• Volume 123, Issue 8

      December 2014,   pages  1739-1957

    • Impact of global warming on the energetics of lower tropospheric ultra-long waves and the Indian summer monsoon

      M D Chipade J R Kulkarni S M Bawiskar

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      Analyses of 60 years (1949–2008) of monthly energetics of the zonal waves derived from NCEP/NCAR data indicate that ultra-long waves (waves 1 and 2) dominate the spectrum of lower tropospheric zonal waves during monsoon season (June–September). Westerlies over the Indian subcontinent are a source of energy to wave 1. Two oceanic anticyclones, one over Pacific and the other over Atlantic are sources of energy to wave 2. These two waves are inversely correlated. Climatology of the energetics of ultralong waves for the two epochs 1949–1978 (CLP1) and 1979–2008 (CLP2) of 30 years indicates that the intensity of wave 1 has decreased by about 33% whereas the intensity of wave 2 has increased by about 27%. Northward transport of sensible heat during CLP1 changes to southward during CLP2. Larger generation of zonal mean Available Potential Energy (APE) during CLP2 indicates more heating. A larger conversion of kinetic energy (KE) of wave 1 into APE of wave 1 leads to weakening of wave 1 during CLP2. In case of wave 2, lower rate of conversion of KE to APE leads to stronger wave 2 during CLP2. slagging and heating values of the coal has been found in this study.

    • A modified sliding spectral method and its application to COSMIC radio occultation data

      Xian-Sheng Xu Peng Guo Zhen-Jie Hong

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      In the moist lower troposphere, a limitation of the sliding spectral (SS) method is the restriction of the resolution of bending angle profiles because of the atmospheric multipath effect and noise. A modified sliding spectral (MSS) method is proposed in this paper to improve the inversion resolution of SS method in the moist lower troposphere. Simulation results show that the noise in the signal may cause inversion error in the classical SS method. The MSS method can decrease the influence of the noise to some extent. The SS and MSS methods were used to process COSMIC (Constellation Observing System for Meteorology, Ionosphere, and Climate) atmPhs profiles from DOY (day of year) 71–DOY 100 in 2007. The retrieved refractivity profiles were compared with those from the corresponding ECMWF (European Centre for Medium-Range Weather Forecasts) analysis. The results show that the SS method contains systematic positive biases in the 3–10 km height range and systematic negative biases below 3 km. The MSS method, in comparison to SS method, has decreased the maximum positive bias in the range of 3–10 km height from 0.37% to 0.23% in the northern hemisphere, from 1.3% to 0.25% in the tropics, and from 0.60% to 0.35% in the southern hemisphere. The biases of the MSS method are comparable to those announced for the COSMIC atmPrf profile; the latter is inverted by full spectrum inversion (FSI) method.

    • GPU-based normalized cuts for road extraction using satellite imagery

      J Senthilnath S Sindhu S N Omkar

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      This paper presents a GPU implementation of normalized cuts for road extraction problem using panchromatic satellite imagery. The roads have been extracted in three stages namely pre-processing, image segmentation and post-processing. Initially, the image is pre-processed to improve the tolerance by reducing the clutter (that mostly represents the buildings, vegetation, and fallow regions). The road regions are then extracted using the normalized cuts algorithm. Normalized cuts algorithm is a graph-based partitioning approach whose focus lies in extracting the global impression (perceptual grouping) of an image rather than local features. For the segmented image, post-processing is carried out using morphological operations – erosion and dilation. Finally, the road extracted image is overlaid on the original image. Here, a GPGPU (General Purpose Graphical Processing Unit) approach has been adopted to implement the same algorithm on the GPU for fast processing. A performance comparison of this proposed GPU implementation of normalized cuts algorithm with the earlier algorithm (CPU implementation) is presented. From the results, we conclude that the computational improvement in terms of time as the size of image increases for the proposed GPU implementation of normalized cuts. Also, a qualitative and quantitative assessment of the segmentation results has been projected.

