Response of a Coupled Ocean�CAtmosphere Model to Greenland Ice Melting

We investigate the transient response of the global coupled ocean?Catmosphere system to enhanced freshwater forcing representative of melting of the Greenland ice sheets. A 50-year long simulation by a coupled atmosphere?Cocean general circulation model (CGCM) is compared with another of the same length in which Greenland melting is prescribed. To highlight the importance of coupled atmosphere?Cocean processes, the CGCM results are compared with those of two other experiments carried out with the oceanic general circulation model (OGCM). In one of these OGCM experiments, the prescribed surface fluxes of heat, momentum and freshwater correspond to the unperturbed simulation by the CGCM; in the other experiment, Greenland melting is added to the freshwater flux. The responses by the CGCM and OGCM to the Greenland melting have similar patterns in the Atlantic, albeit the former having five times larger amplitudes in sea surface height anomalies. The CGCM shows likewise stronger variability in all state variables in all ocean basins because the impact of Greenland melting is quickly communicated to all ocean basins via atmospheric bridges. We conclude that the response of the global climate to Greenland ice melting is highly dependent on coupled atmosphere?Cocean processes. These lead to reduced latent heat flux into the atmosphere and an associated increase in net freshwater flux into the ocean, especially in the subpolar North Atlantic. The combined result is a stronger response of the coupled system to Greenland ice sheet melting.     

Study of Variations of Some Characteristics of the Giant Coronal Hole of 2015–2017

Geomagnetism and Aeronomy - Analysis of images of the full solar disk obtained by ground-based (BST-2, CrAO RAS) and space-based (SDO/AIA, SDO/HMI) instruments and the potential approximation...     

A Study on the Tectonic Characteristics of Shallow Faults in the East of Zhengzhou City

Study on fault activity is a fundamental part of earthquake prediction and earthquake relief in big cities.In the active fault exploration in Zhengzhou,the spatial distribution,geological features and activity of the Huayuankou fault,the Shangjie fault and the Xushui fault were determined using the seismic prospecting method.New understanding about the characteristics of the faults was gained.This provides reliable basic data for future earthquake forecast and earthquake relief work in Zhengzhou.In addition,we proposed some ways to identify fault activity through analyzing the characteristics of the activity of a fault and raised an effective method for exploring active faults in big cities and exploring concealed faults in regions covered with thick overburdens.     

Delineation of a PFOA Plume and Assessment of Data Gaps in its Conceptual Model Using PlumeSeeker™

An accurate conceptual site model (CSM) and plume-delineation at contamination sites are pre-requisites for successful remediation and for satisfying regulators and stakeholders. PlumeSeeker™ is well-suited for assessing data gaps in CSMs by using available site data and for identifying the optimal number and locations of sampling locations to delineate contaminant plumes. It is an enhancement of a university research code for plume delineation using geostatistical and stochastic modeling integrated with the groundwater modeling software MODFLOW-SURFACT™. PlumeSeeker™ increases the overall confidence in the location of the plume boundary through a variance-reduction approach that selects existing- or new monitoring wells for sampling based on minimizing the uncertainty in plume boundary and on new field information. Applicable at sites with or without existing monitoring wells, PlumeSeeker™ is particularly powerful for optimally allocating project resources (labor, well installation, and laboratory costs) between existing wells and sampling at new locations. An application of PlumeSeeker™ at Lakehurst, the naval component of Joint Base McGuire-Dix-Lakehurst in New Jersey, demonstrates how the cost of delineating the migration pathway of a perfluorooctanoic acid (PFOA) plume can be minimized by requiring only 9 new sampling locations in addition to samples from 2 existing wells for achieving a 70% reduction in plume uncertainty. In addition, the use of available site data in three different scenarios identified CSM data-gaps in the source area and in the interaction between Manapaqua Branch and groundwater, where the observed high concentration in this area could have resulted from a combination of groundwater migration and induced infiltration.     

