Showing papers in "Current Science in 2019"

Role of dams on the floods of August 2018 in Periyar River Basin, Kerala

Abstract: Kerala state (India) experienced a devastating flood event during the month of August 2018. While an extreme rainfall event (ERE) was the primary reason for this flood, there was criticism at various levels that the authorities failed to manage the flood effectively through reservoir operations. One of the worst affected basins, Periyar River Basin (PRB), received a 145 year return period rainfall. This study reports the results and analysis of a modelling exercise using HEC-HMS to simulate and analyse the role of dams, as well as reservoir operations, on the flood of August 2018. The results indicated that the role of releases from the major reservoirs in the PRB resulting in the flood havoc was less. The analysis suggested that reservoir operations could not have helped in avoiding the flood situation as only 16–21% peak attenuation was possible by emptying the reservoir in advance, as the bulk of runoff to the flooding was also contributed by the intermediate catchments without any reservoirs to control. Further, the attenuated flood peak due to advance emptying of the reservoir would still be almost double the safe carrying capacity of the river section at Neeleswaram. In addition, the reliability of the rainfall forecast at higher lead times is also a concern for the reservoir operation. It is noted that the probability of EREs of this kind in the month of August in PRB is very small (0.6%), and therefore any planned operation could not have helped in mitigating floods of such magnitude without a reliable EREs forecast coupled with reservoir inflow forecasting system and optimized set of reservoir operational policies.

On the Recent Floods in India

Abstract: Floods in the Indian subcontinent have affected habitat, population, economy, etc. Due to the detrimental effects of recent floods on the economy, governance, etc., it is imperative to understand the associated dynamics, manifestations and fallouts for proper policy planning recommendations. The present study endeavours to provide an integrated rationale of meteorological and geomorphological aspects associated with four recent extreme floods in Uttarakhand (2013), Srinagar (2014), Chennai (2015) and Gujarat (2017). It is important to mention here that these floods occurred under different atmospheric circulations and geomorphological setting, and had an entirely different gambit for policy planning and governance. Consolidation of these issues will help policy planners and technologists, in case advance warning system based on these findings can be developed.

An Overview of AVIRIS-NG Airborne Hyperspectral Science Campaign Over India

Abstract: Bimal K. Bhattacharya*, Robert O. Green, Sadasiva Rao, M. Saxena, Shweta Sharma, K. Ajay Kumar, P. Srinivasulu, Shashikant Sharma, D. Dhar, S. Bandyopadhyay, Shantanu Bhatwadekar and Raj Kumar Space Applications Centre, Indian Space Research Organisation, Ahmedabad 380 015, India Jet Propulsion Laboratory, California Institute of Technology, CA 91109, USA National Remote Sensing Centre, Indian Space Research Organisation, Hyderabad 500 625, India Earth Observation Science Directorate, Indian Space Research Organisation, Bengaluru 560 231, India

Comparison between Scopus, Web of Science, PubMed and publishers for mislabelled review papers

Abstract: The present study examined the incidence rate of re-views being mislabelled by Scopus, and compared this rate with Web of Science (WoS), PubMed and official websites of publishers. Top 400 cited publications de-fined by Scopus as ‘articles’ were examined. Their contents were evaluated to see if any were actually reviews. These publications were cross-checked in WoS, PubMed and publisher websites to identify the assigned document type labels. Out of the 400 Scopus ‘articles’, 117 were reviews (29.3%). The official web-sites of publishers had 16.0% incidence of mislabelled reviews, which was less than Scopus (29.3%) but more than WoS (14.1%) and PubMed (1.9%).

