Spatial Distribution Of Anomalies Research Articles

Winter Currents Velocity and Sea Surface Temperature Anomalies Accompanying the Gulf Stream North Wall Displacements

Based on average monthly data of the ORAS4 ocean reanalysis, the spatial distribution and values of anomalies of the ocean surface temperature and the velocity of surface currents occurring in the North Atlantic at the meridional displacements of the north wall of the Gulf Stream in January–February are determined. Gulf Stream North Wall Index data are used as data on Gulf Stream movements. The spatial distributions of anomalies corresponding to the northern and southern positions of the North Wall are based on averaging the fields of ocean surface temperature and the velocity of currents corresponding to each phase of the Gulf Stream North Wall index. It has been revealed that for meridional displacements of the North Wall of the Gulf Stream, statistically significant anomalies of the modulus of current velocity (0.03 m/s) and ocean surface temperature (1°C) are not only in the area of the Wall, but also along the entire northern boundary of the Gulf Stream. Here the value of the correlation coefficient of velocity time series with the Gulf Stream North Wall index is 0.56. As for temperature, the same coefficient is 0.50. Significant temperature anomalies (0.3°C) are found off the coast of the Iberian Peninsula and in the central part of the subtropical gyre. The values of the correlation coefficients of time series of the surface temperature and the index of the Gulf Stream in these areas are 0.48 and 0.53 respectively.

Geophysical characterization of buried active faults: the Concud Fault (Iberian Chain, NE Spain)

The Concud Fault is a ~14-km-long active fault that extends close to Teruel, a city with about 35,000 inhabitants in the Iberian Range (NE Spain). It shows evidence of recurrent activity during Late Pleistocene time, posing a significant seismic hazard in an area of moderate-to-low tectonic rates. A geophysical survey was carried out along the mapped trace of the southern branch of the Concud Fault to evaluate the geophysical signature from the fault and the location of paleoseismic trenches. The survey identified a lineation of inverse magnetic dipoles at residual and vertical magnetic gradient, a local increase in apparent conductivity, and interruptions of the underground sediment structure along GPR profiles. The origin of these anomalies is due to lateral contrast between both fault blocks and the geophysical signature of Quaternary materials located above and directly south of the fault. The spatial distribution of anomalies was successfully used to locate suitable trench sites and to map non-exposed segments of the fault. The geophysical anomalies are related to the sedimentological characteristics and permeability differences of the deposits and to deformation related to fault activity. The results illustrate the usefulness of geophysics to detect and map non-exposed faults in areas of moderate-to-low tectonic activity where faults are often covered by recent pediments that obscure geological evidence of the most recent earthquakes. The results also highlight the importance of applying multiple geophysical techniques in defining the location of buried faults.

Systems of Lineaments of Magnetic and Gravity Anomalies in the Zone of Convergent Interaction of the Amur and the Eurasian Tectonic Plates

We studied the spatial distribution of anomalies of the gravitational and the magnetic fields at the border between the Amur and the Eurasian plates. Methods of statistical analysis showed that the systems of anomalies of geophysical fields fit into the regular spatial structures and are controlled by lineaments of latitude, longitude and diagonal stretch, as well as zones of plastic-elastic flow of rocks (shear-zone). These facts allowed us to establish time of formation of the orthogonal system of geophysical fields anomalies in the strike azimuths (84-354 0 ). As a result of comparing diagonal system of geophysical fields anomalies with spatial distribution of the fields of contemporary seismicity and epicenters of strong earthquakes, an assumption was made that the diagonal system of lineaments fit into zones of tectonic deformation and has been controlling the epicentral fields of contemporary seismicity since the Mesozoic period of seismotectonic activation. The main result of this study is the synthesis of early scientific works and getting new ideas about the spatial distribution of anomalies of geophysical fields. Establishing the sequence of forming isolated systems of anomalies and relationships between geophysical fields and seismicity is the subject of further research.

Extreme climatic events in the Republic of Tuva according to tree-ring analysis

This paper presents results of the spatial distribution of anomalies (disturbances) in the anatomical structure of the annual and missing rings of Siberian larch at the upper forest line in the Republic of Tuva. The spatial analysis of tree-ring chronologies that was conducted on six sites (Mongun, Kolchan, Tan, Derzik, Kungur, and Taris) has made it possible to identify the extreme events of local (1662, 1699, 1792, 1804, 1814, 1821, 1847, 1867, and 1993), regional (1698, 1754, 1775, 1779, 1785, 1788, 1789, 1797, 1813, 1819, 1843, 1854, 1869, 1870, 1882, 1911, and 1923), and interregional (1783, 1784, 1812, and 1884) importance; the latter are in good agreement with the data on large volcanic eruptions (the Grimsvotn, Lakagigar, Soufriere St. Vincent, and Krakatau volcanoes) and data from historical sources.

Calculation of the piezomagnetic field arising from uniform regional stress in inhomogeneously magnetized crust

AbstractThis paper describes a simple procedure for the calculation of the piezomagnetic field arising from uniform regional stress in heterogeneously magnetized crust. There exists a strong similarity between the spatial distributions of anomalies in the geomagnetic total force values arising from magnetization structures in the Earth’s crust and those arising from piezomagnetic signals that arise from there. This similarity enables us to compute the piezomagnetic field due to uniform regional stress without the need to determine the explicit structure of magnetization intensities in the crust. This situation is similar to that of “reduction to the pole”, which is commonly used to interpret magnetic survey data. An explicit formula is presented that gives the 2-D spectrum of the piezomagnetic field from that of local magnetic anomalies; the formula is then applied to synthetic data. Calculated values are compared with the exact solution of the piezomagnetic field in order to assess the efficacy of the proposed method. The comparison verifies that calculations performed using the formula yield sufficiently accurate values for practical use.

Spatial and temporal anomalies of chlorophyll concentration in atlantic ocean (by space-based data)

The work presents long-standing CZCS-satellite-based data about spatial distribution of anomalies in chlorophyll concentration and temperature of the ocean. An anomaly criterion is proposed. Maps of Atlantic ocean areas with elevated probability of anomalies are given. Properties of anomalous zones in different parts of the Atlantic ocean are discussed. Satellite-based maps of anomaly coefficients for chlorophyll concentration and temperature in the Atlantic ocean have been shown to feature substantial differences, the zones of elevated anomaly of chlorophyll concentration and temperature — to be close only in the vicinity of the Amazon outflow into the Atlantic ocean. Along with fundamental knowledge about dynamics of biological phenomena in the ocean the methods described may be used to reveal deviations due to anthropogenic impact. The methods presented may be used to process SeaWiFS program data. The data derived may be used to analyze long-standing time series to estimate randomness of current changes.