On characterizing the temporal dominance patterns of model parameters and processes

Diagnostic analyses of hydrological models intend to improve the understanding of how processes and their dynamics are represented in models. Temporal patterns of parameter dominance could be precisely characterized with a temporally resolved parameter sensitivity analysis. In this way, the discharge conditions are characterized, that lead to a parameter dominance in the model. To achieve this, the analysis of temporal dynamics in parameter sensitivity is enhanced by including additional information in a three‐tiered framework on different aggregation levels. Firstly, temporal dynamics of parameter sensitivity provide daily time series of their sensitivities to detect variations in the dominance of model parameters. Secondly, the daily sensitivities are related to the flow duration curve (FDC) to emphasize high sensitivities of model parameters in relation to specific discharge magnitudes. Thirdly, parameter sensitivities are monthly averaged separately for five segments of the FDC to detect typical patterns of parameter dominances for different discharge magnitudes. The three methodical steps are applied on two contrasting catchments (upland and lowland catchment) to demonstrate how the temporal patterns of parameter dynamics represent different hydrological regimes. The discharge dynamic in the lowland catchment is controlled by groundwater parameters for all discharge magnitudes. In contrast, different processes are relevant in the upland catchment, because the dominances of parameters from fast and slow runoff components in the upland catchment are changing over the year for the different discharge magnitudes. The joined interpretation of these three diagnostic steps provides deeper insights of how model parameters represent hydrological dynamics in models for different discharge magnitudes. Thus, this diagnostic framework leads to a better characterization of model parameters and their temporal dynamics and helps to understand the process behaviour in hydrological models. Copyright © 2015 John Wiley & Sons, Ltd.     

Constraints upon models of greenstone belt evolution by gravity modelling,Birch-Uchi greenstone belt,northern Ontario

Eight two-dimensional gravity models, incorporating most of the major hypotheses proposed for the development of Precambrian greenstone belts, are computed. Maximum use is made of geological and geophysical constraints, in an attempt to explain the disparity between the 11 000 m measured stratigraphic thickness and the maximum 5000 m interpreted vertical extent of a portion of the Birch-Uchi metavolcanic-metasedimentary belt.The two-dimensional modelling concentrates on an east-trending profile across a dominantly volcanic portion of the belt comprising three superposed basalt to rhyolite cycles. It is supplemented by a computed second vertical derivative map of the gravity field.Metamorphic and geophysical considerations show simple, isoclinal, parallel folding of the mapped stratigraphic thickness to be unacceptable. Proposed mechanisms which could explain the shallow interpreted vertical extent are a density gradient, a granite root, more complex folding of the belt and restriction of the metavolcanic basin. Taken individually, however, none of these mechanisms is entirely adequate.The model which best fits the gravity and geological data suggests that the shallow vertical extent is the result of both magmatic stoping by a subjacent granitic magma chamber during the caldera stage of cycle III volcanism and partial melting of the basaltic rocks during earlier cycles of volcanism.     

Green's function of one group transport equation for a finite slab of passive and multiplying media by Wiener-Hopf technique

We have applied the method of Wiener-Hopf technique to obtain the Green's functions of one-group transport equations (with anisotropic unit plane source and with isotroic unit plane source) for a finite slab of passive and multiplying media.     

The Sq current system during the International Geophysical Year

Summary. The daily variation for the mean of the eight most quiet days of the IGY is represented as a function of latitude, longitude and UT by means of a spherical harmonic model. The most appropriate choice of Sq baseline is investigated, on the assumption that the external electric currents deduced from the model should be negligible at local midnight. The properties of the final model are discussed, particularly with regard to the external current foci, and are compared with those of previous models.     

