The effect of El Niño Southern Oscillation cycles on the decadal scale suspended sediment behavior of a coastal dry‐summer subtropical catchment

Rivers display temporal dependence in suspended sediment–water discharge relationships. Although most work has focused on multi‐decadal trends, river sediment behavior often displays sub‐decadal scale fluctuations that have received little attention. The objectives of this study were to identify inter‐annual to decadal scale fluctuations in the suspended sediment–discharge relationship of a dry‐summer subtropical river, infer the mechanisms behind these fluctuations, and examine the role of El Niño Southern Oscillation climate cycles. The Salinas River (California) is a moderate sized (11 000 km²), coastal dry‐summer subtropical catchment with a mean discharge (Q_mean) of 11.6 m³ s^?1. This watershed is located at the northern most extent of the Pacific coastal North America region that experiences increased storm frequency during El Niño years. Event to inter‐annual scale suspended sediment behavior in this system was known to be influenced by antecedent hydrologic conditions, whereby previous hydrologic activity regulates the suspended sediment concentration–water discharge relationship. Fine and sand suspended sediment in the lower Salinas River exhibited persistent, decadal scale periods of positive and negative discharge corrected concentrations. The decadal scale variability in suspended sediment behavior was influenced by inter‐annual to decadal scale fluctuations in hydrologic characteristics, including: elapsed time since small (~0.1 × Q_mean), and moderate (~10 × Q_mean) threshold discharge values, the number of preceding days that low/no flow occurred, and annual water yield. El Niño climatic activity was found to have little effect on decadal‐scale fluctuations in the fine suspended sediment–discharge relationship due to low or no effect on the frequency of moderate to low discharge magnitudes, annual precipitation, and water yield. However, sand concentrations generally increased in El Niño years due to the increased frequency of moderate to high magnitude discharge events, which generally increase sand supply. Copyright © 2014 John Wiley & Sons, Ltd.     

Estimation of Surface-Layer Scaling Parameters in the Unstable Boundary Layer: Implications for Orographic Flow Speed-Up

A method is proposed for estimating the surface-layer depth \((z_s)\) and the friction velocity \((u_*)\) as a function of stability (here quantified by the Obukhov length, L) over the complete range of unstable flow regimes. This method extends that developed previously for stable conditions by Argaín et al. (Boundary-Layer Meteorol 130:15–28, 2009), but uses a qualitatively different approach. The method is specifically used to calculate the fractional speed-up \((\varDelta S)\) in flow over a ridge, although it is suitable for more general boundary-layer applications. The behaviour of \(z_s \left( L\right) \) and \(u_*\left( L\right) \) as a function of L is indirectly assessed via calculation of \(\varDelta S\left( L\right) \) using the linear model of Hunt et al. (Q J R Meteorol Soc 29:16–26, 1988) and its comparison with the field measurements reported in Coppin et al. (Boundary-Layer Meteorol 69:173–199, 1994) and with numerical simulations carried out using a non-linear numerical model, FLEX. The behaviour of \(\varDelta S\) estimated from the linear model is clearly improved when \(u_*\) is calculated using the method proposed here, confirming the importance of accounting for the dependences of \(z_s\left( L \right) \) and \(u_*\left( L \right) \) on L to better represent processes in the unstable boundary layer.     

CCD surface photometry of the Seyfert 1 galaxy NGC 4151

We present CCD surface photometry of the central region of the bright Seyfert 1 galaxy NGC 4151. The observations were obtained under excellent seeing conditions (0.75 FWHM). Morphological parameters for the bulge of the galaxy are estimated from the observed broad bandV, R, andI surface brightness profiles.From the analysis of the colour maps two distinct nuclear structures emerge perpendicular to each other. One of them is elliptically elongated at PA angle 50°. This direction is close to the direction of the radio jets and coincides with the Extended Narrow Emission Line Region (ENELR). Its extension is about 7 arc sec and its colours are bluer than the surronding bulge. The second structure is smaller in extension (about 1 arc sec) and is elongated at PA130°. Its colours are redder than those of the surrounding bulge. It is suggested that this might constitute areal extension of the Broad Line Region (BLR).Paper presented at the 11th European Regional Astronomical Meetings of the IAU on New Windows to the Universe, held 3–8 July, 1989, Tenerife, Canary Islands, Spain.     

Space geodesy in geodynamic studies: Recent movements in the Zeya-Bureya Basin

The Amur-Zeya geodynamic test ground was set up in 2000 to study recent intracontinental crustal deformations. The velocity field calculations for the period of 2000 to 2003 describe three movements scales. The general level is characterized by the vectors of IGS sites in the eastern part of Asia, the BLAG (Blagoveshchensk) site included. The southeast movement of the IRKT (Irkutsk) site of the stable Siberian Platform is indicative of deformations in the northeastern part of the Amur Plate. Measurement data on the regional near-latitudinal profile Blagoveshchensk-Sutara, which crosses the Nizhnyaya Zeya Basin, demonstrate a southwestward displacement of the Badzhal-Bureya-Lesser Khingan block relative to the North China block. The dynamic effect of the convergent boundary between the Amur and Okhotsk Sea plates is assumed to extend inland also involving the Zeya-Bureya Basin area. The measurements on the local geodynamic test site relate the deformations of buildings and constructions in the Settlement of Konstantinovka to the mobility of basement faults in the southern part of the Nizhnyaya Zeya Basin. Aseismic deformations are determined by slow horizontal tectonic movements in the junction zone of NNE-trending structures of the latter basin and near-latitudinal faults of the Khailar-Xunhei Belt.     