    • A Hidden Markov Model for avalanche forecasting on Chowkibal–Tangdhar road axis in Indian Himalayas

      Jagdish Chandra Joshi Sunita Srivastava

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      A numerical avalanche prediction scheme using Hidden Markov Model (HMM) has been developed for Chowkibal–Tangdhar road axis in J&K, India. The model forecast is in the form of different levels of avalanche danger (no, low, medium, and high) with a lead time of two days. Snow and meteorological data (maximum temperature, minimum temperature, fresh snow, fresh snow duration, standing snow) of past 12 winters (1992–2008) have been used to derive the model input variables (average temperature, fresh snow in 24 hrs, snow fall intensity, standing snow, Snow Temperature Index (STI) of the top layer, and STI of buried layer). As in HMMs, there are two sequences: a state sequence and a state dependent observation sequence; in the present model, different levels of avalanche danger are considered as different states of the model and Avalanche Activity Index (AAI) of a day, derived from the model input variables, as an observation. Validation of the model with independent data of two winters (2008–2009, 2009–2010) gives 80% accuracy for both day-1 and day-2. Comparison of various forecasting quality measures and Heidke Skill Score of the HMM and the NN model indicate better forecasting skill of the HMM.

    • Hydrological feasibility of gravity diversion of the west flowing Nethravathi in Karnataka

      Mysooru R Yadupathi Putty N M Thipperudrappa P N Chandramouli

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      The concept of collecting surface runoff on the slopes in canals cut across the western slopes of the Western Ghats, in order to divert part of a flow in the west flowing rivers to the east by gravity, is being promoted in Karnataka. This paper presents a study of the hydrological feasibility of such canals, termed ‘garland canals’ and claimed to be an environmental friendly alternative to the conventional technologies for inter-basin transfer of water, by their promoters. The paper presents a methodology for disaggregating normal annual rainfall into 15-min magnitudes and its application for simulating surface runoff, using a knowledge of infiltration rates on the slopes. The study has been carried out considering a part of a garland canal proposed for diverting the river Netravathi in the state. The results from the study reveal that significant amounts of flow can be collected in the proposed canal only if streams are also tapped and that because of the arrangements necessary for the purpose, garland canals cannot be considered a means superior to the conventional methods for diverting west flowing rivers.

    • Estimation of soil moisture and its effect on soil thermal characteristics at Astronomical Observatory, Thiruvananthapuram, south Kerala

      M S Roxy V B Sumithranand G Renuka

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      Soil moisture is an important parameter of the earth’s climate system. Regression model for estimation of soil moisture at various depths has been developed using the amount of moisture near the surface layer. The estimated values of soil moisture are tested with the measured moisture values and it is found that the estimations are comparable with the observations. The variation of soil thermal properties with the amount of moisture in isohyperthermic ultisols has been investigated at a tropical site in south Kerala for the year 2008. The soil temperatures at 0.05, 0.10, 0.20, 0.30, and 0.50 m depths and soil moisture at 0.05 and 0.10 m are measured using the hydrometeorological data acquisition system installed at the observational site. For soil water contents ranging between 11 and 42% in the soil layer of depth 0.05–0.10 m, the mean values of the heat capacity, thermal diffusivity, thermal conductivity, and thermal admittance obtained were 2.2466 × 10−6 Jm−3K−1, 0.4238 × 10−6 m2s−1, 0.9658 Wm−1K−1, 2.1517 Jm−2s−1/2K−1, respectively. The magnitudes of the diurnal soil thermal parameters showed strong association with the levels of the water content. The thermal diffusivity was found to increase with the amount of soil moisture, up to about 22% of the volumetric water content, but fell as the water content further increases. Similar patterns of the soil moisture levels were noticeable both for the thermal conductivity and admittance.

    • Assessment of groundwater salinity in Nellore district using multi-electrode resistivity imaging technique

