Abstract The tropical Indian Ocean is a net sink for the carbon dioxide (CO2) in the atmosphere and phytoplankton production plays a crucial role in CO2 fixation and determines the direction of CO2 flux at the sea-to-air interface. In order to assess the influence of phytoplankton composition and primary production on pCO2 levels in the Indian Ocean, sampling was conducted at 25 stations during the

Geological and geochemical characteristics of the litho units exposed in and around Kalalikhera area of Pur-Banera belt have confirmed the presence of felsic volcanic rock unit named Kalalikhera felsic volcanic, with characteristic features such as (i) abundance of lapilli composed of polygonal quartz and feldspar and (ii) presence of relict bipyramidal quartz. These volcanics are associated with thin

Abstract Gas hydrates from the continental margin settings are mostly confined to continental slopes. The free gas occurring below the gas hydrate laden sediments play a crucial role in the submarine slope failures and can potentially trigger the submarine landslides. The present study is carried out to investigate such a scenario in the shale dominated Krishna–Godavari (KG) basin having proven gas

Prediction of heavy/extreme rains is still a challenge, even for the most advanced state-of-the-art high-resolution Numerical Weather Prediction (NWP) modelling systems. Hydrological models use the rainfall forecasts from the NWP models as input. This study evaluates the performance of the UK Met Office Unified Model (UM) in predicting the rainfall exceeding 80th and 90th percentiles. Such high rainfall

Snow/ice cover is an integral part of the Earth’s climate system. Earth’s snow/ice cover helps regulate the energy exchange between the Earth’s surface and the atmosphere, directly regulating the surface (and near-surface) temperatures. This study utilizes measurements from the Moderate Resolution Imaging Spectroradiometer (MODIS) MCD43C3 dataset to derive the albedo and snow cover variation over the

Groundwater recharge is a hydrological process where water flows from sub-surface layers to the water table of the aquifer and is the backbone of the hydrogeological system. The present study is carried out in a granitic hard rock aquifer region within and surroundings of the CSIR-NGRI campus, Hyderabad. The aim of this study to identify the potential groundwater recharge zone(s) using GIS based multi-criteria

The Delhi Seismic Zone (DSZ) is a seismically highly active intraplate region that keeps experiencing recurrent seismicity of minor to moderate nature. The seismic activity in the DSZ in recent times has evoked concerns about the vulnerability of the region due to potential earthquakes. Although the spatial distribution of recorded earthquakes gives a fairly good idea about the zone of the seismicity

Abstract We describe the variability of the West India Coastal Current (WICC) during 2009–2017 using data from acoustic Doppler current profilers (ADCPs) attached to moorings deployed on the outer shelf at a water-column depth of 100–200 m at three locations: off Kollam (9°N), Bhatkal (13.9°N), and Goa (15°N). Our study shows that the characteristics of the WICC on the outer shelf are similar to those

A short-lived flashflood in Rishi and Dhauli Ganga rivers on 7th February 2021, Uttarakhand Himalaya, killed 65 people with 141 reported missing (official estimate) and devastated two hydropower projects. Geomorphological observations supported by meteorological data suggest that the flood was triggered by a combination of avalanche and debris flow. The Dhauli Ganga valley has preserved ponded sedimentary

We report microtektites recovered from a large area of the deep seafloor (Central Indian Ocean) that appear to have undergone aerodynamic distortion during re-entry into the atmosphere. Considering the geographic locations, stratigraphic position and chemical compositions these glassy forms belong to the Australasian tektite strewn field. The microtektites are elongated to lengths of cms, sometimes

Abstract Deep-sea moorings in the equatorial Indian Ocean were first deployed by India in the year 2000, and currents were measured at three locations (\(77^\circ \hbox {E}\), \(83^\circ \hbox {E}\), and \(93^\circ \hbox {E}\)) on the equator. In this paper, we present two decades of current observations from these moorings and discuss how the moorings have evolved with time. The observations show

Abstract Malani Igneous Suite represents the largest felsic volcanic province in India. Despite a number of studies, the origin and the temporal extent of the Malani magmatism remain elusive. Adjacent to the Malani Igneous Suite, there exists a calcareous felsic tuff deposit at Chhoti Khatu within the younger Marwar Supergroup. It is stratigraphically separated from the Malani Igneous Suite by the