A Probabilistic Estimation of Strong Earthquakes'''' Occurrence in Aeghion Area, Central Greece

INTRODUCTIONTheexaminedareaislocatedintheGulfofCorinthandhasbeenrecognizedasoneofthemostactiveriftsinthewholeAegeanSea .Itsquaternarynormalfaulting (Sebriere ,1 977)anditshighseismicity (PapazachosandPapazachou ,1 997;AmbraseysandJackson ,1 990 )makeitaphysicallaboratorywithintheMediterraneanarea ,wherethephysicalprocessrelatedtotheseismiccyclecouldbestudied .ThecityofAeghionexperiencedastrong (MW =6 4 )earthquakeinJune 1 995,whichcausedseveredamage (Tselentis ,etal.,1 996 ) .Twent…     

Parameter Uncertainty Propagation in a Rainfall–Runoff Model; Case Study: Karoon-III River Basin

Conceptual hydrological models are popular tools for simulating land phase of hydrological cycle. Uncertainty arises from a variety of sources such as input error, calibration and parameters. Hydrologic modeling researches indicate that parametric uncertainty has been considered as one of the most important source. The objective of this study was to evaluate parameter uncertainty and its propagation in rainfall-runoff modeling. This study tried to model daily flows and calculate uncertainty bounds for Karoon-III basin, Southwest of Iran, using HEC-HMS (SMA). The parameters were represented by probability distribution functions (PDF), and the effect on simulated runoff was investigated using Latin Hypercube Sampling (LHS) on Monte Carlo (MC). Three chosen parameters, based on sensitivity analysis, were saturated-hydraulic-conductivity (Ks), Clark storage coefficient (R) and time of concentration (t _c ). Uncertainty associated with parameters were accounted for, by representing each with a probability distribution. Uncertainty bounds was calculated, using parameter sets captured from LHS on parameters PDF of sub-basins and propagating to the model. Results showed that maximum reliability (11%) resulted from Ks propagating. For three parameters, underestimation was more than overestimation. Maximum sharpness and standard deviation (STD) was resulted from propagating Ks. Cumulative Distribution Function (CDF) of flow and uncertainty bounds showed that as flow increased, the width of uncertainty bounds increased for all parameters.     

Can We Improve Estimates of Seismological Q Using a New “Geometrical Spreading” Model?

Precise measurements of seismological Q are difficult because we lack detailed knowledge on how the Earth’s fine velocity structure affects the amplitude data. In a number of recent papers, Morozov (Geophys J Int 175:239–252, 2008; Seism Res Lett 80:5–7, 2009; Pure Appl Geophys, this volume, 2010) proposes a new procedure intended to improve Q determinations. The procedure relies on quantifying the structural effects using a new form of geometrical spreading (GS) model that has an exponentially decaying component with time, e ^?γt·γ is a free parameter and is measured together with Q. Morozov has refit many previously published sets of amplitude attenuation data. In general, the new Q estimates are much higher than previous estimates, and all of the previously estimated frequency-dependence values for Q disappear in the new estimates. In this paper I show that (1) the traditional modeling of seismic amplitudes is physically based, whereas the new model lacks a physical basis; (2) the method of measuring Q using the new model is effectively just a curve fitting procedure using a first-order Taylor series expansion; (3) previous high-frequency data that were fit by a power-law frequency dependence for Q are expected to be also fit by the first-order expansion in the limited frequency bands involved, because of the long tails of power-law functions; (4) recent laboratory measurements of intrinsic Q of mantle materials at seismic frequencies provide independent evidence that intrinsic Q is often frequency-dependent, which should lead to frequency-dependent total Q; (5) published long-period surface wave data that were used to derive several recent Q models inherently contradict the new GS model; and (6) previous modeling has already included a special case that is mathematically identical to the new GS model, but with physical assumptions and measured Q values that differ from those with the new GS model. Therefore, while individually the previous Q measurements have limited precision, they cannot be improved by using the new GS model. The large number of Q measurements by seismologists are sufficient to show that Q values in the Earth are highly laterally variable and are often frequency dependent.     

Surface Soil Effects Study Using Short-period Microtremor Observations in Almería City, Southern Spain

—?In Almería city large earthquakes occurred and many buildings were completely destroyed in these historical earthquakes. The actual population of Almería city is about 200,000 people. This population is rapidly increasing and new urbanizing areas are growing to the eastern part of the city where they are located in softer soil conditions. Consequently, the evaluation of surface soil conditions is very important from a standpoint of earthquake disaster mitigation. We have obtained a landform classification map developed by analysing aerial photos, large-scale topographic maps and 80 borehole data. Eleven unit areas, which have different soil conditions, were inferred from this research. Also, S-wave velocity prospecting tests were carried out at several sites within the city. The shear-velocity values of the ground vary from 1689?m/s in hard rock to 298?m/s in soft soil. These results are useful for understanding the uppermost soil characteristics and are used for soil classification. Finally, short-period microtremor observations were densely carried out in the research area and NAKAMURA's method (1989) was applied for determining predominant periods. Microtremors were observed at about 173 sites with mainly 400?m interval in rock sites and 200?m interval in relatively soft soil sites. From the result of these microtremor measurements, the predominant period determined at rock site, in the western part of the city and historic area, is very short, about 0.1?s, and very stable. However at soft soil sites, in the center of the city, near Zapillo Beach and in the newly developed urban area, the predominant period is about 1.0?s and even larger in concordance with the geological conditions. Finally, at medium soil sites, in the eastern part of the city, the predominant period is about 0.4?s and it appears very stable in the whole region. The difference of predominant periods between hard rock and soft soil sites is very clear and it has been observed that the distribution of predominant periods depends heavily on the surface soil conditions.     

