A low order dynamical model for runoff predictability     

Olson  Roman  Timmermann  Axel  Lee  June-Yi  An  Soon-Il 《Climate Dynamics》2021,56(1-2):399-422

Climate Dynamics - Recent work has identified potential multi-year predictability in soil moisture (Chikamoto et al. in Clim Dyn 45(7–8):2213–2235, 2015). Whether this long-term...  相似文献   

Redshift evolution of angular diameters and surface brightness: how rigid are galactic measuring rods?     

Roman Tomaschitz 《Astrophysics and Space Science》2011,331(2):397-408

The effect of a cosmic time variation of Newton’s constant on galactic angular diameters, linear size, apparent magnitude, and surface brightness is investigated. The redshift scaling of the gravitational constant is proportional to the Hubble parameter, derived from the constancy of a moderate dimensionless ratio of fundamental constants, and manifested in galactic linear-size evolution. The latter is demonstrated by fitting the angular size–redshift relation to spectroscopically and photometrically selected samples of high-redshift rotators. The intrinsic luminosity evolution of the rotators and their magnitude–redshift and surface brightness–redshift relations are studied. The galactic luminosity scales with a power of the Hubble parameter, and the scaling exponent is inferred from a moderate dimensionless ratio involving the gravitational constant, the Galactic luminosity, and the velocity of the Galaxy in the microwave background. The fits are performed with a cosmic expansion factor derived from paleoplanetary surface temperatures. This expansion factor is tested by comparing the corresponding redshift evolution of the angular-size distance to the distance estimates of two samples of galaxy clusters.  相似文献   

Orbital structure of the GJ876 extrasolar planetary system based on the latest Keck and HARPS radial velocity data     

Roman V. Baluev 《Celestial Mechanics and Dynamical Astronomy》2011,111(1-2):235-266

We use full available array of radial velocity data, including recently published HARPS and Keck observatory sets, to characterize the orbital configuration of the planetary system orbiting GJ876. First, we propose and describe in detail a fast method to fit perturbed orbital configuration, based on the integration of the sensitivity equations inferred by the equations of the original N-body problem. Further, we find that it is unsatisfactory to treat the available radial velocity data for GJ876 in the traditional white noise model, because the actual noise appears autocorrelated (and demonstrates non-white frequency spectrum). The time scale of this correlation is about a few days, and the contribution of the correlated noise is about 2 m/s (i.e., similar to the level of internal errors in the Keck data). We propose a variation of the maximum-likelihood algorithm to estimate the orbital configuration of the system, taking into account the red noise effects. We show, in particular, that the non-zero orbital eccentricity of the innermost planet d, obtained in previous studies, is likely a result of misinterpreted red noise in the data. In addition to offsets in some orbital parameters, the red noise also makes the fit uncertainties systematically underestimated (while they are treated in the traditional white noise model). Also, we show that the orbital eccentricity of the outermost planet is actually ill-determined, although bounded by ~0.2. Finally, we investigate possible orbital non-coplanarity of the system, and limit the mutual inclination between the planets b and c orbits by 5°?C15°, depending on the angular position of the mutual orbital nodes.  相似文献   

Regularization of the circular restricted three-body problem using ‘similar’ coordinate systems     

R. Roman  I. Szücs-Csillik 《Astrophysics and Space Science》2012,338(2):233-243

The regularization of a new problem, namely the three-body problem, using ‘similar’ coordinate system is proposed. For this purpose we use the relation of ‘similarity’, which has been introduced as an equivalence relation in a previous paper (see Roman in Astrophys. Space Sci. doi:, 2011). First we write the Hamiltonian function, the equations of motion in canonical form, and then using a generating function, we obtain the transformed equations of motion. After the coordinates transformations, we introduce the fictitious time, to regularize the equations of motion. Explicit formulas are given for the regularization in the coordinate systems centered in the more massive and the less massive star of the binary system. The ‘similar’ polar angle’s definition is introduced, in order to analyze the regularization’s geometrical transformation. The effect of Levi-Civita’s transformation is described in a geometrical manner. Using the resulted regularized equations, we analyze and compare these canonical equations numerically, for the Earth-Moon binary system.  相似文献   

