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Jacob HaqqMisra; Ravi Kumar Kopparapu; Natasha E. Batalha; Chester E. Harman; James F. Kasting
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The liquid water habitable zone (HZ) describes the orbital distance at which a terrestrial planet can maintain abovefreezing conditions through regulation by the carbonatesilicate cycle. Recent calculations have suggested that planets in the outer regions of the habitable zone cannot maintain stable, warm climates, but rather should oscillate between long, globally glaciated states and shorter periods of climatic warmth. Such conditions, similar to 'Snowball Earth' episodes experienced on...
Topics: Earth and Planetary Astrophysics, Astrophysics, Instrumentation and Methods for Astrophysics,...
Source: http://arxiv.org/abs/1605.07130
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Yantao Yang; Roberto Verzicco; Detlef Lohse
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Vertically bounded fingering double diffusive convection (DDC) is numerically investigated, focusing on the influences of different velocity boundary conditions, i.e. the noslip condition which is inevitable in the labscale experimental research, and the freeslip condition which is an approximation for the interfaces in many natural environments, such as the oceans. For both boundary conditions the flow is dominated by fingers and the global responses follow the same scaling laws, with...
Topics: Fluid Dynamics, Physics, Atmospheric and Oceanic Physics
Source: http://arxiv.org/abs/1602.07718
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Elena Masciadri; Franck Lascaux; Alessio Turchi; Luca Fini
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One of the main goals of the feasibility study MOSE (MOdellig ESO Sites) is to evaluate the performances of a method conceived to forecast the optical turbulence above the ESO sites of the Very Large Telescope and the EuropeanExtremely Large Telescope in Chile. The method implied the use of a dedicated code conceived for the optical turbulence (OT) called AstroMesoNh. In this paper we present results we obtained at conclusion of this project concerning the performances of this method in...
Topics: Astrophysics, Instrumentation and Methods for Astrophysics, Atmospheric and Oceanic Physics, Physics
Source: http://arxiv.org/abs/1612.00711
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O. I. Berngardt; N. P. Perevalova; A. V. Podlesnyi; V. I. Kurkin; G. A. Zherebtsov
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Based on the Irkutsk fast monostatic chirp ionosonde data we made a statistical analysis of ionospheric effects for 28 earthquakes which appeared in 20112016 years. These effects are related with surface (Rayleigh) seismic waves far from epicenter. The analysis has shown that nine of these earthquakes were accompanied by vertical midscale ionospheric irregularities (multicusp). To estimate the ionospheric efficiency of the seismic waves we proposed new index $K_{W}$. The index estimates the...
Topics: Space Physics, Geophysics, Physics, Atmospheric and Oceanic Physics
Source: http://arxiv.org/abs/1609.08366
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Michael Bianco; Peter Gerstoft
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To provide constraints on their inversion, ocean sound speed profiles (SSPs) often are modeled using empirical orthogonal functions (EOFs). However, this regularization, which uses the leading order EOFs with a minimumenergy constraint on their coefficients, often yields low resolution SSP estimates. In this paper, it is shown that dictionary learning, a form of unsupervised machine learning, can improve SSP resolution by generating a dictionary of shape functions for sparse processing (e.g....
Topics: Atmospheric and Oceanic Physics, Data Analysis, Statistics and Probability, Physics, Mathematics,...
Source: http://arxiv.org/abs/1609.04840
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Onno Bokhove; Bin Cheng; Andreas Dedner; Gavin Esler; John Norbury; Matthew R. Turner; Jacques Vanneste; Mike Cullen
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The group focused on a model problem of idealised moist air convection in a single column of atmosphere. Height, temperature and moisture variables were chosen to simplify the mathematical representation (along the lines of the Boussinesq approximation in a height variable defined in terms of pressure). This allowed exact simple solutions of the numerical and partial differential equation problems to be found. By examining these, we identify column behaviour, stability issues and explore the...
