of vegetation and soils, orography and ice, and CO 2 to the Mid-Pliocene Arctic climate and cryosphere. Compared with pre-industrial, we find that increased Mid-Pliocene CO 2 contributes 35 per cent, lower orography and ice-sheet feedbacks contribute 42 per cent, and vegetation changes contribute 23 per cent of Arctic temperature change. The simulated Mid-Pliocene Greenland ice sheet is substantially smaller than that of modern, mostly due to the higher CO 2 . However, our simulations of future climate change indicate that the same increase in CO 2 is not sufficient to melt the modern ice sheet substantially. We conclude that, although the Mid-Pliocene resembles the future in some respects, care must be taken when interpreting it as an exact analogue due to vegetation and ice-sheet feedbacks. These act to intensify Mid-Pliocene Arctic climate change, and act on a longer time scale than the century scale usually addressed in future climate prediction.

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Journal articles on the topic 'Atmospheric circulation Mathematics'

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