Moisture rainout fraction over the Indian Ocean during austral summer based on $$^{18}\hbox {O}/{}^{16}\hbox {O}$$ ratios of surface seawater,rainwater at latitude range of 10°N–60°S

Oxygen isotope ratios (\(^{18}\hbox {O}/^{16}\hbox {O}\)) of surface seawater and rainwater samples from the Indian Ocean region (10°N–60°S) during austral summer collected onboard ORV Sagar Nidhi during 2011–2013 have been measured along with salinity, sea surface temperature and relative humidity. The rainwater is isotopically lighter (by \(4.6\pm 2.7\permille )\) compared to the equilibrium condensation of the vapour arising from the seawater at the ambient condition. The isotopic composition of the vapour at high altitude responsible for the rain formation at the sampling location is estimated from a global atmospheric water isotope model (IsoGSM2). The apparent deficit of \(\sim \)5\(\permille \) can be explained by invoking a high degree of rainout (on average, about 70% of the overhead atmospheric moisture) during transport of the source vapour to the sampling location undergoing a Rayleigh fractionation. The required rainout fraction is higher (\(\sim \)80%) in the latitude belt 40°–60°S compared to the equatorial belt (\(\sim \)60%). The pattern of variation in the rainout fraction with latitude is consistent with the well-known evaporation/precipitation processes in the Indian Ocean.     

Pre-earthquake Atmospheric and Ionospheric Anomalies before Taiwan Earthquakes (M 6.1 and M 6.4) on February (4th and 6th), 2018

Geomagnetism and Aeronomy - Satellite measurements are becoming popular among the scientific community to identify earthquake precursors since its spatial coverage is more and round the clock...     

Simulation of Flow in a Complex Aquifer System Subjected to Long-Term Well Network Growth

In west-central Lower Peninsula of Michigan, population growth and expanded agricultural activities over recent decades have resulted in significant increases in distributed groundwater withdrawals. The growth of the extensive well network and anecdotes of water shortages (dry wells) have raised concerns over the region's groundwater sustainability. We developed an unsteady, three-dimensional (3D) groundwater flow model to describe system dynamics over the last 50 years and evaluate long-term impacts of groundwater use. Simulating this large aquifer system was challenging; the site is characterized by strong, spatially distributed, and statistically nonstationary heterogeneity, making it difficult to avoid over-parameterization using traditional approaches for conceptualizing and calibrating a flow model. Moreover, traditional pumping and water level data were lacking and prohibitively expensive to collect given the large-scale and long-term nature of this study. An integrated, stochastic-deterministic approach was developed to characterize the system and calibrate the flow model through innovative use of high-density water well datasets. This approached allowed (1) implementation of a “zone-based,” nonstationary stochastic approach to conceptualize complex spatial variability using a small set of geologic material types; (2) modeling the spatiotemporal evolution of many water well withdrawals across several decades using sector-based parameterization; and (3) critical analysis of long-term water level changes at different locations in the aquifer system for characterizing the system dynamics and calibrating the model. Results show the approach is reasonably successful in calibrating a complex model for a highly complex site in a way that honors complex distributed heterogeneity and stress configurations.     

Impact of internal waves on sound propagation off Bhimilipatnam,east coast of India

Internal waves (IW) are identified off Bhimilipatnam, east coast of India, from the time series CTD (hourly interval) and thermistor chain data (2 min interval) collected during 23–25 Feb 2007. The measurements were carried out at 94 m water depth on the continental shelf edge. These data sets are used to describe the characteristics of IW and their impact on acoustic fields. Garrett and Munk (GM) model has been used to predict the characteristics of low frequency (LF) IW with space and time. Active IW are seen in the layers 54 m–94 m with a velocity of 0.548 km h⁻¹ and the wavelengths of the order of 0.03 km–21.8 km. The model could capture the IW features in the thermocline region accurately than at the bottom. This could be due to the limitation of the model which considers linearity. High frequency IW observed at the bottom could be due to the advection of tidal currents over the shallow irregular bottom in the presence of stratification. The study emphasizes linear IW rather than transient non-linear waves induced by tidal interaction with topography.     