Thermodynamics with rotation motions: Fragmentation and slip     

Eugeniusz Majewski  Roman Teisseyre 《Acta Geophysica》2013,61(2):281-310

Basing on the Asymmetric Continuum Theory, we develop the thermodynamics including fragmentation spin fracture processes; applications for the earthquake source processes are considered. The fracture band model is used to describe a dislocation and disclination superlattice. The Gibbs free energy of defect formation is specified. A dynamic spin fracture criterion was formulated. Consequently, a dynamic model of rock fracture employing dislocations, disclinations, and cracks was constructed to describe slip and fragmentation fracture processes in the earthquake sources.  相似文献   

Spectrum of hot water in the 4750–13 000 cm⁻¹ wavenumber range (0.769–2.1 μm)     

Nikolai F. Zobov  Sergei V. Shirin  Roman I. Ovsyannikov  Oleg L. Polyansky  Robert J. Barber  Jonathan Tennyson  Peter F. Bernath  Michel Carleer  Reginald Colin  Pierre-François Coheur 《Monthly notices of the Royal Astronomical Society》2008,387(3):1093-1098

The high resolution laboratory spectrum of hot water vapour has been recorded in the 500–13 000 cm⁻¹ wavenumber range and we report on the analysis of the 4750–13 000 cm⁻¹ (0.769–2.1 μm) portion. The emission spectrum was recorded using an oxy-acetylene welding torch and a Fourier transform spectrometer. Line assignments in the laboratory spectrum as well as in an absorption spectrum of a sunspot umbra were made with the help of the BT2 line-list. Our torch spectrum is the first laboratory observation of the 9300 Å'steam bands' seen in M-stars and brown dwarfs.  相似文献   

Evaluation of the Interpretation of Ceilometer Data with RASS and Radiosonde Data   总被引：1，自引：0，他引：1  

Stefan Emeis  Klaus Sch?fer  Christoph Münkel  Roman Friedl  Peter Suppan 《Boundary-Layer Meteorology》2012,143(1):25-35

Since 2006 different remote monitoring methods for determining mixing-layer height have been operated in parallel in Augsburg (Germany). One method is based on the operation of eye-safe commercial mini-lidar systems (ceilometers). The optical backscatter intensities recorded with ceilometers provide information about the range-dependent aerosol concentration; gradient minima within this profile mark the tops of mixed layers. Special software for these ceilometers provides routine retrievals of lower atmospheric layering. A second method, based on sodar observations, detects the height of a turbulent layer characterized by high acoustic backscatter intensities due to thermal fluctuations and a high variance of the vertical velocity component. This information is extended by measurements with a radio-acoustic sounding system (RASS) that directly provides the vertical temperature profile from the detection of acoustic signal propagation and thus temperature inversions that mark atmospheric layers. Ceilometer backscatter information is evaluated by comparison with parallel measurements. Data are presented from 2 years of combined ceilometer and RASS measurements at the same site and from comparison with a nearby (60 km) radiosonde for larger-scale humidity information. This evaluation is designed to ensure mixing-layer height monitoring from ceilometer data more reliable.  相似文献   

Toward a physically plausible upper bound of sea-level rise projections   总被引：3，自引：1，他引：2  

Ryan L. Sriver  Nathan M. Urban  Roman Olson  Klaus Keller 《Climatic change》2012,115(3-4):893-902

Anthropogenic sea-level rise (SLR) causes considerable risks. Designing a sound SLR risk-management strategy requires careful consideration of decision-relevant uncertainties such as the reasonable upper bound of future SLR. The recent Intergovernmental Panel on Climate Change’s (IPCC) Fourth Assessment reported a likely upper SLR bound in the year 2100 near 0.6 m (meter). More recent studies considering semi-empirical modeling approaches and kinematic constraints on glacial melting suggest a reasonable 2100 SLR upper bound of approximately 2 m. These recent studies have broken important new ground, but they largely neglect uncertainties surrounding thermal expansion (thermosteric SLR) and/or observational constraints on ocean heat uptake. Here we quantify the effects of key parametric uncertainties and observational constraints on thermosteric SLR projections using an Earth system model with a dynamic three-dimensional ocean, which provides a mechanistic representation of deep ocean processes and heat uptake. Considering these effects nearly doubles the contribution of thermosteric SLR compared to previous estimates and increases the reasonable upper bound of 2100 SLR projections by 0.25 m. As an illustrative example of the effect of overconfidence, we show how neglecting thermosteric uncertainty in projections of the SLR upper bound can considerably bias risk analysis and hence the design of adaptation strategies. For conditions close to the Port of Los Angeles, the 0.25 m increase in the reasonable upper bound can result in a flooding-risk increase by roughly three orders of magnitude. Results provide evidence that relatively minor underestimation of the upper bound of projected SLR can lead to major downward biases of future flooding risks.  相似文献   