Topics: Geophysics, Atmospheric and Oceanic Physics, Physics
Source: http://arxiv.org/abs/1608.05245
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E. Masciadri; B. Neichel; A. Guesalaga; A. Turchi
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Wide Field Adaptive Optics (WFAO) systems represent the more sophisticated AO systems available today at large telescopes. A critical aspect for these WFAO systems in order to deliver an optimised performance is the knowledge of the vertical spatiotemporal distribution of the CN2 and the wind speed. Previous studies (Cortes et al., 2012) already proved the ability of GeMS (the Gemini MultiConjugated AO system) in retrieving CN2 and wind vertical stratification using the telemetry data. To...
Topics: Astrophysics, Instrumentation and Methods for Astrophysics, Atmospheric and Oceanic Physics, Physics
Source: http://arxiv.org/abs/1608.06489
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Grigoris Katsiolides; Eike H. Müller; Robert Scheichl; Tony Shardlow; Michael B. Giles; David J. Thomson
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A common way to simulate the transport and spread of pollutants in the atmosphere is via stochastic Lagrangian dispersion models. Mathematically, these models describe turbulent transport processes with stochastic differential equations (SDEs). The computational bottleneck is the Monte Carlo algorithm, which simulates the motion of a large number of model particles in a turbulent velocity field; for each particle, a trajectory is calculated with a numerical timestepping method. Choosing an...
Topics: Physics, Numerical Analysis, Fluid Dynamics, Atmospheric and Oceanic Physics, Mathematics
Source: http://arxiv.org/abs/1612.07717
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J. F. Muzy; R. Baïle
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We introduce a variant of continuous random cascade models that extends former constructions introduced by BarralMandelbrot and BacryMuzy in the sense that they can be supported by sets of arbitrary fractal dimension. The so introduced sets are exactly selfsimilar stationary versions of random Cantor sets formerly introduced by Mandelbrot as "random cutouts". We discuss the main mathematical properties of our construction and compute its scaling properties. We then illustrate our...
Topics: Data Analysis, Statistics and Probability, Physics, Atmospheric and Oceanic Physics
Source: http://arxiv.org/abs/1601.03775
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Raymond T. Pierrehumbert; Feng Ding
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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 areasthe climate dynamics of atmospheres with a nondilute condensible component, defined as the situation in which a condensible component of the atmosphere makes up a substantial fraction of...
Topics: Earth and Planetary Astrophysics, Astrophysics, Atmospheric and Oceanic Physics, Physics
Source: http://arxiv.org/abs/1608.03294
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It is shown, using results of recent direct numerical simulations, laboratory experiments and atmospheric measurements, that buoyancy driven turbulence exhibits a broad diversity of the types of distributed chaos with its stretched exponential spectrum $\exp(k/k_{\beta})^{\beta}$. The distributed chaos with $\beta = 1/3$ (determined by the helicity correlation integral) is the most common feature of the stably stratified turbulence (due to the strong helical waves presence). These waves mostly...
Topics: Astrophysics, Fluid Dynamics, Solar and Stellar Astrophysics, Physics, Atmospheric and Oceanic...
Source: http://arxiv.org/abs/1608.00489
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Matej Malik; Luc Grosheintz; João M. Mendonça; Simon L. Grimm; Baptiste Lavie; Daniel Kitzmann; ShangMin Tsai; Adam Burrows; Laura Kreidberg; Megan Bedell; Jacob L. Bean; Kevin B. Stevenson; Kevin Heng
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We present the opensource radiative transfer code named HELIOS, which is constructed for studying exoplanetary atmospheres. In its initial version, the model atmospheres of HELIOS are onedimensional and planeparallel, and the equation of radiative transfer is solved in the twostream approximation with nonisotropic scattering. A small set of the main infrared absorbers is employed, computed with the opacity calculator HELIOSK and combined using a correlated$k$ approximation. The molecular...