Study of forward–backward solute dispersion profiles in a semi-infinite groundwater system

ABSTRACT

Forward–backward solute dispersion with an intermediate point source in one-dimensional semi-infinite homogeneous porous media is studied in this paper. Solute transport under sorption conditions, first-order decay and zero-order production terms are included. The first type of boundary condition is taken as a constant point source at an intermediate point from where forward and backward solute dispersion is examined. The Laplace transform method is adopted to solve the governing equation analytically. All the analytical results are obtained in graphical form to investigate the forward–backward solute transport in porous media for various hydrological input data. The graphical nature of the analytical solution is compared with numerical data taken from existing literature and similar results are obtained. Also, numerical solution of the governing equation is obtained by the Crank-Nicolson finite difference scheme and validated with the analytical solution, which demonstrates good agreement between them. Accuracy of the solution is also observed by using RMSE.     

Modeling the Mogi magma source centre of the Santorini (Thera) volcano, Aegean Sea, Greece, 1994–1999, based on a numerical-topological approach

The aim of this study is the refinement of the dynamics of a recent (1994?C1999) minor, slow-inflation episode of the Santorini (Thera) volcano, famous for the Minoan (??3600 B.C.) eruption and the identification of the parameters of the magmatic source responsible for the inflation. Based on the Mogi source equations, on geodetic observations of base-line changes, on a topological, grid-search approach and on the reasonable assumption that the magma source remained practically stable in map view during the inflation period, we have been able to refine the location and depth (approximately 2.7 km) of the magma center. A tendency for increase of the magma pressure with time, roughly corresponding to a sphere with radius between 30 and 60 m, and a short deflation interval were also documented. The overall modeling was based on a topological method of inversion in two steps and for a selected 4-D grid. At a first step the system of Mogi-source equations was approximated by the intersection of the 4-D subspaces (defined by sets of grid points) each satisfying one observation equation on the basis of a grid-search procedure. At a second step, the best estimate of the Mogi source solution and its full variance-covariance matrix were defined using a common stochastic approach. The overall approach leads to a solution of a system of equations focusing on a 4-D space bounding significant minima in the misfits between model and observed values, and not on solutions focusing on single points, usually trapped in local minima. This study is important to understand a new phase of volcanic unrest since January 2011, while the proposed methodology, inspired from traditional navigation methods may be useful for other inversion problems leading to redundant systems of highly non-linear equations with n unknowns (i.e. topological solutions in the n-D space).     

Modeling the ML4.7 mainshock of the February–July 2001 earthquake sequence in Aegion, Greece

An earthquake sequence comprising almost 2000 events occurred in February–July 2001 on the southern coast of the Corinth Gulf.Several location methods were applied to 171 events recorded by the regional network PATNET. The unavailability of S-wave readings precluded from reliable depth determination. For the mainshock of April 8, M_L= 4.7, the depth varied from 0 to 20 km. The amplitude spectra of complete waveforms at three local stations (KER,SER, DES; epicentral distances 17, 26 and 56 km) were inverted between 0.1 and 0.2 Hz for double-couple focal mechanism and also for the depth. The optimum solution (strike 220°, dip 40°, rake ‒160°, and depth of 8 km) was validated by forward waveform modeling.Additionally, the mainshock depth was further supported by the P- and S-wave arrival times from the local short-period network CRLNET (Corinth Rift Laboratory).The scalar seismic moment was 2.5e15 Nm,and the moment rate function was successfully simulated by a triangle of the 0.5 second duration. This is equivalent to a 1–1.5 km fault length, and a static stress drop 2–6 MPa. This value is important for future strong ground motion simulation of damaging earthquakes in Aegion region, whose subevents may be modeled according to the studied event. The T axis of the mainshock (azimuth 176° and plunge 67°), is consistent with the regional direction of extension N10°. However, none of the nodal planes can be associated to an active structure seen at the surface. The relationship of this earthquake sequence with deeper faults (e.g. possible detachment at about 10 km) is also unclear.     