Using global node-based velocity in random walk particle tracking in variably saturated porous media: application to contaminant leaching from road constructions

Precise and efficient numerical simulation of transport processes in subsurface systems is a prerequisite for many site investigation or remediation studies. Random walk particle tracking (RWPT) methods have been introduced in the past to overcome numerical difficulties when simulating propagation processes in porous media such as advection-dominated mass transport. Crucial for the precision of RWPT methods is the accuracy of the numerically calculated ground water velocity field. In this paper, a global node-based method for velocity calculation is used, which was originally proposed by Yeh (Water Resour Res 7:1216–1225, 1981). This method is improved in three ways: (1) extension to unstructured grids, (2) significant enhancement of computational efficiency, and (3) extension to saturated (groundwater) as well as unsaturated systems (soil water). The novel RWPT method is tested with numerical benchmark examples from the literature and used in two field scale applications of contaminant transport in saturated and unsaturated ground water. To evaluate advective transport of the model, the accuracy of the velocity field is demonstrated by comparing several published results of particle pathlines or streamlines. Given the chosen test problem, the global node-based velocity estimation is found to be as accurate as the CK method (Cordes and Kinzelbach in Water Resour Res 28(11):2903–2911, 1992) but less accurate than the mixed or mixed-hybrid finite element methods for flow in highly heterogeneous media. To evaluate advective–diffusive transport, a transport problem studied by Hassan and Mohamed (J Hydrol 275(3–4):242–260, 2003) is investigated here and evaluated using different numbers of particles. The results indicate that the number of particles required for the given problem is decreased using the proposed method by about two orders of magnitude without losing accuracy of the concentration contours as compared to the published numbers.     

Multivariate analysis of contamination in the mining district of Linares (Jaén, Spain)

Historically, a significant level of mining activity has taken place in the batholite-related metalogenic enclave of Linares (Jaén province, Spain), associated with Pb–Ag, Cu, Zn and Fe sulphides and Ba sulphate mineralization, though mining here has now been abandoned. Additionally, the area features a significant amount of urban, industrial and agricultural activities. These considerations, taken together, explain the need to assess the levels of concentration of trace elements and to determine their relationship with geogenic and anthropogenic factors. For geochemical characterisation of the soil, the region has been divided into 126 grid squares with an area of 1 km². For each grid square, 32 trace elements have been analysed. Elemental concentrations of Cu, Pb, Zn, As and Mn have been included in statistical analyses. According to the reference levels established by the Regional Government (Junta de Andalucía), soils in a large part of the study area require amendment applications. The comparison of the mean content for each grid square with the reference levels reveals a significant degree of contamination of the soil by Cu (719 mg kg⁻¹), Pb (22,964 mg kg⁻¹) and As (100 mg kg⁻¹) in those grid squares affected by metallurgic activities. By means of factor analysis, four scores have been identified which together account for 80% of the variance observed. The first score is highly correlated with the logarithms of the variables Fe, Th, La, Ti, Al, Na, K, Zr, Y, Nb, Be and Sc. It is a “natural” factor that indicates the type of soil matrix (fundamentally granites and, to a lesser degree, Triassic materials). The second score shows high correlation with the logarithms of the variables Mo, Cu, Pb, Zn, Ag, Co, Mn, As, Cd, Sb, Ba, W and Sn, and is the “metallization” factor related to the mineralization that has been exploited. The third score is mainly determined by the logarithms of the variables Sr, Ca and Mg. This is a “natural” factor that indicates a type of carbonate soil matrix (Miocene). Finally, the fourth factor groups the logarithms of the variables Ni, V and Cr, elements that are associated with the combustion of fossil fuels. Analysis of the patterns of each of the factors identified enabled achieving a global characterisation of the study area. Cluster analysis of the observations showed there to be five clusters relating to the grid squares, differentiated by lithologies and degrees of contamination. These clusters are used to determine the background of granite and to calculate the anomalous load.     

Influence of surface heterogeneities of building granite on its thermal response and its potential for the generation of thermoclasty

Surface properties, especially albedo, and aspect are widely accepted as strong influences on the surface thermal response of building stone to insolation. However, the influence that adjacent areas of stone with very different surface properties may have on the thermal response of a patch of stonework, and the ways in which spatial variation in thermal characteristics might enhance stone decay has received relatively little attention. This paper examines the differential thermal response of granite used in construction that results from the presence of dark coloured micro-granular enclaves within a leucocratic host. Surface temperatures and temperature differences between enclaves exhibiting mico-spalling, enclaves with no spalling and the surrounding stone were measured for different aspects and seasons on a 20th century building in Madrid. These data were used to calculate a number of “indices” related to short-term temperature cycling and temperature gradients that have the theoretical capability of generating irreversible deformation of the stone. These indices suggest that micro-spalling of enclaves, compared to a lack of similar decay on the host-rock, is related to their differential thermal response to insolation, most importantly the lower albedo and thermal conductivity values of the enclaves. However, these factors are not sufficient on their own to trigger spalling, and breakdown was only observed where enclaves also experienced repeated, short-term surface temperature cycling caused by, for example, temporary shading by adjacent vegetation. These rapid temperature reversals are identified as a key contributory factor to the thermally driven decay observed on some of the enclaves.     