Aerobic Granular Sludge:The Future of Wastewater Treatment

Abstract: Water, food and energy security are interlinked and central to sustainable development. Wastewater is a key element in the water–food–energy nexus, and recovery of resources can link water, nutrient and energy cycles. Effective treatment of wastewater is essential for public health and sanitation, water reclamation, preventing environmental pollution and protecting water resources. Furthermore, the treated wastewater is a potential resource and its reuse will partially offset supply and demand in water-stressed areas. A century-old activated sludge (AS) process is still widely employed, though not sustainable in terms of large land footprint, higher costs and complex designs for achieving biological nutrient removal. The recently developed aerobic granular sludge (GS) process is a better replacement for AS and promises sustainable wastewater treatment for at least the next century. The GS process uses familiar sequencing batch reactor technology for simultaneous removal of organic carbon, nitrogen, phosphorus and other pollutants from wastewater. Among the available biological treatment options, GS process is the most preferred choice because of smaller land footprint, lower costs and effective wastewater treatment. Accumulating research shows that the GS technology has gained enormous popularity; it is increasingly considered for capacity extension as well as new wastewater treatment plants in domestic and industrial sectors.

Landslides Mapped using Satellite Data in the Western Ghats of India After Excess Rainfall During August 2018

Abstract: Excess rainfall during August 2018 triggered numerous landslides in the Western Ghats region of India covering the states of Kerala, Karnataka and Tamil Nadu. These landslides caused widespread damage to property, loss of life and adversely affected various land resources. In this article, we present an inventory of landslide prepared from the analysis of multitemporal high-resolution images acquired before and after the rainfall event from Resourcesat-2, WorldView-2, GF-2, SPOT-6 and 7, Pleiades-1, Kompsat-3 and Sentinel-2 Earth observation satellites. A total of 6970 landslides with a cumulative area of 22.6 sq. km were mapped for this rainfall event. Majority of landslides have occurred in Kerala (5191), followed by Karnataka (993) and Tamil Nadu (606). Landslides are mostly debris slide and debris flow type with entrainment along the channels. Results show that landslides (83.2%) are triggered by very high rainfall. Also, very high rainfall has resulted in 14.9% of landslides even though slopes are moderate, mainly in the Kodagu district of Karnataka.

Fate and Transport of Microplastics from Water Sources

Abstract: Microplastics as environmental pollutants affect surface water and groundwater. Surface water, groundwater and branded drinking water bottles were analysed in and around Chennai, Tamil Nadu, India. The total count of microplastics was found to be 66 particles with fibrous and fragmented shape, colours such as white, blue, green, yellow, pink and black under optical microscope. SEM-EDX-used to study morphology and elemental analysis of microplastics confirmed the presence of heavy metals such as Cr, Ti, Mo, Ba and Ru adhered to their surface. Polyethylene terephthalate and polyamide were confirmed by the presence of functional groups of the polymers by FTIR equipped with attenuated total reflectance.

Water resources management in India –challenges and the way forward

Abstract: Management of water resources in India has been a challenge whose magnitude has risen manifolds over the past 50 years due to a variety of reasons, notably the rising demands and growing environmental degradation. Broadly, most of the challenges in water management in India can be categorized in the following groups: (a) water availability, variability and increasing withdrawals, (b) environment and quality, (c) project construction, (d) water sharing disputes, (e) water governance and institutions, and (f) challenges induced due to climate and land-use cover changes. Here we discuss each of these challenges in detail. It is suggested that conservation of water and management of variabilities should be a cornerstone of water resources management in India. This note also suggests remedies to address the challenges and covers new initiatives by the Government of India (GoI).