Geochemistry of Neogene sedimentary rocks from Borneo Basin,East Malaysia: Paleo-weathering,provenance and tectonic setting

Multi-element geochemistry and mineralogy are used to characterize the chemical composition, degree of paleo-weathering, provenance and tectonic settings of the Neogene sedimentary rocks of Borneo Basin of east Malaysia. Sedimentary rocks are classified as extremely weathered sandstones (i.e. wacke, arkose, litharenite, Fe-sandstone and quartz arenite). Wacke, arkose, litharenite and Fe-sandstone are characterized by post-depositional K-metasomatism and zircon enrichment through sediment recycling. Geochemical characteristics suggest a mixed-nature provenance for the sandstones and the variable tectonic settings possibly mirror the complexity of the basin. Enriched Cr in quartz arenite and Fe-sandstone are related to the contribution from ophiolite or fractionation of Cr-bearing minerals.     

Chemistry of Tender Coconut Water from the Cuddalore Coastal Region in Tamil Nadu, India

Tender coconut water (TCW) is rich in nutrients, presenting low fat levels, and considered to be an excellent isotonic drink. To understand the chemistry of TCW, samples of TCW with 6–7 and 11–12 months of maturity were collected from the same coconut trees in different locations in the coastal Cuddalore district. It was found that TCW is dominated by K⁺ among cations and by Cl^? among anions. The pH of the TCW was acidic to neutral, with high electrical conductivity. Comparison of the TCW samples with drinking water standards show that the former contained certain ions more than the permissible limit. It was understood that the process of selective absorption by plants or by certain other chemical process taking place during the formation of kernel tissues would alter the chemical composition of coastal TCW in the Cuddalore district.     

Impact of rainfall pattern on interrill erosion process

The impact of rainfall pattern on the interrill erosion process is not fully understood despite its importance. Systematic rainfall simulation experiments involving various rainfall intensities, stages, intensity sequences, and surface cover conditions were conducted in this study to investigate their effects on the interrill erosion process. Five rainfall patterns designed with the same total kinetic energy/precipitation (increasing, decreasing, rising–falling, falling–rising and constant patterns) were randomly delivered to a pre‐wet clay loam soil surface at a 10° slope gradient. Significant differences in soil losses were observed among the different rainfall patterns and stages, but there was no obvious difference in runoff. Kinetic energy flux (KE_r) was a governing factor for interrill erosion, and constant rainfall pattern (CST) produced nine times greater soil loss than runs with no KE_r. Varied‐intensity patterns had a profound effect on raindrop‐induced sediment transport processes; path analysis results indicated that said effect was complex, interactive and intensity‐dependent. Low hydraulic parameter thresholds further indicated that KE_r was the dominant factor in detaching soil particles, while overland flow mainly contributed to transporting the pre‐detached particles. This study not only sheds light on the mechanism of interrill sediment transport capacity and detachability, but also may provide a useful database for developing event‐based interrill erosion prediction models. Copyright © 2017 John Wiley & Sons, Ltd.     

Relativistic magnetofluid disc with nonzero radial velocity in Schwarzschild geometry

In this paper we consider the equilibrium of a magnetofluid disc in Schwarzschild background with an external magnetic field, having the azimuthal and the radial components of the flow velocity nonzero. The electrical conductivityσ of the fluid is taken to be finite and thus the solution for the electromagnetic field is required to satisfy the Ohm’s law too with the four-current having onlyJ ^ϕ andJ ^t nonzero. The various physical parameters that have to correlate for possible equilibrium configurations are identified and their respective magnitudes estimated. It is found that for a given angular momentum distribution the inner edge of the disc can reach well within the usual6m limit only when the surface magnetic field of the central object is not too high when the matter density at the outer edge of the disc and the accretion rate are taken with reasonable limits