Abstract An automatic 3D spatial domain inversion technique is developed to estimate basement depths of sedimentary basins from observed gravity anomalies using a prescribed exponential mass density contrast. A collage of vertical polygonal cross-sections, each one with unit thickness, in which the density contrast differs exponentially with depth describes the model space. The proposed technique estimates

Abstract Rip currents are known as one of the most dangerous hazards on sandy beaches worldwide. Indian beaches are least explored to study the variability of rip currents in space and time. The present study is the first attempt made to understand its dynamics by utilizing indigenously developed GNSS (Global Navigation Satellite System) drifters and Rhodamine-B dye experiments. The Rama Krishna (RK)

Abstract Thunderstorms, associated with lightning and heavy rain, are a weather hazard causing human deaths, urban floods and damage to crops. Current work attempted to study the thunderstorms over Andhra Pradesh, coastal state in southeast India, using multiple satellite datasets, gridded rainfall, Doppler Radar Images and Advanced Research Weather Research and Forecasting (ARW) model simulations

Due to an oversight, figure 3 (Article ID 25) of the article was published with an incorrect figure.

Abstract Landslides are global natural hazards with significant social and economic impact. The study is conducted in the wake of landslide occurrences in Kerala state, India, during 2018–2019. This study aims to demarcate landslide hotspots in the study area, identify anthropogenic activities, and critically examine their role in landslide occurrences. The identified landslide hotspots are utilized

Abstract Simulating upper layer of Bay of Bengal through three-dimensional ocean circulation models is a challenging task. In this study, the surface current from the Nucleus European Modelling of Ocean (NEMO) based global ocean assimilation system is assessed against the high frequency (HF) radar data along the Andhra Pradesh coast on a daily scale during southwest monsoon 2016. The temporal variation

Abstract The southern peninsular India is characterized by unique climatology with rainfall processes throughout the year from land–ocean contrasts. In addition, the complex terrain induces localized effects causing huge spatial and temporal variability in the observed precipitation. This study aims at evaluating the sensitivity of the high-resolution Weather Research and Forecasting (WRF) model (4

Abstract India experienced two extreme summer monsoons, 2007 (active monsoon) and 2009 (weak monsoon) in the recent past decade. The characteristic features of these two contrasting Indian summer monsoons have been presented. The country received 11.8% excess and 17.1% deficit rainfall during 2007 and 2009 monsoon seasons, respectively. These large deviations in rainfall encourage us to study the influence

Abstract Larger benthic foraminifera (LBF) contribute significantly to the modern reef carbonates. They were also the major producers of carbonate in the shallow marine environments of the Paleogene. It is thus imperative to investigate their potential as a paleotemperature proxy. It is common to calculate past seawater temperatures using trace elements and stable isotope proxies on foraminiferal calcite

Abstract An assessment of wind energy potential based on wind speed data over the Indian subcontinent has been made using high spatio-temporal resolution global reanalysis for the period from 1979 to 2018. Regions of high wind speed exceeding 4.5 m/s are identified over West Rajasthan, West Gujarat, Saurashtra and Kutch, Central Maharashtra, Interior Karnataka, and Rayalaseema. Threshold wind speeds

A ~125 m thick shallowing-upward arenaceous succession from the Badalgarh Formation, Bayana basin, India provided the opportunity to document shelf to foreshore transition from a paleoproterozoic rift set-up. Process-based facies analysis allowed identification of 12 different shallow-marine facies types, grouped under four different facies associations namely (i) lower offshore or open shelf, (ii)

Research highlights The clay fraction of the sediments in 15 rivers along the east coast of India showed Mixed-mineral assemblages in accordance with dominant geology and chemical weathering. High CIA and PIA, and low Ca, K, Na and Sr values indicating moderate to intense chemical weathering on source rocks. Enriched transition metals and depleted high-field strength elements supporting dominance of

Abstract Porosity is a key parameter for reservoir evaluation. Inferring the porosity from seismic data is often challenging and prone to uncertainties due to number of factors. The main aim of this paper is to show the applicability of seismic inversion on old vintage seismic data to map spatial porosity at reservoir level. 3D-seismic and wireline log data are used to map the reservoir properties