SCATSAT-1 Scatterometer:An Improved Successor of OSCAT

Abstract: SCATSAT-1 is the Indian Space Research Organisation’s (ISRO’s) newest Ku-band scatterometer which was launched on 26 September 2016 from ISRO’s space-port Sriharikota on-board the PSLV C35 mission. It is an advanced follow-on of OSCAT, ISRO’s first Scatterometer in space on-board the Oceansat-2 satellite, which ceased to operate in April 2014. OSCAT had been a globally acclaimed sensor during its lifetime. The data from SCATSAT-1 exhibit superior quality, and will not only serve the operational wind and weather prediction community in the years to come, but also hold the promise of securing a place in the long-term climate data records. SCATSAT-1 is a standalone scatterometer mission atop the Indian Mini Satellite (IMS-2) bus. The scatterometer payload is a two-beam, dual-polarized, conically scanning, pencil beam, real-aperture radar which measures near-surface wind vectors over ocean exploiting Bragg scattering resonance at Ku-band. It has been developed in ISRO’s Space Applications Centre, Ahmedabad in less than two and half years to replace OSCAT. Although it inherits the instrument specifications from OSCAT, several enhancements have been made in its hardware as well as in the payload characterization from the purview of miniaturization and performance improvement over OSCAT. This article highlights the hardware improvements, the payload characterization methods devised, and the performance enhancements of SCATSAT-1 over OSCAT. The in-orbit performance of SCATSAT-1 is also discussed.

Impact of Salinity and Zinc Application on Growth, Physiological and Yield Traits in Wheat

Abstract: Globally salinity impairs the productivity potential of agricultural land. Apart from salinity, there are a number of factors responsible for the stagnation of wheat productivity. This problem is becoming acute day by day due to improper management of natural resources. Salinity has repressive effects on physiological characteristics of wheat. Soil salinity affects plant growth by creating water and ionic imbalance in the plant due to the presence of toxic ions. Salt-affected plants exhibit stunted growth and have darker leaf colour. Nutrient deficiency is another yield-limiting factor and this problem is aggravating gradually due to intensive cultivation, imbalanced and injudicious usage of fertilizers. The widespread deficiency of nitrogen and phosphorus is followed by Zn deficiency. Zinc is an important component of proteins and acts as a structural, functional or regulatory cofactor of a number of enzymes. Moreover, it plays a significant role in plant metabolism. Generally, the presence of excess salt decreases photosynthesis, total carbohydrate, fatty acid and protein, therefore, zinc has the tendency to offset the negative effects of salinity on plant growth.

India’s Evergreen Revolution in Cereals

Abstract: The term ‘Green Revolution’ (GR) is used to highlight an unprecedented increase in wheat production in India during 1968–72. The critics of GR allege that there is technology fatigue, especially after 1980s. The present study was undertaken to analyse the trends in productivity of major cereals and compare yield gains during the GR era and post-GR era. The period of 68 years since 1950 was divided in four phases: pre-GR era (1950–66) referred to as phase I, GR era (1967–83) as phase II, post-GR era of 1984–2000 as phase III and post-GR era of 2001–17 as phase IV. The annual rate of gain in productivity (kg/ha/yr) in each phase was estimated by linear regression. The annual gain in wheat productivity in phase III (53.1 kg/ha) was 30% higher than that in the GR era (41.0 kg/ha). In rice, the productivity gains increased consistently: annual gain in phase III (32.3 kg/ha) and phase IV (41.6 kg/ha) was 68% to 117% respectively, higher than that in the GR era (19.2 kg/ha). The rate of gain in productivity of maize and pearl millet in phases III and IV was 188–530% higher in comparison to the GR phase. The progress can largely be attributed to development and adoption of improved cultivars with higher yield potential and crop management technologies. The analysis provided conclusive evidence of India experiencing evergreen revolution in major cereals.

SCATSAT-1 Wind Products for Tropical Cyclone Monitoring, Prediction and Surface Wind Structure Analysis

Abstract: The present study discusses the application of near real-time ocean surface wind vectors retrieved from scatterometer instrument, on-board Indian polar satellite SCATSAT-1, for tropical cyclone (TC) analysis and prediction. The real-time tropical cyclogenesis prediction of cyclonic activities in the North Indian Ocean basin has been presented using SCATSAT-1 wind data. The study also demonstrates the utility of high-resolution surface wind products of the scatterometer in monitoring mesoscale-level features of TCs for centre determination, size estimation and analysis of asymmetric wind radii. Impact of SCATSAT-1 winds for TC prediction using numerical weather prediction model has also been discussed. The shortcomings of ocean surface wind observations from space-based scatterometers are addressed, in addition to the sensor requirements for future satellite missions.