Topics: Earth and Planetary Astrophysics, Astrophysics, Atmospheric and Oceanic Physics, Physics
Source: http://arxiv.org/abs/1606.05474
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Ding Ma; Pedram Hassanzadeh; Zhiming Kuang
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A linear response function (LRF) that relates the temporal tendency of zonal mean temperature and zonal wind to their anomalies and external forcing is used to accurately quantify the strength of the eddyjet feedback associated with the annular mode in an idealized GCM. Following a simple feedback model, the results confirm the presence of a positive eddyjet feedback in the annular mode dynamics, with a feedback strength of 0.137 day$^{1}$ in the idealized GCM. Statistical methods proposed...
Topics: Fluid Dynamics, Physics, Atmospheric and Oceanic Physics
Source: http://arxiv.org/abs/1608.04130
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Adrean Webb; Takuji Waseda; Wataru Fujimoto; Kazutoshi Horiuchi; Keiji Kiyomatsu; Kazuhiro Matsuda; Yasumasa Miyazawa; Sergey Varlamov; Jun Yoshikawa
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The University of Tokyo and JAMSTEC have conducted stateoftheart wave and current resource assessments to assist with generator site identification and construction in Japan. These assessments are publiclyavailable and accessible via a web GIS service designed by WebBrain that utilizes TDS and GeoServer software with Leaflet libraries. The web GIS dataset contains statistical analyses of wave power, ocean and tidal current power, ocean temperature power, and other basic physical variables....
Topics: Atmospheric and Oceanic Physics, Physics
Source: http://arxiv.org/abs/1607.02251
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Aseel Farhat; Evelyn Lunasin; Edriss S. Titi
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Analyzing the validity and success of a data assimilation algorithm when some state variable observations are not available is an important problem in meteorology and engineering. We present an improved data assimilation algorithm for recovering the exact full reference solution (i.e. the velocity and temperature) of the 3D Planetary Geostrophic model, at an exponential rate in time, by employing coarse spatial mesh observations of the temperature alone. This provides, in the case of this...
Topics: Fluid Dynamics, Atmospheric and Oceanic Physics, Analysis of PDEs, Physics, Mathematics, Geophysics
Source: http://arxiv.org/abs/1608.04770
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The numerical simulation of the nonlinear dynamics of the sea surface has shown that the collision of two groups of relatively low waves with close but noncollinear wave vectors (two or three waves in each group with a steepness of about 0.2) can result in the appearance of an individual anomalous wave whose height is noticeably larger than that in the linear theory. Since such collisions quite often occur on the ocean surface, this scenario of the formation of rogue waves is apparently most...
Topics: Pattern Formation and Solitons, Fluid Dynamics, Nonlinear Sciences, Physics, Atmospheric and...
Source: http://arxiv.org/abs/1602.03753
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Sylvain Robert; Hans R. Künsch
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Ensemble methods such as the Ensemble Kalman Filter (EnKF) are widely used for data assimilation in largescale geophysical applications, as for example in numerical weather prediction (NWP). There is a growing interest for physical models with higher and higher resolution, which brings new challenges for data assimilation techniques because of the presence of nonlinear and nonGaussian features that are not adequately treated by the EnKF. We propose two new localized algorithms based on the...
Topics: Physics, Applications, Atmospheric and Oceanic Physics, Statistics
Source: http://arxiv.org/abs/1605.05476
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D. L. Suhas; Jai Sukhatme
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Quasigeostrophic turbulence on a betaplane with a finite deformation radius is studied nu merically, with particular emphasis on frequency and combined wavenumberfrequency do main analyses. Under suitable conditions, simulations with smallscale random forcing and largescale drag exhibit a spontaneous formation of multiple zonal jets. The first hint of wavelike features is seen in the distribution of kinetic energy as a function of frequency; specifically, for progressively larger...