Influence of the atmospheric conditions on PM<Subscript>10</Subscript> concentrations in Poznań, Poland

This study investigates atmospheric conditions’ influence on the mean and extreme characteristics of PM₁₀ concentrations in Poznań during the period 2006–2013. A correlation analysis was carried out to identify the most important meteorological variables influencing the seasonal dynamics of PM₁₀ concentrations. The highest absolute correlation values were obtained for planetary boundary layer height (r = ?0.57), thermal (daily minimum air temperature: r = ?0.51), anemological (average daily wind speed: r = ?0.37), and pluvial (precipitation occurrence: r = ?0.36) conditions, however the highest correlations were observed for temporal autocorrelations (1 day lag: r = 0.70). As regulated by law, extreme events were identified on the basis of daily threshold value i.e. 50 μg m^?3. On average, annually there are approximately 71.3 days anywhere in the city when the threshold value is exceeded, 46.6 % of those occur in winter. Additionally, 83.7 % of these cases have been found to be continuous episodes of a few days, with the longest one persisting for 22 days. The analysis of the macro-scale circulation patterns led to the identification of an easy-to-perceive seasonal relations between atmospheric fields that favour the occurrence of high PM₁₀ concentration, as well as synoptic situations contributing to the rapid air quality improvement. The highest PM₁₀ concentrations are a clear reaction to a decrease in air temperature by over 3 °C, with simultaneous lowering of PBL height, mean wind speed (by around 1 m s^?1) and changing dominant wind directions from western to eastern sectors. In most cases, such a situation is related to the expansion of a high pressure system over eastern Europe and weakening of the Icelandic Low. Usually, air quality conditions improve along with an intensification of westerlies associated with the occurrence of low pressure systems over western and central Europe. Opposite relations are distinguishable in summer, when air quality deterioration is related to the inflow of tropical air masses originating over the Sahara desert.     

Linking sedimentation rates and large‐scale architecture for facies prediction in nonmarine basins (Paleogene,Almazán Basin,Spain)

This article focuses on the relationships between the large‐scale stratigraphic architecture of the Almazán basin infill and the sedimentation rates (SR) calculated for precise time intervals. Our aim was to improve the understanding of the timing and causes of the architectural changes, their significance in terms of accommodation space and sediment supply and their relationship with climate and tectonics. The study area includes the Gómara fluvial fan, the main sediment transfer system of the Almazán basin during Paleogene times. Its large‐scale architecture shifted through time between a stacking pattern of low density ribbon‐like and high density sheet‐like channel fills. Laterally to the fluvial system, mudstone and evaporitic mudstone units represented evaporitic mudflats which passed laterally into palustrine/lacustrine limestone units interpreted as lakes and ponds. Stacked calcretes occurred in distal alluvial and distal floodplain settings. A magnetostratigraphy encompassing 2600 m guided by available fossil mammal biochronology has provided a temporal framework that spans the complete Paleogene infill of the basin, from Late Lutetian to Late Oligocene, filling a gap in the Cenozoic chronostratigraphy of Spanish basins. This permits to constrain the kinematics of the structures both in the basin and in its margins, and to provide the timing for the depositional sequences. These data, combined with a magnetostratigraphic map, where magnetic reversals were traced through the Gómara monocline, allow a detailed analysis of the SR variability across the fluvial system and its adjacent depositional environments. The results show that high sedimentation rates (around 30–40 cm kyr^?1) are related to fluvial environments with low density ribbon‐shaped channels, while low SR (around or below 10 cm kyr^?1) are related to high density sheet‐like channels. Laterally, mud dominated environments with high SR (15–20 cm kyr^?1) grade into palustrine/lacustrine carbonated environments with low SR (around 9 cm ky^?1). The lowest SR (about 3 cm kyr^?1) are related to the development of stacked calcrete profiles in distal floodplain and in the connection of distal alluvial and palustrine/lacustrine units.     

Nonlinear magneto-acoustic waves in the solar atmosphere

The weakly nonlinear evolution of quasi-isentropic magnetoacoustic waves in the solar atmosphere is analyzed. The plasma is assumed to be initially homogeneous, in thermal equilibrium and with a straight and homogeneous magnetic field frozen in. Additionally, the plasma is assumed to be cooled by the standard cooling function in the range of 10⁴ K<T<10⁷ K and heated by a mechanism which is proportional to the density and temperature. The range of temperature where the plasma is isentropically unstable, the e-folding time for thermal instability and the corresponding time and length-scale for wave breaking are found.