Mangrove Species Discrimination and Health Assessment using AVIRIS-NG Hyperspectral Data

Abstract: Mangroves play a major role in supporting biodiversity, providing economic and ecological security to the coastal communities, mitigating the effects of climate change and global warming. Species level classification of mangrove forest, understanding physical as well as chemical properties of mangrove vegetation, mangrove health, pigments, and levels of stress are some of the key issues for making scientific and management decisions. Hyperspectral remote sensing owing to its narrow bands, yield information on structural details and canopy parameters. Hyperspectral data over Sundarban and Bhitarkanika mangrove forests are analyzed for species discrimination and forest health assessment. In all, 15 mangrove species in Sundarban and 7 mangrove species in Bhitarkanika have been identified and classified using Spectral Angle Mapper technique. In-situ spectro-radiometer data has been used along with AVIRIS-NG hyperspectral data. Based on response of vegetation in blue, red and near-infrared regions, combination of vegetation indices are used to assess mangrove forest’s health. Reduction in NIR reflectance with shift towards lower wavelength has been observed in less healthy groups.

Retrieval of Atmospheric Parameters and Data-Processing Algorithms forAVIRIS-NG Indian Campaign Data

Abstract: Applications of high-spatial resolution imaging spectrometer data acquired from the Airborne Visible/ Infrared Imaging Spectrometer-Next Generation (AVIRIS-NG) under India campaign 2015–16, require a thorough compensation for atmospheric absorption and scattering. The data-processing algorithms used for retrieving critically important atmospheric parameters, namely ‘water vapour and aerosol optical depth (AOD)’ over land and water surfaces are presented. Over land surfaces, the dark dense vegetation method and radiative transfer modelling are used for deriving spectral AOD for boxes of 20 × 20 pixels. For AOD retrieval over water surfaces, dark-target approximation is used with near-infrared and shortwave infrared measurements. Estimation of precipitable water vapour is carried out using short-wave hyperspectral measurements for each pixel. A differential absorption technique (continuum interpolated band ratio) has been used for this purpose. The retrieved AOD and water vapour values were compared with in situ sun-photometer and radiosonde data respectively, indicating good matches. Further, these parameters were used to derive ‘atmospherically corrected surface reflectance and remote sensing reflectance’, for land and water surface respectively, assuming horizontal surfaces having Lambertian reflectance.

Characterization of Species Diversity and Forest Health using AVIRIS-NG Hyperspectral Remote Sensing Data

Abstract: C. S. Jha*, Rakesh, J. Singhal, C. S. Reddy, G. Rajashekar, S. Maity, C. Patnaik, Anup Das, Arundhati Misra, C. P. Singh, Jakesh Mohapatra, N. S. R. Krishnayya, Sandhya Kiran, Phil Townsend and Margarita Huesca Martinez National Remote Sensing Centre, Indian Space Research Organisation, Hyderabad 500 037, India Space Applications Centre, Indian Space Research Organisation, Ahmedabad 380 015, India MS University of Baroda, Vadodara 390 002, India University of Wisconsin, Madison 53706, USA University of California, Davis 95616, USA

Synthesis and Characterization of Nano-selenium and its Antibacterial Response on Some Important Human Pathogens

Abstract: Synthesis of nano-selenium was achieved from sodium selenite by a simple precipitation method using the reducing power of ascorbic acid. The high-speed centrifuge was used to separate selenium nanoparticles from aqueous solution. The selenium nanoparticles were characterized by UV–Vis spectroscopy, X-ray diffraction, Fourier transform-infrared spectroscopy (FT-IR), scanning electron microscopy, energy dispersive X-ray analysis and transmission electron microscope. Presence of various functional groups responsible for the production and stability of the nanoparticles was confirmed by FT-IR. Some of the important human pathogens like Staphylococcus aureus , Escherichia coli and Pseudomonas aeruginosa were used for examining the antibacterial response of selinium nanoparticles. Results of this study demonstrate that synthesized selenium nanoparticles exhibit a spherical shape with average diameter range between 15 and 18 nm. They can be used as an antibacterial agent and also in medicinal applications for the treatment of humans with certain bacterial diseases.