Topics: Fluid Dynamics, Atmospheric and Oceanic Physics, Physics
Source: http://arxiv.org/abs/1604.01877
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S. V. Prants; A. G. Andreev; M. V. Budyansky; M. Yu. Uleysky
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The seasonal and interannual variability of mesoscale circulation along the eastern coast of the Sakhalin Island in the Okhotsk Sea is investigated using AVISO velocity field and oceanographic data for the period from 1993 to 2016. It is found that mesoscale cyclones with the horizontal dimension of about 100 km occur there predominantly during summer, whereas anticyclones occur predominantly during fall and winter. The cyclones are generated due to the coastal upwelling forced by northward...
Topics: Atmospheric and Oceanic Physics, Physics
Source: http://arxiv.org/abs/1610.08187
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The transport and shear under a Phillipstype spectrum are presented. A combined profile for monochromatic swell and a Phillipstype wind sea spectrum which can be used to investigate the shear under crossing seas is then presented.
Topics: Atmospheric and Oceanic Physics, Physics
Source: http://arxiv.org/abs/1603.06532
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David Collins; Boualem Khouider
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The representation of clouds and associated processes of rain and snow formation remains one of the major uncertainties in climate and weather prediction models. In a companion paper (Part I), we systematically derived a two moment bulk cloud microphysics model for collision and coalescence in warm rain based on the kinetic coalescence equation (KCE) and used stochastic approximations to close the higher order moment terms, and do so independently of the collision kernel. Conservation of mass...
Topics: Atmospheric and Oceanic Physics, Physics
Source: http://arxiv.org/abs/1605.02724
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João M. Mendonça; Simon L. Grimm; Luc Grosheintz; Kevin Heng
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We have designed and developed, from scratch, a global circulation model named THOR that solves the threedimensional nonhydrostatic Euler equations. Our general approach lifts the commonly used assumptions of a shallow atmosphere and hydrostatic equilibrium. We solve the "pole problem" (where converging meridians on a sphere lead to increasingly smaller time steps near the poles) by implementing an icosahedral grid. Irregularities in the grid, which lead to grid imprinting, are...
Topics: Earth and Planetary Astrophysics, Astrophysics, Atmospheric and Oceanic Physics, Physics
Source: http://arxiv.org/abs/1607.05535
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Daniel A. Shaevitz; Ji Nie; Adam H. Sobel
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Devastating floods in northeast Pakistan and northern India occurred in July 2010 and September 2014 as a consequence of extreme precipitation events. The 2010 and 2014 flood events had similar synoptic flow patterns that led to an anomalously high moisture content in the flood region. The quasigeostrophic omega equation is inverted in order to attribute components of the largescale vertical motion profile to synoptic forcing, diabatic heating, and mechanically forced orographic ascent. The...
Topics: Atmospheric and Oceanic Physics, Physics
Source: http://arxiv.org/abs/1603.01317
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Andrea A. Cimatoribus; Hans van Haren
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The relation between the flux of temperature (or buoyancy), the vertical temperature gradient and the height above the bottom, is investigated in an oceanographic context, using highresolution temperature measurements. The model for the evolution of a stratified layer by Balmforth et al. (1998) is reviewed and adapted to the case of a turbulent flow above a wall. Model predictions are compared to the average observational estimates of the flux, exploiting a flux estimation method proposed by...
Topics: Fluid Dynamics, Physics, Atmospheric and Oceanic Physics
Source: http://arxiv.org/abs/1602.02599
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A singlelayer, quasigeostrophic (QG), largescale ocean circulation model is developed in this paper to study available ocean current energy potentials harnessed by using the ocean current turbines. Power extraction is modeled by adding a parameterized Rayleigh friction term in the barotropic vorticity equation. Numerical assessments are performed by simulating a set of midlatitude ocean basins in the beta plane, which are standard prototypes of more realistic ocean dynamics considering...
