The structure of rotating stars from an extension of the Kippenhahn-Thomas method

A method is presented whereby the structure of rotating stars may be determined from an initial guess at the geometry of equipotential surfaces. The method may be considered an extension of the work of Kippenhahn and Thomas in that a uniformly continuous geometry is defined in terms of the appropriate spherical model with Roche characteristics at the surface of the configuration and sphericity at the centre. A simple Cowling model in uniform rotation is employed to illustrate the technique and for comparison purposes with previous work.     

Imperfect fluid Friedmannian cosmology

The bulk viscosity is introduced into the frame of ordinary Friedmannian cosmology (under highly idealized assumption of the constant coefficient of bulk viscosity). Explicit solutions are given for the viscous flat universe filled with the dust-substratum and for the viscous radiative universe. The problem, how does the introduction of viscosity affect the appearance of singularity, is briefly discussed.     

Mass motions in a heated flare filament

Energy transport in a hot flare plasma is examined with particular reference to the influence of fluid motion. On the basis of dimensional considerations the dynamical timescale of the flare plasma is shown to be comparable to the timescale for energy loss by conduction and radiation. It is argued that mass motion is likely to have a profound influence on the evolution of the flare.The detailed response of a flare filament to a localized injection of energy is then analyzed. Radiative, conductive and all dynamical terms are included in the energy equation. Apart from greatly enhancing the rate of propagation of the thermal disturbance through space, mass motion is found to be significant in transferring energy through the moving fluid.Finally the predicted thermal structure is discussed and it is concluded that the presence of mass motions in the flare may be inferred from the form of the soft X-ray differential emission measure.     

Estimate for radiative forcing of smoke aerosol from 2010 summer fires based on measurements in the Moscow region

Temperature and radiation effects of the 2010 summer fires are estimated on the basis of measurements at the Zvenigorod Scientific Station (ZSS) of the Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences (RAS), in the Moscow region. The surface air temperature during the 2010 summer smoke varied in antiphase with the aerosol mass concentration, and the thermal radiation balance in the surface layer of the atmosphere varied in phase. Under extreme smoke of the surface layer in August 2010, the reduction in surface air temperature at ZSS has been found to reach 4 K with an increase in the downward flux of thermal radiation by an average of 20 W/m² and a decrease in the difference between upward and downward fluxes of thermal radiation by an average of 24 W/m².     

Assessing the Hydrochemical Conditions of the Tartar River

The paper gives the results of hydrochemical studies of the Tartar R.—the largest river in Nagornyi Karabakh Republic (NKR). Water quality was assessed with respect to the ecological standards of the Republic of Armenia in terms of major physicochemical characteristics and the concentrations of seven heavy metals. Water quality in the upper reaches of the Tartar R. was referred to the fifth class (poor quality), which is due to the effect of the dumps of the Sotck Gold Deposit and the pollution by agricultural, livestock, and municipal wastewaters. In the lower reaches of the Tartar R., the processes of dilution and self-purification neutralize the adverse effect of pollution sources on water quality, resulting in the improvement of water quality to the class not lower than medium, which is enough for the normal functioning of aquatic ecosystems, fishery, and irrigation. Thus, the Sarang Reservoir, which regulates the Tartar R. runoff, receives good-quality water.     

Probabilistic calibration of a distributed hydrological model for flood forecasting

Abstract

The complexity of distributed hydrological models has led to improvements in calibration methodologies in recent years. There are various manual, automatic and hybrid methods of calibration. Most use a single objective function to calculate estimation errors. The use of multi-objective calibration improves results, since different aspects of the hydrograph may be considered simultaneously. However, the uncertainty of estimates from a hydrological model can only be taken into account by using a probabilistic approach. This paper presents a calibration method of probabilistic nature, based on the determination of probability functions that best characterize different parameters of the model. The method was applied to the Real-time Interactive Basin Simulator (RIBS) distributed hydrological model using the Manzanares River basin in Spain as a case study. The proposed method allows us to consider the uncertainty in the model estimates by obtaining the probability distributions of flows in the flood hydrograph.

Citation Mediero, L., Garrote, L. & Martín-Carrasco, F. J. (2011) Probabilistic calibration of a distributed hydrological model for flood forecasting. Hydrol. Sci. J. 56(7), 1129–1149.