Water Quality Assessment of River Ganga and Chilika Lagoon using AVIRIS-NG Hyperspectral Data

Abstract: Remote sensing is a vital tool to assess water quality parameters in water bodies like rivers, lakes, estuaries and lagoons. All these fall under the category of optically complex waters (case 2), where water-leaving radiance is affected by optically active water constituents and bottom substrate. The present study estimates water quality parameters, viz. turbidity, suspended sediment concentration and chlorophyll in River Ganga in Buxar (Bihar), and Howrah (West Bengal) and Chilika lagoon (Odisha) using hyperspectral reflectance data of AVIRIS-NG. Concurrent ground-truth data of water samples were collected and simultaneous spectro-radiometer measurements were made in synchronous with the AVIRIS-NG flight over the study area. Semi-analytical simulation modelling followed by inversion and contextual image analysis-based methods were used for estimating the water quality parameters. Water turbidity maps were generated for both the study sites. Over Ganga river, water was relatively clear in Buxar (6.87–20 NTU, TSS 42–154 mg/l), while it was extremely turbid in Howrah (50–175 NTU, TSS 75–450 mg/l). In Chilika lagoon, water was more turbid in the northern sector, which may be due to the river input and resuspension from shallow bathymetry. The results suggest that the small-scale changes in turbidity due to point sources like river tributaries or sewerage discharges can be identified using hyperspectral data. The imaging spectroscopy data over water are a key source to find out potential locations of water contamination.

A Practive Faeces Collection Protocol for Multidisciplinary Research in Wildlife Science

Abstract: Faecal samples have become an important noninvasive source of information in wildlife biology and ecological research. Despite regular use of faeces, there is no universal protocol available for faeces collection and storage to answer various questions in wildlife biology. In this study we collected 1408 faeces from ten different species using a dry sampling approach, and achieved 77.49% and 75.25% success rate in mitochondrial and nuclear marker amplifications respectively. We suggest a universal framework to use the same samples to answer different questions. This protocol provides an easy, quick and cheap option to collect non-invasive samples from species living in different environmental conditions to answer multidisciplinary questions in wildlife biology.

An Assessment of the Performance of ISRO’s SCATSAT-1 Scatterometer

Abstract: Suchandra A. Bhowmick, James Cotton, Alexander Fore, Raj Kumar*, Christophe Payan, Ernesto Rodríguez, Anuja Sharma, Bryan Stiles, Ad Stoffelen and Anton Verhoef 5 Space Applications Centre, Indian Space Research Organisation, Ahmedabad 380 015, India Met Office, UK Jet Propulsion Laboratory, California Institute of Technology, USA CNRM, Université de Toulouse, Météo-France, CNRS, Toulouse, France Royal Netherlands Meteorological Institute (KNMI), The Netherlands

Adsorption of arsenic using low cost adsorbents: guava leaf biomass, mango bark and bagasse

Abstract: Adsorbents prepared from inexpensive materials of guava leaf biomass, mango bark and bagasse were studied for As(III) removal from the aqueous solution. The effects of pH, contact time, initial As(III) concentration and adsorbent dosage on the adsorption of As(III) were studied using batch experiments. Adsorption process was also verified with Langmuir, Freundlich, Temkin and Redlich–Peterson models. Langmuir isotherm fitted best in the experimental data. Application of Langmuir isotherm to the system yielded the maximum capacities of 1.35 mg g, 1.25 mg g and 1.05 mg g for bagasse, mango bark and guava leaf biomass respectively, in the range of As(III) concentration as 10–140 mg l. The dimensionless equilibrium parameter, RL, signifies favourable adsorption of As(III) on all adsorbents and was observed to be in the range of 0.029–0.294, 0.021– 0.235 and 0.021–0.234, for bagasse, mango bark and guava leaf biomass respectively (0 < RL < 1). The adsorption process was observed to follow pseudosecond-order kinetic model.