Abstract For understanding the sediment removal mechanism from the bank face, field measurements of the dominating turbulent flow structures under the influence of flood and ebb tide were carried out at the middle reach 98 km upstream of the mouth of Rupnarayan River, India where the bank erosion activity was highly dynamic. Measurement of the three-dimensional temporal variation of velocity was carried

Abstract Here the depositional environment and hydrocarbon source rock potential of the Kopili Formation is investigated using palynological analysis and Rock-Eval pyrolysis on samples from a borehole section (Borehole BUM14) collected at Umphyrluh area in the Jaintia Hills, Meghalaya. In these Kopili shales, amorphous organic matter is often associated with structural terrestrial organic matter, biodegraded

Abstract Spectral characteristics of nine coral species (Acropora Nobilis, Acropora Hyacinthus, Acropora Varibalis, Favia Speciosa, Favia Stelligera, Porites Lobdata, Porites sp., Pocillopora Domicornis and branched dead corals), two seagrass species (Zosteraceae and Posidoniaceae), two sand benthic communities (sand mixed with coral rubble and carbonate sand), reef vegetation and sea moss were recorded

Gassendi impact crater is located on the western side of the visible lunar hemisphere just north of Mare Humorum. It has a diameter of 110 km, and it is a Floor Fractured Crater (FFC) belonging to Class-3 type that exhibits a wide annular depression or moat. Is Gassendi crater formed due to igneous intrusion or viscous relaxation? To investigate this, the analysis explores the compositional and morphological

Abstract A large extent of brackishwater resources is yet to be used for aquaculture as the present development stands at only 13% in India. But, growing environmental concerns and crop failures have made site selection a mandatory requirement for cage aquaculture. The case study carried out at Muttukadu Lagoon, India, has used 13 factors to assess cage site suitability, including physical characteristics

Abstract In this study, we have assessed the skill of decadal prediction of boreal spring (March–May) and summer (June–September) Surface Air Temperature (SAT) over India and its relation with Sea Surface Temperature (SST) in the National Centers for Environmental Prediction (NCEP) Climate Forecast System Version 2 (CFSv2) coupled model. The skill of CFSv2 is compared with CNRM (Centre National de

Abstract The major objective of any national weather forecasting services is to provide weather forecast and warnings and other meteorological related information to the public and government for the safety of life and property and economic activities. The heavy rainfall causes huge loss to the public in form of flood and landslide in varying severity mainly during monsoon season (June–September).

Abstract The use of interpolated digital elevation models (DEM) obtained from free low-resolution satellite images is a typical solution for soil erosion modelling. However, this method may result in loss of surface details, especially in small catchments. Thus, planialtimetric surveys at the study site may improve quality of terrain description, although it requires high costs and time. Therefore

Abstract On January 26, 2020, a moderate-sized earthquake (ML ~ 4.6) located in the Palnadu sub-basin of Cuddapah basin was felt both in the states of Telangana and Andhra Pradesh. The earthquakes prior and after the ML 4.6 are located close to the thrust and along the periphery of the backwaters of the Pulichintala Reservoir. About 965 earthquakes in the magnitude range of 0.1–4.6 ML have been located

The study of the Earth's topographic surface using digital topography is an important component of many problems in the Earth Sciences. The 30-m Shuttle Radar Topography Mission (SRTM) and the Advanced Land Observing Satellite (ALOS) global digital topography datasets have been the most recently available global digital topography datasets. Most users directly download the data/DEMs in their native

Research highlights Field based temperature lapse rate, precipitation gradient and snow melt factor established for the Patsio glacier. Seasonal sensitivity of the glacier mass balance was studied. Past reconstruction of the glacier mass balance using bias corrected ERA5 reanalysis. Comparison of modeled mass balance with published geodetic and glaciological results. Abstract Comprehensive assessment

Abstract The iron oxide concretions of Shankargarh (Allahabad), India belongs to Dhandraul Sandstone of Vindhyan Supergroup. Petrography of concretions shows abundant quartz grains embedded within the iron oxide cementation. XRD analysis of the concretion shows diagnostic peaks for quartz, hematite, and goethite. The A–CN–K and A–CNK–FM ternary diagrams drawn for concretion and host rock bulk composition