Sulphur solubility in andesitic to basaltic melts: implications for Hekla volcano     

Séverine Moune  François Holtz  Roman E. Botcharnikov 《Contributions to Mineralogy and Petrology》2009,157(6):691-707

The solubility of sulphur in sulphide-saturated, H₂O-bearing basaltic–andesitic and basaltic melts from Hekla volcano (Iceland) has been determined experimentally at 1,050°C, 300 and 200 MPa, and redox conditions with oxygen fugacity (logfO₂) between QFM−1.2 and QFM+1.1 (QFM is a quartz–fayalite–magnetite oxygen buffer) in the systems containing various amounts of S and H₂O. The S content of the H₂O-rich glasses saturated with pyrrhotite decreases from 2,500 ppm in basalt to 1,500 ppm in basaltic andesite at the investigated conditions. Furthermore, the reduction of water content in the melt at pyrrhotite saturation and fixed T, P and redox conditions leads to a decrease in S concentration from 2,500 to 1,400 ppm for basaltic experiments (for H₂O decrease from 7.8 to 1.4 wt%) and from 1,500 to 900 ppm (for H₂O decrease from 6.7 to 1.7 wt%) for basaltic andesitic experiments. Our experimental data, combined with silicate melt inclusion investigations and the available models on sulphide saturation in mafic magmas, indicate that the parental basaltic melts of Hekla were not saturated with respect to sulphide. During magmatic differentiation, the S content in the residual melts increased and might have reached sulphide saturation with 2,500 ppm dissolved S. With further magma crystallization, the S concentration in the melt was controlled by the sulphide saturation of the magma, decreasing from ~2,500 to 900 ppm S.  相似文献   

Moldavites from the Cheb Basin, Czech Republic     

Roman Skála  Ladislav Strnad  Miroslav ?ada 《Geochimica et cosmochimica acta》2009,73(4):1145-2158

Between 1993 and 2007, an estimated 2500-3000 individual moldavite pieces have been found in the Tertiary Cheb Basin, Western Bohemia. This identifies the area as the third most prominent source of Central European tektites, next to the South Bohemian and West Moravian strewn subfields. Basic macroscopic physical properties (weight, shape, color and sculpture) were evaluated for over 350 individual finds of tektites from 4 different localities in the Cheb Basin. All these properties are similar to those observed for the South Bohemian moldavites, particularly with respect of color and weight distribution. In total, 24 tektites from the Cheb Basin have been characterized chemically using electron microprobe. For comparison, a set of 17 moldavites from the South-Bohemian and Moravian strewn subfields was measured as well. Contents of major elements overlap between the two sample sets; the largest variation was observed for iron. The trends observed in the Harker plots, however, seem to differentiate several partial subgroups, some of them characteristic for Cheb tektites only. These results are also substantiated by cluster analysis, which reveals a tight group for most of the tektites from the Cheb Basin, forming two partial clusters. The rest of the Cheb moldavites cluster with the South Bohemian samples. Minor and trace elements were measured with an LA-ICP-MS technique; CI-normalized REE patterns compare well with those for other moldavites. Many tektites, both from Cheb and South Bohemia or Moravia, display considerable heterogeneity: they frequently show schlieren and fluidal fabric. Two samples of this kind from the Cheb Basin showed considerable enrichment in volatile elements (e.g., Zn and Cu), which is typical for Muong Nong-type Australasian tektites. Mössbauer spectroscopy confirmed the highly reducing character of 5 studied moldavites. Discovery of a new moldavite strewn subfield around Cheb substantiates the theory that moldavites were ejected from the Ries impact structure in a fan-shaped jet, although it is not clear yet if it was continuous or composed of individual rays. In addition, the chemistry of the Cheb moldavites indicates significant precursor material heterogeneity.  相似文献