Topics: Fluid Dynamics, Physics, Atmospheric and Oceanic Physics
Source: http://arxiv.org/abs/1604.08486
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Jacob HaqqMisra; Prabal Saxena; Eric T. Wolf; Ravi Kumar Kopparapu
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The population of known extrasolar planets includes giant and terrestrial planets that closely orbit their host star. Such planets experience significant tidal distortions that can force the planet into synchronous rotation. The combined effects of tidal deformation and centripetal acceleration induces significant asphericity in the shape of these planets, compared to the mild oblateness of Earth, with maximum gravitational acceleration at the poles. Here we show that this latitudinal variation...
Topics: Earth and Planetary Astrophysics, Astrophysics, Instrumentation and Methods for Astrophysics,...
Source: http://arxiv.org/abs/1608.02536
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Takahito Mitsui; Michel Crucifix
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It is well acknowledged that the sequence of glacialinterglacial cycles is paced by the astronomical forcing. However, how much is the sequence robust against natural fluctuations associated, for example, with the chaotic motions of atmosphere and oceans? In this article, the stability of the glacialinterglacial cycles is investigated on the basis of simple conceptual models. Specifically, we study the influence of additive white Gaussian noise on the sequence of the glacial cycles generated...
Topics: Atmospheric and Oceanic Physics, Physics
Source: http://arxiv.org/abs/1611.03295
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Jingfang Fan; Jun Meng; Yosef Ashkenazy; Shlomo Havlin
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We construct directed and weighted climate networks based on near surface air temperature to investigate the global impacts of El Nino and La Nina. We find that regions which are characterized by higher positive or negative network in weighted links, are exhibiting stronger correlations with the El Nino basin and are warmer or cooler during El Nino or La Nina periods. These stronger inweighted activities are found to be concentrated in localized areas, as compared to nonEl Nino periods,...
Topics: Geophysics, Atmospheric and Oceanic Physics, Physics
Source: http://arxiv.org/abs/1609.00547
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The numerical simulation of the nonlinear dynamics of random sea waves at moderately small BenjaminFeir indices and its comparison with the linear dynamics (at the coincidence of spatial Fourier harmonics near a spectral peak at a certain time $t_p$) indicate that the appearance of a rogue wave can be predicted in advance. If the linear approximation shows the presence of a sufficiently extensive and/or high group of waves in the near future after $t_p$, an anomalous wave is almost necessarily...
Topics: Fluid Dynamics, Physics, Atmospheric and Oceanic Physics
Source: http://arxiv.org/abs/1609.00500
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L. De Cruz; J. Demaeyer; S. Vannitsem
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This paper describes a reducedorder quasigeostrophic coupled oceanatmosphere model that allows for an arbitrary number of atmospheric and oceanic modes to be retained in the spectral decomposition. The modularity of this new model allows one to easily modify the model physics. Using this new model, coined "Modular ArbitraryOrder OceanAtmosphere Model" (maooam), we analyse the dependence of the model dynamics on the truncation level of the spectral expansion, and unveil spurious...
Topics: Fluid Dynamics, Chaotic Dynamics, Nonlinear Sciences, Atmospheric and Oceanic Physics, Physics
Source: http://arxiv.org/abs/1603.06755
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The aim of this note is to derive the mixedphase version of the moistair entropy potential temperature $\theta_s$ derived in Marquet (2011). This mixedphase version is suitable to describe parcels where liquid water and ice are allowed to coexist, with possible under or supersaturations, with possible supercooled water and with possible different temperatures for dry air and water vapour, on the one hand, condensed water and ice, on the other hand. The impact of this new mixedphase...
Topics: Geophysics, Fluid Dynamics, Atmospheric and Oceanic Physics, Physics
Source: http://arxiv.org/abs/1605.04382
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Niklas Brännström; Leif Å Persson
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We consider a bilevel optimatisation method for inverse linear atmospheric dispersion problems where both linear and nonlinear model parameters are to be determined. We propose that a smooth weighted Mahalanobis distance function is used and derive sufficient conditions for when the follower problem has local strict convexity. A few toymodels are presented where local strict convexity and illposedness of the inverse problem are explored, indeed the smooth distance function is compared and...