Abstract The Chilika Lagoon is the largest brackish water ecosystem in the Asian continent and is a Ramsar site. Here, the sorption–desorption study was standardized simulating the environmental condition of the Chilika, to ascertain whether phosphorus (P) is the source or sink for sediments of the coastal ecosystem. The sorption behaviour of sediment phosphorus was better fitting into the modified

Highlights Monthly S2S reforecast for 20 years obtained from the European Centre for Medium-Range Weather Forecast (ECMWF) were evaluated against the in-situ rainfall data over Zambia using 1-month lead time forecast. The two datasets agree with the rainfall pattern throughout the year thereby, the S2S ECMWF realistically simulates the mean annual cycle skillfully by identifying the wet season from

Research highlights Sensitivity of initial and boundary conditions (ICs) are studied for an extra-tropical cyclone (ETC, Gong (2013)) over North Atlantic Ocean using WRF model. Movement (track) and synoptic feature of Gong have been evaluated with observations. WRF could simulate the characteristics throughout life cycle of Gong. The model attained intense stage was well simulated. Cyclogenesis and

Abstract The estimation of a reliable velocity–depth model from towed streamer marine seismic data recorded in deep water, especially with a complex seafloor environment, is challenging. The determination of interval velocities from the normal move-out (NMO) of the reflected seismic signals for shallow reflectors (<1 km below the seafloor) is compromised by the combination of a long wave path in the

Abstract The Siang antiform which forms the southern portion of the Eastern Himalayan Syntaxis is a massive subaerial duplex comprised of Paleogene rocks. The specifics of growth and deformation of the Siang duplex remain ambiguous due to limited studies in the region. Using multi-thermochronometry and Raman spectroscopy of carbonaceous matter (RSCM), this study place temporal depth constraints on

Abstract A ~60 km long Veldurti–Kalva–Gani (VKG) fault is one of the identified strike-slip faults extending from Eastern Dharwar Craton (EDC) to Cuddapah basin in South Indian Shield. The recorded recent seismic activity during year 2012–2016 show occurrences of three microseismic events (< Mw 2.0) in the vicinity of this fault. Historically, no major seismic events are recorded near this fault except

Abstract Association of higher (lower) rainfall with lower (higher) Aerosol Optical Depth (AOD) is consistent with the understanding that increased washout (build-up) and shorter (longer) life-time of aerosols occur in wetter (drier) conditions. Given the life-time of aerosols, it is imperative to examine how aerosols impact active/break (wetter/drier than normal) spells, prominent intraseasonal variability

Abstract Water vapour is highly variable over tropical region and sensitive to weather condition, monsoon onset, green house effect, and pollution level in Ganga River. In the present study, variability in water vapour derived from Global Positioning System (GPS) over Varanasi (25°20′N, 82°59′E) during the period 2007–2010 has been studied. The GPS-derived water vapour (WV) has been compared with those

Research highlights The earthquake catalogue of Himalaya between 1225 and 2017 is compiled. The active tectonic front of the Himalaya is subdivided into 14 zones (1–14) between MFT and MCT. The moment ratio < 1 in 10 zones [1 (Kashmir), 3 (Kangra), 5 (Almora), 6 (Central-gap1), 8 (Pokhra–Kathmandu), 9 (Everest), 11 (W Bhutan), 12 (E Bhutan), 13 (Arunachal) and 14 (Eastern Syntaxis)], show good agreement

Abstract In this study, wavelet transform (W), which is one of the data pre-processing techniques, adaptive neural-based fuzzy inference system (ANFIS), support vector machine (SVM) and artificial neural networks (ANNs) were used to develop the drought estimation models of Çanakkale, Turkey. For these models, 3-, 6-, 9- and 12-months drought indices were calculated by standard precipitation index (SPI)

Abstract Indian National Satellite System (INSAT) multi-spectral Rainfall Algorithm (IMSRA) is an operational rainfall estimation technique of INSAT-3D at Indian Meteorological Department (IMD) and Meteorological and Oceanographic Satellite Data Archival Centre (MOSDAC) since 2014. The IMSRA rain estimates are widely used for various application studies. This algorithm is based on an empirical power-law