Post-Launch Calibration–Validation and Data Quality Evaluation of SCATSAT-1

Abstract: Here we provide a brief description of the post-launch data quality evaluation and calibration–validation chain of the SCATSAT-1, the second scatterometers mission of Indian Space Research Organisation. This chain is of absolute importance to monitor the satellite health and its impact on its measurements. It also provides us overview of the suitability of the data for various applications. The results show that the SCATSAT instrument is having nominal behaviour, the measurements are of very high quality and is comparable to the reference mission QuikSCAT. The ocean surface winds derived using SCATSAT-1 are having errors less than 1 m/s and hence it is suitable for all operational meteorological and oceanographic applications.

Pesticides use and its Effect on Soil Bacteria and Fungal Populations, Microbial Biomass Carbon and Enzymatic Activity

Abstract: The indiscriminate use of chemical pesticides disturbs the soil environment, thereby affecting flora and fauna including soil microflora, and also the physicochemical properties of the soil, viz. pH, salinity, alkalinity, leading to poor soil fertility. With the application of pesticides, possibilities exist that these chemicals may exert certain effects on non-target soil microorganisms. The soil microbial biomass plays an important role in the soil ecosystem, where they fulfill a crucial role in nutrient cycling and decomposition. A series of field experiments were conducted at farmer’s field at Sitapur, UP with different modules of integrated pest management (IPM) including use of safe formulations. The impact of application of these pesticides on the soil properties including soil microbial populations, microbial biomass carbon and enzymatic activity was assessed. It was observed that soil microbial biomass C content and dehydrogenase activity was influenced by IPM interventions.

Crop Type Discrimination and Health Assessment using Hyperspectral Imaging

Abstract: Rahul Nigam*, Rojalin Tripathy, Sujay Dutta, Nita Bhagia, Rohit Nagori, K. Chandrasekar, Rajsi Kot, Bimal K. Bhattacharya and Susan Ustin Agriculture and Land Eco-system Division, Earth, Ocean, Atmosphere, Planetary Sciences and Applications Area, Space Applications Centre (ISRO), Ahmedabad 380 015, India National Remote Sensing Centre (ISRO), Hyderabad 500 037, India M.G. Science Institute, Ahmedabad 380 009, India Environmental and Resource Sciences, University of California, Davis, CA 95616, USA

Large Losses in Glacier Area and Water Availability by the End of Twenty-First Century under High Emission Scenario, Satluj Basin, Himalaya

Abstract: Glaciers in the Satluj river basin are likely to lose 53% and 81% of area by the end of the century, if climate change followed RCP 8.5 scenario of CNRMCM5 and GFDL-CM3 models respectively. The large variability in area loss can be due to difference in temperature and precipitation projections. Presently, Satluj basin has approximately 2000 glaciers, 1426 sq. km glacier area and 62.3 Gt glacier stored water. The current mean specific mass balance is –0.40 m.w.e. a–1. This will change to –0.42 and – 1.1 m.w.e. a–1 by 2090, if climate data of CNRM-CM5 and GFDL-CM3 are used respectively. We have used an extreme scenario of GFDL-CM3 model to assess the changes in the contribution of glacier melt to the Bhakra reservoir. Mass balance model suggests that glaciers are contributing 2 km3 a–1 out of 14 km3 of water. This will increase to 2.2 km3 a–1 by 2050, and then reduce to 1.5 km3 a–1 by the end of the century. In addition, loss in glacier area by the end of century, will also increase the vulnerability of mountain communities, suggesting need for better adaptation and water management practices.