Topics: Atmospheric and Oceanic Physics, Physics
Source: http://arxiv.org/abs/1607.04804
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Alessio Turchi; Elena Masciadri; Luca Fini
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In this paper we study the abilities of an atmospherical mesoscale model in forecasting the classical atmospherical parameters relevant for astronomical applications at the surface layer (wind speed, wind direction, temperature, relative humidity) on the Large Binocular Telescope (LBT) site  Mount Graham, Arizona. The study is carried out in the framework of the ALTA project aiming at implementing an automated system for the forecasts of atmospherical parameters (MesoNh code) and the optical...
Topics: Astrophysics, Instrumentation and Methods for Astrophysics, Atmospheric and Oceanic Physics, Physics
Source: http://arxiv.org/abs/1609.00237
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E. Masciadri; F. Lascaux; A. Turchi; L. Fini
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In this contribution we present the most relevant results obtained in the context of a feasibility study (MOSE) undertaken for ESO. The principal aim of the project was to quantify the performances of a mesoscale model (AstroMesoNH code) in forecasting all the main atmospherical parameters relevant for the groundbased astronomical observations and the optical turbulence (CN2 and associated integrated astroclimatic parameters) above Cerro Paranal (site of the VLT) and Cerro Armazones (site of...
Topics: Astrophysics, Instrumentation and Methods for Astrophysics, Atmospheric and Oceanic Physics, Physics
Source: http://arxiv.org/abs/1608.06506
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Donald B. Percival; Donald W. Denbo; Edison Gica; Paul Y. Huang; Harold O. Mofjeld; Michael C. Spillane; Vasily V. Titov
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A performance measure for a DART tsunami buoy network has been developed. The measure is based on a statistical analysis of simulated forecasts of wave heights outside an impact site and how much the forecasts are degraded in accuracy when one or more buoys are inoperative. The analysis uses simulated tsunami height time series collected at each buoy from selected source segments in the Shortterm Inundation Forecast for Tsunamis (SIFT) database and involves a set for 1000 forecasts for each...
Topics: Statistics, Applications, Atmospheric and Oceanic Physics, Physics
Source: http://arxiv.org/abs/1607.02795
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Alexander M. R. Bakker; Tony E. Wong; Kelsey L. Ruckert; Klaus Keller
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Future sealevel rise poses nontrivial risks for many coastal communities. Managing these risks often relies on consensus projections like those provided by the IPCC. Yet, there is a growing awareness that the surrounding uncertainties may be much larger than typically perceived. Recently published sealevel projections appear widely divergent and highly sensitive to nontrivial model choices and the West Antarctic Ice Sheet (WAIS) may be much less stable than previously believed, enabling a...
Topics: Atmospheric and Oceanic Physics, Physics
Source: http://arxiv.org/abs/1609.07119
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Eugenio Jimenez; Gara Quintana; Pablo Mena; Pablo Dorta; Ivan PerezAlvarez; Santiago Zazo; Marina Perez; Eduardo Quevedo
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The authors present full wave simulations and experimental results of propagation of electromagnetic waves in shallow seawaters. Transmitter and receiver antennas are tenturns loops placed on the seabed. Some propagation frameworks are presented and simulated. Finally, simulation results are compared with experimental ones.
Topics: Atmospheric and Oceanic Physics, Physics
Source: http://arxiv.org/abs/1604.03694
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W. Steven Rosenthal; Shankar C. Venkataramani; Arthur J. Mariano; Juan M. Restrepo
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We show that modifying a Bayesian data assimilation scheme by incorporating kinematicallyconsistent displacement corrections produces a scheme that is demonstrably better at estimating partially observed state vectors in a setting where feature information important. While the displacement transformation is not tied to any particular assimilation scheme, here we implement it within an ensemble Kalman Filter and demonstrate its effectiveness in tracking stochastically perturbed vortices.