On Charged Analogues of Buchdahl’S Type Fluid Spheres

In this article the charged analogues of recently derived Buchdahl’s type fluid spheres have been obtained by considering a particular form of electric field intensity. In this process, Einstein–Maxwell field equations yield eight different classes of solutions, joining smoothly with the exterior Reissner–Nordstrom metric at the pressure free intersurface. Out of the eight solutions only seven could be utilized to represent superdense star models with ultrahigh surface density of the order 2×10¹⁴ gm cm⁻³. The maximum masses of the star models were found to be 8.223931M_Θ and 8.460857M_Θ subject to strong and weak energy conditions, respectively, which are much higher than the maximum masses 3.82M_Θ and 4.57M_Θ allowed in the neutral cases. The velocity of sound seen to be less than that of light throughout the star models.     

Trend in chemical composition of precipitation during 2005–2009 at a rural station of Bhubaneswar, eastern India

Precipitation samples collected during 2005–2009 from a rural forest station of Bhubaneswar were analyzed for their chemical composition. The samples were collected through a wet-only (WO) collector and two bulk (B1 and B2) collectors. The ions were evenly balanced indicating good data quality. The overall pH of rainwater was slightly acidic and ~47% of all rain events during the period were acidic (pH?<?5.6). Multilinear regression analysis showed relation between the free acidity (H⁺) and other components in rainwater. Enrichment factors (EF) of the major components with respect to their sources such as marine and crustal were calculated. Maximum EF was observed for NO ₃ ^? for both marine and crustal sources for all the three collectors. Source apportionments were also carried for the ions. Trend analysis showed continuous increase in most of the ions over years during the study period driven by anthropogenic emissions. Statistical/factorial analysis established correlation among different ions.     

High-resolution satellite image segmentation using Hölder exponents

Texture in high-resolution satellite images requires substantial amendment in the conventional segmentation algorithms. A measure is proposed to compute the Hölder exponent (HE) to assess the roughness or smoothness around each pixel of the image. The localized singularity information is incorporated in computing the HE. An optimum window size is evaluated so that HE reacts to localized singularity. A two-step iterative procedure for clustering the transformed HE image is adapted to identify the range of HE, densely occupied in the kernel and to partition Hölder exponents into a cluster that matches with the range. Hölder exponent values (noise or not associated with the other cluster) are clubbed to a nearest possible cluster using the local maximum likelihood analysis.     

A family of physically realizable perfect fluid spheres representing a quark–stars in general relativity

In the present article, a family of static spherical symmetric well behaved interior solutions is derived by considering the metric potential g ₄₄=B(1−Cr ²)⁻ⁿ for the various values of n, such that (1+n)/(1−n) is positive integer. The solutions so obtained are utilised to construct the heavenly bodies’ like quasi-black holes such as white dwarfs, neutron stars, quarks etc., by taking the surface density 2×10¹⁴ gm/cm³. The red shifts at the centre and on the surface are also computed for the different star models. Moreover the adiabatic index is calculated in each case. In this process the authors come across the quarks star only. Least and maximum mass are fond to be 3.4348M _Θ and 4.410454M _Θ along with the radii 21.0932 km and 23.7245 km respectively.     

Measurement of Kodaikanal White-Light Images – II. Rotation Comparison and Merging with Mount Wilson Data

Sunspot umbral positions and areas were measured for 82 years (1906–1987) of daily, full-disk photoheliogram observations at the Kodaikanal station of the Indian Institute of Astrophysics. The measurement technique and reduction procedures used were nearly identical to those used earlier for the reduction of Mount Wilson daily full-disk photoheliograms, covering an overlapping interval of 69 years. In this paper we compare the differential rotation of the Sun from the analysis of the Kodaikanal data with the Mount Wilson results. In addition, we analyze the data set formed by combining the data from the two sites for differential rotation. While doing this, it has become apparent to us that small, subtle optical effects at both sites produce systematic errors that have an influence on rotation (and other) results from these data. These optical effects are analyzed here, and corrections are made to the positional data of the sunspots from both sites. A data set containing the combined positional data of sunspots from both sites, corrected for these optical aberrations, has been constructed. Results for both sunspot groups and individual sunspots are presented. It is pointed out that optical aberrations similar to those found in the Kodaikanal data may also exist in the Greenwich photoheliograph data, because these two sets of solar images were made with similar telescopes.