Adsorption of Orange-G dye by the Dried Powdered Biomass of Chlorella vulgaris Beijerinck

Abstract: Decolourization potential of microalgal biomass of an unicellular green alga ( Chlorella vulgaris ) was studied using different concentrations of Orange-G dye. Several parameters were also optimized for better removal of the tested dye from its aqueous solution. Langmuir and Freundlich models were tested for equilibrium studies and experimental data of the present study are better explained by the Freundlich model. FTIR data showed that five functional groups were probably involved in the adsorption of the dye. The biosorption process using algae (including C. vulgaris ) offers an excellent biosystem for the remediation of final discharge of textile effluents.

Assessment of Cryospheric Parameters Over the Himalaya and Antarctic Regions using SCATSAT-1 Enhanced Resolution Data

Abstract: Antarctica is the focus of scientific studies considering the largest reservoir of terrestrial water in the form of ice and doubling of ice area during winter due to sea-ice growth. The third pole – Himalaya is equally important due to the large extent of snow and ice cover outside the polar regions, which is a major source of water for the Asian countries. At present, the Ku-band scatterometer observing global cryosphere is the SCATSAT-1 launched by India. This article describes the study carried out on different cryospheric parameters using high-resolution (~2.2 km) scatterometer data in the Antarctica and Himalaya. Impact of seasonal variations in snow/ice and ice calving on the backscatter over Antarctica is discussed in detail. A procedure developed for the estimation of sea-ice extent, which yielded overall accuracy of 89%, has been presented and successfully applied for daily monitoring of the Antarctic ice extent for 2017. Surface melting using backscatter and brightness temperature data has been discussed and the contrast between large-sized and small-sized Antarctic ice shelves during the austral summer period of summer 2017–18 is highlighted. The higher average surface melt observed around majority of east Antarctic ice shelves, particularly near the Indian station ‘Maitri’, is of particular interest. Typical surface melting patterns observed over the third largest Antarctic ice shelf, Amery, are discussed in detail. Over northwest Himalaya, derived changes in snow water equivalent (ΔSWE) shows a good correlation between observed and calculated SWE variations. The present study demonstrates that simultaneous availability of high-resolution brightness temperature and backscatter data from SCATSAT-1 provides a unique opportunity to study the polar and mountain cryosphere.

SCATSAT-1 Scatterometer Data Processing

Abstract: SCATSAT-1 carries a Ku-band scatterometer with a scanning pencil beam configuration. It deploys two beams, a vertically polarized outer beam and a horizontally polarized inner beam, to cover a swath of 1800 km. The mission mainly caters to oceanographic applications and weather forecasting, with the data being extensively used for cyclogenesis predictions across the globe and specifically, the tropical region. Since the launch of SCATSAT-1 in September 2016, the satellite and payload performances as well as mission and ground segment operations have been found to be nominal and satisfactory. This article highlights various levels of operational data products as well as algorithms used for deriving radar backscatter and retrieving wind vector data from scatterometer measurements.

Photoluminescence and Raman Studies of α-MoO 3 Doped with Erbium and Neodymium

Abstract: With the objective of development of optoelectronic devices, nowadays the research in this field is centred around the study of photoluminescence emission of rare earth elements present in the lattice of different oxides. Therefore, in this study we prepared samples of molybdenum trioxide doped with neodymium and erbium at concentrations of 1.0% and 2.0%, using solid state reaction technique from powders of MoO 3 , Nd 2 O 3 and Er 2 O 3 . These powders were analysed by X-ray diffraction which determined the presence of phase α-MoO 3 . The morphology of the powders was examined using scanning electron microscopy, which showed that the doped samples have regular and well-defined microplates. The absorption UV-spectra revealed that the optical band gap changed slightly (3.2–3.4 eV) with the Er, Nd and Er–Nd concentrations. The photoluminescence shows emission bands at different wavelengths of the visible spectra as a function of the Er, Nd, and Er–Nd doped. The bands were centred at 748 nm and 808 nm transitions of the Nd 3+ ions respectively. In this region and with excitation wavelength of 350 nm, strong emission lines were not observed for Er. Raman spectroscopy showed typical modes of vibration of α-MoO 3 . Major changes have been noted in the case of samples doped with Er at peaks located between 350 cm −1 and 580 cm –1 .