Topics: Data Analysis, Statistics and Probability, Physics, Atmospheric and Oceanic Physics
Source: http://arxiv.org/abs/1602.02209
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Proxima Centauri b, an Earthsize planet in the habitable zone of our nearest stellar neighbour, has just been discovered. A theoretical framework of synchronously rotating planets, in which the risk of a runaway greenhouse on the sunlight side and atmospheric collapse on the reverse side are mutually ameliorated via heat transport is discussed. This is developed via simple (tutorial) models of the climate. These show that lower incident stellar flux means that less heat transport, so less...
Topics: Earth and Planetary Astrophysics, Astrophysics, Atmospheric and Oceanic Physics, Physics
Source: http://arxiv.org/abs/1608.07263
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Kevin Günthner; Imran Khan; Dominique Elser; Birgit Stiller; Ömer Bayraktar; Christian R. Müller; Karen Saucke; Daniel Tröndle; Frank Heine; Stefan Seel; Peter Greulich; Herwig Zech; Björn Gütlich; Sabine PhilippMay; Christoph Marquardt; Gerd Leuchs
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The measurement of quantum signals that traveled through long distances is of fundamental and technological interest. We present quantumlimited coherent measurements of optical signals, sent from a satellite in geostationary Earth orbit to an optical ground station. We bound the excess noise that the quantum states could have acquired after having propagated 38600 km through Earth's gravitational potential as well as its turbulent atmosphere. Our results indicate that quantum communication is...
Topics: Quantum Physics, Atmospheric and Oceanic Physics, Emerging Technologies, Physics, Cryptography and...
Source: http://arxiv.org/abs/1608.03511
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Y. Wang; F. J. BeronVera; M. J. Olascoaga
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We document the longterm evolution of an Agulhas ring detected from satellite altimetry using a technique from nonlinear dynamical systems that enables objective (i.e., observerindependent) eddy framing. Such objectively detected eddies have Lagrangian (material) boundaries that remain coherent (unfilamented) over the detection period. The ring preserves a quite compact material entity for a period of about 2 years even after most initial coherence is lost within 5 months after detection. We...
Topics: Plasma Physics, Fluid Dynamics, Atmospheric and Oceanic Physics, Physics
Source: http://arxiv.org/abs/1601.01560
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James B. Elsner; Thomas H. Jagger; Tyler Fricker
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This paper estimates local tornado risk from records of past events using statistical models. First, a spatial model is fit to the tornado counts aggregated in counties with terms that control for changes in observational practices over time. Results provide a longterm view of risk that delineates the main tornado corridors in the United States where the expected annual rate exceeds two tornadoes per 10,000 square km. A few counties in the Texas Panhandle and central Kansas have annual rates...
Topics: Atmospheric and Oceanic Physics, Physics
Source: http://arxiv.org/abs/1606.07325
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D. E. Ruiz; J. B. Parker; E. L. Shi; I. Y. Dodin
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The wave kinetic equation (WKE) describing driftwave (DW) turbulence is widely used in studies of zonal flows (ZFs) emerging from DW turbulence. However, this formulation neglects the exchange of enstrophy between DWs and ZFs and also ignores effects beyond the geometricaloptics limit. We derive a modified theory that takes both of these effects into account, while still treating DW quanta ("driftons") as particles in phase space. The drifton dynamics is described by an equation of...
Topics: Atmospheric and Oceanic Physics, Physics, Plasma Physics
Source: http://arxiv.org/abs/1608.05373
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Darren Engwirda; Maxwell Kelley
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A new, highorder slopelimiting procedure for the Piecewise Parabolic Method (PPM) and the Piecewise Quartic Method (PQM) is described. Following a Weighted Essentially NonOscillatory (WENO)type paradigm, the proposed slopelimiter seeks to reconstruct smooth, nonoscillatory piecewise polynomial profiles as a nonlinear combination of the natural and monotonelimited PPM and PQM interpolants. Compared to existing monotone slopelimiting techniques, this new strategy is designed to improve...
