Growth in the atmospheric aerosol concentration as a climate forcing agent

The level of scattered radiation is analyzed using data of diurnal solar coronograph observations at the Mountain Astronomic Station in the period 1957?C2010 around coronal spectral lines at 5303 ? and 6374 ?. The observations were performed near the solar limb and were normalized by the intensity of the solar disk center. The measurements revealed variations on different timescales: seasonal variations, local maxima on timescales of a few years, and long-term trends. The local changes in the level of scattered radiation were found to be probably due to volcanic eruptions. An analysis revealed a tendency towards an increased in scattered radiation by approximately 40% during the last 50 years. The variations in the level of scattered radiation are compared with the concentration of atmospheric aerosols. The long-term growth in scattered radiation compares well with changes in the Earth??s near-surface temperature and is possibly associated with global climate change.     

Textural studies on red sediments of Bhimunipatnam,Andhra Pradesh,east coast of India

The study presents the textural characteristics of late Quaternary red sediments of Bhimunipatnam to understand the process of formation of these sediments. The red sediments are classified into (a) yellow sediments (b) reddish brown sediments (c) brick red sediments and (d) light yellow sediments sequence in the vertical litho section. The yellow sediments, rests on the khondalite basement, comprises of medium grained, moderate to poorly sorted and positively skewed. The rounded pebble beds with trough cross bedding indicate high energy turbulent conditions of deposition. The fining upward sequences indicate sediments were deposited under decreasing energy conditions under fluvial regime.The iron bearing minerals like garnets and pyriboles have undergone chemical weathering under high oxidizing environment resulting in addition of silt and clay to the reddish brown and brick red sediments and concretions were formed by carbonate precipitation. These processes caused changes in the mean grain size and sorting nature of these sediments which are originally aeolian in origin. The light yellow sediments were medium to fine grained, well sorted and similar to modern dune sands in terms of textural parameters. These sediments were deposited under low oxidation environmental conditions and acquired yellow colour due to Fe hydroxides.     

Analysis and prediction of a catastrophic Indian coastal heat wave of 2015

Heat wave of 2015 over India, a natural disaster with 2500 human deaths, was studied to understand the characteristics, associated atmospheric circulation patterns and to evaluate its predictability. Although temperatures are highest in May over India, occurrence of heat wave conditions over southeast coastal parts of India in May 2015 had been unanticipated. Analyses revealed that isolated region of Andhra Pradesh (AP) had experienced severe heat wave conditions during May 23–27, 2015, with temperatures above 42 °C and the sudden escalation by 7–10 °C within a short span of 2–3 days. Short-range weather predictions with Advanced Research Weather Research and Forecasting model at 3-km resolution, up to 72-h lead time, have been found accurate with statistical metrics of small mean absolute error and root-mean-square error and high index of agreement confirming the predictability of the heat wave evolution. Analyses have indicated that regional atmospheric pressure disparities within the Eurasia region, i.e., increased pressure gradient between the Middle East and India, had been responsible for increased northwest wind flow over to northwest India and to southeast India which have advected higher temperatures. Estimates of warm air advection have shown heat accumulation over AP region, due to sea breeze effect. The study led to the conclusion that changing pressure gradients between Middle East and India, enhancement of northwest wind flow with warm air advection and sea breeze effect along southeast coast blocking the free flow have contributed to the observed heat wave episode over coastal Andhra Pradesh.     

Calculating Intraurban Agglomeration of Economic Units with Planar and Network K-Functions: A Comparative Analysis

Abstract

According to recent research, one of the most promising strategies for intraurban job growth lies promoting localized clusters that produce goods and services which are primarily sold within a single city, metropolitan area, or urban region. However, in order to design urban policies to create or reinforce local clusters, the first challenge is to measure in a reliable way the clustering tendencies of different kinds of economic units in intraurban space. The aim is to compare the similarities and differences in results obtained from two methods designed to measure global clustering tendencies (the planar and network K-functions) in terms of characterization, scale, and intensity of intraurban localization patterns for tertiary economic units in a Latin American metropolis. It is concluded that the network K-function is a more appropriate method for measuring agglomeration patterns, scale, and intensity at the intra-urban level.     

Time–frequency analysis to profile hydrological regimes: application to Haiti

Abstract

Comprehensive characterization of its flow rates is prerequisite to a proper understanding and water management of a given hydrological region. Several studies question the soundness of stationarity in time series and suggest the need for a quantification of the events and non-stationary features in flow rate time series. In this study, we combine statistical and time–frequency (TF) analyses to characterize and classify the flow rates of an understudied region, namely Haiti. Wavelet transforms and cyclostationarity analyses were combined with principal component analysis and hierarchical clustering to identify three groups of hydrological regimes in the country, suggesting similar management: (1) relatively stable flow rates with TF behaviour; (2) periodic and strongly seasonal flow rates; and (3) unstable flow rates. We argue that the TF methodology can yield additional information in regard to flow events and multiscale behaviour, even for short records. Flow rate characterization would benefit from the exhaustive approach described here.

EDITOR Z.W. Kundzewicz ASSOCIATE EDITOR E. Toth     

Caesium uptake by Callovian–Oxfordian clayrock under alkaline perturbation

The potential effect of near-field alkaline perturbation in clayrocks on Cs retention was explored. Batch experiments were conducted to measure Cs sorption on Callovian–Oxfordian rock samples in alkaline perturbed conditions. Experimental results evidenced a marked effect of alkaline perturbation on the Cs retention properties of Callovian–Oxfordian rock samples. Using a modelling approach, this effect could be attributed to the competition of K⁺, originating from the alkaline solution, for Cs sorption sites on illite surfaces. Experimental results also showed that Cs sorption tends to increase with time. Additional experiments on a mineralogical assemblage representative of a Callovian–Oxfordian rock/concrete interface after long term alkaline perturbation showed that this mineralogical assemblage has a similar efficiency for Cs uptake as the intact clay rock, showing that long term alkaline perturbation of clayrocks and resulting mineralogical changes do not affect the barrier performance considerably with regard to Cs retention.     