Abstract Two alternative petrogenetic models, plagioclase flotation and serial magmatism have been proposed to explain the origin of the lunar anorthositic crust, covering ~80% of the lunar highland. In this study, we re-examine the possible relict igneous texture present in an inferred lunar highland breccia clast (area ~1 mm2) in the Dhofar 081 meteorite. Our new petrographic and in-situ mineral

Abstract In this paper, the computation of seismic responses of complex ridge topography is documented that can provide a reliable scenario of ridge amplification. This research work is inspired by the topography of the great Himalaya, wherein the increase of height from the south to north is in form of ups (anticlines) and downs (synclines). The viscoelastic SH- and SV-wave responses of triangular

Abstract Accurate surface runoff prediction is vital for water resources engineers for various applications. Advances in the artificial intelligence techniques can act as robust tools for modelling hydrological processes. The present study focuses on testing the reliability of different data sources and choosing the correct source to model the rainfall-runoff process under data scarce situations using

Abstract An objective wavelet based algorithm has been developed to find the orientation of rolls in Synthetic Aperture Radar (SAR) imagery using Radar Imaging Satellite (RISAT-1) data. The orientation of rolls plays a very crucial role for the estimation of ocean surface wind direction. It also affects the shape and size of a tropical cyclone. In this manuscript, SAR image was decomposed using Haar

Abstract Uttarakhand, a hill state of India, covers an area of 51,125 km2. The geographic position is highly crucial with in the Central Himalayas (CH), for agro-climate, water resource management, food-processing, tourism, etc., having enriched bio-diversity and forest. Present study investigates the spatio-temporal characteristics and distribution of temperature of Uttarakhand state. Observation

Abstract Sadrabadi and Zilphi villages of Dharni Taluka in Amravati district, Maharashtra, experienced small magnitude earthquakes between September 1, 2018 and December 9, 2018. We deployed a four station temporary network of three component broadband seismographs to understand and characterize the earthquake sequence. We find that the short lived (~2 months) micro-earthquake (M ≤ 2.4) swarm, accompanying

Abstract Open cast coal mine (OCCM) may impose adverse effects on groundwater quality and on its flow regime. Evaluation of water quality often becomes difficult and confusing due to presence of multiple criteria and index based on different parameters. A novel approach has been introduced which speaks about a single index revealing the effect of all important parameters to determine the quality for

Abstract The Greater Himalayan Sequence (GHS), constituting the anatectic core of the Himalaya, is generally modelled as a mid-crustal southward extruding channel or wedge. Movements along the Main Central Thrust (MCT) in the south and the South Tibetan Detachment System (STDS) in the north and exhumation along the Himalayan front played an important role in the extrusion of the GHS from beneath the

Abstract The Koraiyar River basin is located in Tiruchirappalli city, one of the fastest-growing medium-sized cities in south India. Over the decades, the city has experienced sporadic flooding in vast areas due to the breaching of bunds when the river is in spate. The objective of this investigative study is to simulate rainfall–runoff in the Koraiyar basin watershed through the reliable Hydrologic

Abstract The microfacies of Pleistocene calcareous crust in Tunisia revealed the presence of diverse aspects of acicular crystallizations in a porous system. These crystallizations are in the shape of branched filaments, mono or polycrystalline rods which are either smooth or serrated (calcite), and serrated edge needle (calcium oxalate). The genesis of these acicular structures seems to be directly

P wave tomographic imaging of the crust down to a depth of 90 km is performed beneath the region encompassing Sumatra, Java, Malacca Strait, peninsular Malaysia and Singapore. Inversion is performed with 99,741 first-arrival p waves from 16,196 local and regional earthquakes occurred around the Sumatra Subduction Zone (SSZ) between 1964 and 2018. Tomographic results show low-velocity (low-V) anomalies

Gravity Recovery and Climate Experiment (GRACE) data are a valuable source of information for estimating hydrological mass changes. Several approaches have been conducted to investigate surface density changes from satellite-based observations. The traditional approaches are mainly based on the Stokes coefficients, related to a spherical harmonic representation of the gravitational potential. This