Topics: Fluid Dynamics, Atmospheric and Oceanic Physics, Computational Physics, Numerical Analysis,...
Source: http://arxiv.org/abs/1606.08188
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Earth's atmosphere is in a state far from thermodynamic equilibrium. For example, the large scale equatortopole temperature gradient is maintained by tropical heating, polar cooling, and a midlatitude meridional eddy heat flux predominantly driven by baroclinically unstable weather systems. Based on basic thermodynamic principles, it can be shown that the meridional heat flux, in combination with the meridional temperature gradient, acts to maximize entropy production of the atmosphere. In...
Topics: Atmospheric and Oceanic Physics, Physics
Source: http://arxiv.org/abs/1603.05260
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Bruno Issenmann; Claude Laroche; Eric Falcon
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We experimentally study gravitycapillary wave turbulence on the interface between two immiscible fluids of close density with free upper surface. We locally measure the wave height at the interface between both fluids by means of a highly sensitive laser Doppler vibrometer. We show that the inertial range of the capillary wave turbulence regime is significantly extended when the upper fluid depth is increased: The crossover frequency between the gravity and capillary wave turbulence regimes is...
Topics: Fluid Dynamics, Nonlinear Sciences, Atmospheric and Oceanic Physics, Physics, Classical Physics,...
Source: http://arxiv.org/abs/1610.05899
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Juan M. Restrepo; Shankar C. Venkataramani
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We develop a stochastic parametrization, based on a `simple' deterministic model for the dynamics of steady longshore currents, that produces ensembles that are statistically consistent with field observations of these currents. Unlike deterministic models, stochastic parameterization incorporates randomness and hence can only match the observations in a statistical sense. Unlike statistical emulators, in which the model is tuned to the statistical structure of the observation, stochastic...
Topics: Atmospheric and Oceanic Physics, Data Analysis, Statistics and Probability, Physics, Mathematics,...
Source: http://arxiv.org/abs/1612.01046
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Krzysztof Chalupka; Tobias Bischoff; Pietro Perona; Frederick Eberhardt
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We show that the climate phenomena of El Nino and La Nina arise naturally as states of macrovariables when our recent causal feature learning framework (Chalupka 2015, Chalupka 2016) is applied to microlevel measures of zonal wind (ZW) and sea surface temperatures (SST) taken over the equatorial band of the Pacific Ocean. The method identifies these unusual climate states on the basis of the relation between ZW and SST patterns without any input about past occurrences of El Nino or La Nina....
Topics: Atmospheric and Oceanic Physics, Machine Learning, Artificial Intelligence, Physics, Learning,...
Source: http://arxiv.org/abs/1605.09370
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Joy M. Monteiro; Jai Sukhatme
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The derivation of a quasigeostrophic (QG) system from the rotating shallow water equations on a midlatitude betaplane coupled with moisture is presented. Condensation is prescribed to occur whenever the moisture at a point exceeds a prescribed saturation value. It is seen that a slow condensation time scale is required to obtain a consistent set of equations at leading order. Further, since the advecting wind fields are geostrophic, changes in moisture (and hence, precipitation) occur only...
Topics: Fluid Dynamics, Atmospheric and Oceanic Physics, Physics
Source: http://arxiv.org/abs/1604.03656
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Anna Frishman; Jason Laurie; Gregory Falkovich
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An inverse cascade  energy transfer to progressively larger scales  is a salient feature of twodimensional turbulence. If the cascade reaches the system scale, it creates a coherent flow expected to have the largest available scale and conform with the symmetries of the domain. In a doubly periodic rectangle, the mean flow with zero total momentum was therefore believed to be unidirectional, with two jets along the short side; while for an aspect ratio close to unity, a vortex dipole was...
Topics: Nonlinear Sciences, Fluid Dynamics, Atmospheric and Oceanic Physics, Statistical Mechanics,...
Source: http://arxiv.org/abs/1608.04628