      E Chandrasekhar Deshmukh Ramesh Trupti Gurav T K Biswal

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      Multi-electrode resistivity imaging survey with 48 electrodes was carried out to assess the extent of salinity inland, in the shallow subsurface in Nellore district, Andhra Pradesh, in the Eastern Ghats Mobile Belt (EGMB) region. Resistivity data were recorded using Wenner–Schlumberger configuration at nine sites along a profile of about 55 km in length, laid perpendicular to the coast. An average spacing of 6 km is maintained between each site. Assessment of groundwater salinity in the study area was made by joint interpretation of the two-dimensional (2D) geoelectrical models of all the sites together with the geochemical analysis results of water samples and geology. At sites closer to the coast, 2D geoelectrical models of the subsurface indicate low resistivities (2–50 𝛺m) in the depth range from surface up to 15 m. Such low resistivities are due to the high salinity of the groundwater. Geochemical analysis results of water samples at six locations close to the electrical resistivity survey sites also suggest high salinity and high concentrations of total dissolved solids and other chemicals at sites closer to the coast. Away from the coast, the resistivities in the depth range from surface up to 15 m vary in the range of 50–150 𝛺m. Accordingly, the chemical analysis of water samples collected at these sites also showed relatively low levels of salinity and salt concentrations in them. However, away from the coast, the resistivities vary in the range of 150–1500 𝛺m in the depth range from 20–40 m. While the aquaculture and agriculture activities may contribute to high salinity at the sites closer to the coast, the presence of deep-seated paleochannels aiding in transporting seawater inland, and water–rock interactions are suspected to be the chief causes for notable salinity at places away from the coast at shallow depths. We opine that the high salinity at shallow depths, coupled with the deep-seated paleochannels transporting seawater, could pose problems to probe further depths particularly using electromagnetic induction methods in the study region.

    • Geomorphic settings of mangrove ecosystem in South Andaman Island: A geospatial approach

      E Yuvaraj K Dharanirajan S Jayakumar Saravanan

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      Mangroves are habitats in the coasts of tropics and subtropics, hence the geomorphology of the coast prevails in both the ocean and the land processes. To study the geomorphic setting of mangroves, it is necessary to explore both the topography of the land and the bathymetry of the sea. In this study, the geomorphic setting of mangroves in the South Andaman Island has been studied in detail using remote sensing and GIS technology. The ortho-rectified IRS satellite image was used to identify and to map the mangroves and the associated features using the visual interpretation technique. Using the GIS technique, topographic and bathymetric DEMs (Digital Elevation Models) were created to understand the geomorphology and its influence on the mangrove ecosystem. This DEM was interpreted with mangrove distribution and its associated features to create the DTM (Digital Terrain Model) of the mangrove ecosystem. Topography and bathymetry of the coast result in three dominant features like rivers, tides and waves, which play a role in shaping the geomorphic settings of mangroves, which are classified into five major types. In this study, it is identified that all the five categories of major geomorphic settings of the mangrove community exist in the south Andaman. In the field surveys, ground truth of topographic elevation, mangrove species, and associated coastal land cover features were identified and confirmed in these geomorphic settings. It is concluded that topography and bathymetry settings of the island play an indispensable role in this fragile mangrove ecosystem.

    • A feasibility study on identification of Basmati (aromatic) rice using SAR data

      Varunika Jain C Patnaik S Panigrahy

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      Rice areas in India are being mapped for acreage estimation using Synthetic Aperture Radar (SAR) data under forecasting agricultural output using space, agrometeorology and land-based observations (FASAL) program for over a decade now. Under this study, an attempt was made to segregate rice areas based on variety in parts of Punjab state. Data acquisition was done at critical stages of rice growth. The shift in transplantation in temporal domain and difference in canopy volume formed the basis of characterization of rice crop into two different varieties namely aromatic and non-aromatic. Multitemporal HH polarization data along with rate of change of cross polarization ratio (HH/HV) from July to September 2011 was used. The aromatic rice could be separated from normal rice with 91% accuracy.

    • Mantle source characterization of Sylhet Traps, northeastern India: A petrological and geochemical study

      Md Shofiqul Islam Daniel Meshesha Ryuichi Shinjo

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      In this study, mineralogical, geochemical, and isotopic data are presented for the Sylhet Trap at the southern flank of the eastern Shillong Plateau, northeastern India, to determine the magma genesis in relation to the Kerguelen plume mantle source. Sylhet Trap rocks are porphyritic tholeiite and have diverse chemical compositions from picro-basalt, basalt, andesite to dacite, but mostly are within the subalkaline field. Major and trace element data were used to identify two distinct magma fractionation trends, a low and medium K series, characterized by relatively flat MORB-like (analogous to Rajmahal Traps (II)) and enriched OIB chondrite-normalized Rare Earth Element (REE) patterns. Initial 87Sr/86Sr, 143Nd/144Nd$, and 206Pb/204Pb isotope compositions were widely varied, ranging from 0.70435–0.71357, 0.51196–0.51266, and 17.92–19.72, respectively, when compared with basalts from the West Bengal, the Rajmahal Traps and the Kerguelen plume. Correlations among isotopic and trace element ratios of the Sylhet Traps provide evidence for the involvement of (1) HIMU-like mantle component, (2) the Kerguelen plume-like component, and (3) EMII-like crustal component. Magma from the Sylhet Traps was originated from a melting that derived directly from the heterogeneous Kerguelen mantle plume (components 1 and 2), which strongly suggests the presence of the Kerguelen plume-head in the Bengal basin.