Intelligent seismoacoustic system for monitoring the beginning of anomalous seismic process

An intelligent system for monitoring anomalous seismic processes intended for predicting the beginning of an earthquake by standard ground-based stations is presented. The problem is solved by analyzing the seismoacoustic signals coming from deep layers of the Earth. The signals are detected by acoustic sensors placed at the mouths of deep suspended wells.     

Crystalline complexes of the Tarbagatai block of the Early Caledonian superterrane of Central Asia

The oldest crystalline complexes of the Early Caledonian superterrane of Central Asia were formed in the Early Precambrian. They are exposed in the basement of microcontinents, which represent old cratonic fragments. Among the latters are the crystalline complexes of the Tarbagatai block previously ascribed to the Dzabkhan microcontinent. It was shown that the crystalline complexes of the Tarbagatai block have a heterogeneous structure, consisting of the Early Precambrian and later Riphean lithotectonic complexes. Structurally, the Early Precambrian complexes are made up of tectonic sheets of gneisses, migmatites, and gneiss granites of the Ider Complex that are cut by gabbroanorthosite massif. The Riphean Jargalant Complex comprises alternating hornblende crystalline schists and biotite (sometimes sillimanite-bearing) gneisses with marble horizons. The upper age boundary of the Riphean Complex is determined by the subautochthonous granitoids with age about 810 Ma. The presence of the Riphean high-grade rocks indicates that structures with newly formed crust were formed in the paleooceanic framing of the Early Precambrian blocks of the Rodinia supercontinent by the Mid-Late Riphean. Divergence that began at that time within old Rodinian cratons and caused rifting and subsequent break-up of the supercontinent was presumably changed by convergence in the paleooceanic area.     

Geodynamics of NW India: Subduction, lithospheric flexure, ridges and seismicity

Spectral analysis of digital data of the Bouguer anomaly map of NW India suggests maximum depth of causative sources as 134 km that represents the regional field and coincides with the upwarped lithosphere — asthenosphere boundary as inferred from seismic tomography. This upwarping of the Indian plate in this section is related to the lithospheric flexure due to its down thrusting along the Himalayan front. The other causative layers are located at depths of 33, 17, and 6 km indicating depth to the sources along the Moho, lower crust and the basement under Ganga foredeep, the former two also appear to be upwarped as crustal bulge with respect to their depths in adjoining sections. The gravity and the geoid anomaly maps of the NW India provide two specific trends, NW-SE and NE-SW oriented highs due to the lithospheric flexure along the NW Himalayan fold belt in the north and the Western fold belt (Kirthar -Sulaiman ranges, Pakistan) and the Aravalli Delhi Fold Belt (ADFB) in the west, respectively. The lithospheric flexures also manifest them self as crustal bulge and shallow basement ridges such as Delhi — Lahore — Sagodha ridge and Jaisalmer — Ganganagar ridge. There are other NE-SW oriented gravity and geoid highs that may be related to thermal events such as plumes that affected this region. The ADFB and its margin faults extend through Ganga basin and intersect the NW Himalayan front in the Nahan salient and the Dehradun reentrant that are more seismogenic. Similarly, the extension of NE-SW oriented gravity highs associated with Jaisalmer — Ganganagar flexure and ridge towards the Himalayan front meets the gravity highs of the Kangra reentrant that is also seismogenic and experienced a 7.8 magnitude earthquake in 1905. Even parts of the lithospheric flexure and related basement ridge of Delhi — Lahore — Sargodha show more seismic activity in its western part and around Delhi as compared to other parts. The geoid highs over the Jaisalmer — Ganganagar ridge passes through Kachchh rift and connects it to plate boundaries towards the SW (Murray ridge) and NW (Kirthar range) that makes the Kachchh as a part of a diffused plate boundary, which, is one of the most seismogenic regions with large scale mafic intrusive that is supported from 3-D seismic tomography. The modeling of regional gravity field along a profile, Ganganagar — Chandigarh extended beyond the Main Central Thrust (MCT) constrained from the various seismic studies across different parts of the Himalaya suggests crustal thickening from 35-36 km under plains up to ～56 km under the MCT for a density of 3.1 g/cm³ and 3.25 g/cm³ of the lower most crust and the upper mantle, respectively. An upwarping of ～3 km in the Moho, crust and basement south of the Himalayan frontal thrusts is noticed due to the lithospheric flexure. High density for the lower most crust indicates partial eclogitization that releases copious fluid that may cause reduction of density in the upper mantle due to sepentinization (3.25 g/cm³). It has also been reported from some other sections of Himalaya. Modeling of the residual gravity and magnetic fields along the same profile suggest gravity highs and lows of NW India to be caused by basement ridges and depressions, respectively. Basement also shows high susceptibility indicating their association with mafic rocks. High density and high magnetization rocks in the basement north of Chandigarh may represent part of the ADFB extending to the Himalayan front primarily in the Nahan salient. The Nahan salient shows a basement uplift of ～ 2 km that appears to have diverted courses of major rivers on either sides of it. The shallow crustal model has also delineated major Himalayan thrusts that merge subsurface into the Main Himalayan Thrust (MHT), which, is a decollment plane.