A catalog of aftershock sequences in Greece (1971–1997): Their spatial and temporal characteristics

A complete catalog of aftershock sequences is provided for main earthquakes with M_L 5.0, which occurred in the area of Greece and surrounding regions the last twenty-seven years. The Monthly Bulletins of the Institute of Geodynamics (National Observatory of Athens) have been used as data source. In order to get a homogeneous catalog, several selection criteria have been applied and hence a catalog of 44 aftershock sequences is compiled. The relations between the duration of the sequence, the number of aftershocks, the magnitude of the largest aftershock and its delay time from the main shock as well as the subsurface rupture length versus the magnitude of the main shock are calculated. The results show that linearity exists between the subsurface rupture length and the magnitude of the main shock independent of the slip type, as well as between the magnitude of the main shock (M) and its largest aftershock (Ma). The mean difference M–Ma is almost one unit. In the 40% of the analyzed sequences, the largest aftershock occurred within one day after the main shock.The fact that the aftershock sequences show the same behavior for earthquakes that occur in the same region supports the theory that the spatial and temporal characteristics are strongly related to the stress distribution of the fault area.     

Study of Seismic Clusters at Bahía de Banderas Region,Mexico

The coast in the state of Jalisco and south of Nayarit is located within a region of high seismic potential, increasing population, and tourism development. This motivated Civil Defense authorities of Jalisco and the Universidad de Guadalajara to launch in the year 2000 the assessment of the seismic risk of the region. This work focuses in the seismicity study of the area of Bahía de Banderas and northern coast of Jalisco, which is actually a seismic gap. We perform an analysis of available seismograms to characterize active crustal structures, their relationship to surface morphology, and possible extent of these structures into the bay shallow parts. The data consist of waveforms recorded during 2003 when the seismograph network spanned the region. Our method is based on the identification of seismic clusters or families using cross-correlation of waveforms, earthquake relocation and modeling of fault planes. From an initial data set of 404 located earthquakes, 96 earthquakes with M_L < 3.6 are related to 17 potentially active continental structures. We present fault plane model for 11 structures. A subgroup of 7 structures is aligned parallel to the Middle America Trench, as a possible consequence of oblique subduction. The foci of the earthquakes were grouped into clusters corresponding to fault dimensions of hundred of meters, may be considered as asperities or barriers in tectonic structures with lengths between 10 and 30 km. These structures could generate shallow earthquakes with magnitudes between 5.0 and 6.0 and represent an additional seismic threat to the region.     

A physical interpretation of the deterministic fractal–multifractal method as a realization of a generalized multiplicative cascade

In this study, we attempt to offer a solid physical basis for the deterministic fractal–multifractal (FM) approach in geophysics (Puente, Phys Let A 161:441–447, 1992; J Hydrol 187:65–80, 1996). We show how the geometric construction of derived measures, as Platonic projections of fractal interpolating functions transforming multinomial multifractal measures, naturally defines a non-trivial cascade process that may be interpreted as a particular realization of a random multiplicative cascade. In such a light, we argue that the FM approach is as “physical” as any other phenomenological approach based on Richardson’s eddies splitting, which indeed lead to well-accepted models of the intermittencies of nature, as it happens, for instance, when rainfall is interpreted as a quasi-passive tracer in a turbulent flow. Although neither a fractal interpolating function nor the specific multipliers of a random multiplicative cascade can be measured physically, we show how a fractal transformation “cuts through” plausible scenarios to produce a suitable realization that reflects specific arrangements of energies (masses) as seen in nature. This explains why the FM approach properly captures the spectrum of singularities and other statistical features of given data sets. As the FM approach faithfully encodes data sets with compression ratios typically exceeding 100:1, such a property further enhances its “physical simplicity.” We also provide a connection between the FM approach and advection–diffusion processes.     

Characteristics of ChgH–GFP transgenic medaka lines,an in vivo estrogenic compound detection system

We previously reported the characteristics of a ChgH–GFP transgenic medaka line that indicates estrogenic compound pollution in environmental water by the green fluorescence of their liver. Recently, we established four more lines. In this study, the characteristics of the five transgenic medaka lines were investigated. The intensity of reporter gene expression varied among transgenic lines and generally correlated well with the amount of integrated transgene in each line. Line-specific ectopic expression was also observed. However, the sensitivity to 17-β estradiol did not differ among transgenic lines. Three transgenic lines are considered to be suitable as bio-indicators of estrogenic activity, due to the ease of observing green fluorescence in their livers. The transgenic lines can also detect the estrogenic activity of testosterone and 17-β trenbolone at the nominal concentration of 30 and 100 μg/l, respectively.