    • Permian ultrafelsic A-type granite from Besar Islands group, Johor, peninsular Malaysia

      Azman A Ghani Fatin Izzani Hazad Azmiah Jamil Quek Long Xiang Wan Nur Atiqah Wan Ismail Sun-Lin Chung Yu-Ming Lai Muhammad Hatta Roselee Nur Islami Kyaw Kyaw Nyein Meor Hakif Amir Hassan Mohd Farid Abu Bakar Mohd Rozi Umor

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      The granitic rocks of the peninsula have traditionally been divided into two provinces, i.e., Western and Eastern provinces, corresponding to S- and I-type granite respectively. The Western Province granite is characterised by megacrystic and coarse-grained biotite, tin-mineralised, continental collision granite, whereas, the Eastern Province granite is bimodal I-type dominated by granodiorite and associated gabbroic of arc type granite. This paper reports the occurrence of an A-type granite from peninsular Malaysia. The rocks occur in the Besar, Tengah, and Hujung islands located in the southeastern part of the peninsula. The granite is highly felsic with SiO2 ranging from 75.70% to 77.90% (differentiation index = 94.2–97.04). It is weakly peraluminous (average ACNK=1.02), has normative hypersthene (0.09–2.19%) and high alkali content (8.32–8.60%). The granites have many A-type characteristics, among them are shallow level of emplacement, high Ga, FeT/MgO and low P, Sr, Ti, CaO and Nb. Calculated zircon saturation temperatures for the Besar magma ranging from 793° to 806°C is consistent with high temperature partial melting of a felsic infracrustal source which is taken as one of the mechanisms to produce A-type magma. The occurrence of the A-type granite can be related to the extensional back arc basin in the Indo-China terrane during the earliest Permian.

    • Palynostratigraphy of Permian succession in the Mand–Raigarh Coalfield, Chhattisgarh, India and phytogeographical provincialism

      Srikanta Murthy Ram-Awatar Saurabh Gautam

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      Palynofloras have been recorded from the Barakar Formation in the Borehole MBKW-3, Barpali–Karmitikra Block, Mand–Raigarh Coalfield, Chhattisgarh. Three distinct palynoassemblages have been identified and referred to the following palynoassemblage zones – Gondisporites raniganjensis (Latest Permian); Faunipollenites varius (latest Early Permian), and Scheuringipollenites barakarensis (late Early Permian). It is inferred that these deposits contain the representative palynoassamblages of Early to Late Permian in age. The First Appearance Datum (FAD)s of Arcuatipollenites pellucidus, A. ovatus, Guttulapollenites hannonicus, Lundbladispora microconata, Alisporites opii, Klausipollenites sp., and Goubinispora indica (at 41.95, 45.90, 98.35 m depths), indicate the closing phase of Permian, as these elements are the key species that mark a transition from Permian to the Lower Triassic. An attempt has been made here to reconstruct the phytogeographical provincialism on the basis of Guttulapollenites recorded in this basin.

    • Palynostratigraphy of Permian succession from Binja Block, South Karanpura Coalfield, Jharkhand, India

      Srikanta Murthy Archana Tripathi B Chakraborti U P Singh

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      Palynological investigations are carried out on approximately 538.00-m thick Gondwana strata from borehole SKB-1, Binja Block, South Karanpura Coalfield in Jharkhand. Based on the distribution pattern of age marker palynotaxa, two distinct palynoassemblages are identified. Palynoassemblage-I in the lithologically designated Barren Measures and Barakar formations, between 552.00 and 53.20 m depth show dominance of striate bisaccate (Striatopodocarpites, Crescentipollenites, and Faunipollenites) and abundance of nonstriate bisaccate (Scheuringipollenites). Upward the Palynoassemblage-II (39.50–13.80 m depth) is rich in striate bisaccate (Striatopodocarpites and Crescentipollenites) and significant enveloping monosaccate Densipollenites magnicorpus pollen. These strata have been equated with Raniganj Formation of Latest Permian age. The First Appearance Datum (FAD) of Arcuatipollenites pellucidus, Playfordiaspora cancellosa, Alisporites sp., Falcisporites sp. and Krempipollenites indicus observed at 13.80 and 39.50 m depth, mark the transition of Permian into the Lower Triassic. The FADs of Guttulapollenites spp. at 49.10 and 504.70 m, Goubinispora morondavensis at 415.90 m, Alisporites ovalis and Arcuatipollenites sp. at 526.70 m is observed and suggest that these sediments are equivalent to Raniganj Formation, Late Permian in age.

    • Geoelectric structure estimated from magnetotelluric data from the Uttarakhand Himalaya, India

      Rohit Miglani M Shahrukh M Israil Pravin K Gupta S K Varshney Sokolova Elena

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      Geoelectric strike and resistivity structure of the crust have been estimated from 37 magnetotelluric (MT) data sites along a profile from Roorkee to Gangotri in Uttarakhand Himalaya. Impedance decomposition schemes based on Bahr’s, Groom Bailey and Phase tensor were implemented in a MATLAB code for the average strike estimation. Geoelectric strike direction varies with period as well as in different lithotectonic units along the profile. In the period band from 1 to 100 s average geoelectric strike in the southern end of the profile (Indo-Gangetic Plains) is N79°W, which is slightly rotated to the north in the Lesser Himalayan region and becomes N68°W whereas it is N81°W in the Higher Himalayan region. However, average strike is stabilized to N77°W for the entire profile in the long period band (100–1000 s). Geoelectrical structure of the crust has been obtained along the profile by 2D inversion of MT data. Major features of 2D resistivity model are: (i) southern part of the model is a low resistivity (> 50 𝛺m) zone at shallow depth (5–7 km) representing the loose sediments of the Indo-Gangetic Plains (IGP), whose thickness increases in the south; (ii) highly resistive (>1000 𝛺m) layer below the IGP sediments is the basement rock, representing the resistivity of the top of the subducting Indian Plate; (iii) the Main Boundary Thrust (MBT) and the Main Central Thrust (MCT) zones can be seen in the electrical image. However, the Himalayan Frontal Thrust (HFT) could not be resolved and (iv) a low resistivity (> 10 𝛺m) feature in the MCT zone extending to the depth of 30 km is delineated. This low resistivity could be due to fluid-filled fractured rock matrix or partial melt zone. Hypocenters of many earthquakes are concentrated along the boundary of this low resistivity zone and relatively high resistivity blocks around it. The resulted model supports flat-ramp-flat geometry of the Main Himalayan Thrust along which the Indian Plate is subducting.

    • A new PPP algorithm for deformation monitoring with single-frequency receiver

      Yanli Zheng Rui Zhang Shengfeng Gu

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      Considering the applications of deformation monitoring, PPP (precise point positioning) with singlefrequency (SF) receivers has the advantages of stand-alone, absolute positioning and cost efficiency. However, the existing SF PPP methods can be hardly implemented for deformation monitoring directly due to their limited precision of submeter level. For this purpose, an innovative approach is presented in this paper with several improvements to the existing approaches: firstly, the SEID (Satellite-specific Epoch-differenced Ionospheric Delay) model is adopted in SF kinematic PPP to handle the ionospheric delays for SF receivers embedded in networks of dual-frequency (DF) receivers; secondly, according to the dynamic characteristic of the monitor station, a combination of kinematic PPP and sliding window based static PPP algorithm is adopted. To confirm the availability of the algorithm for deformation monitoring with SF receiver, a seismic experiment is carried out on an earthquake simulation platform. Comparable positioning precision with 1.5 cm for horizontal and 2.2 cm for vertical is achieved by SF PPP with respect to RTK (real-time kinematic) solution. The new deformation monitoring algorithm with SF receiver can be treated as an effective and low cost way to realize some types of geological hazard monitoring in a wide range.

    • Subject Index

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    • Author Index

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    • Acknowledgements

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