Browsing by Author "Srivastava A.K."

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    Diurnal Variation of Rain Drop Size Distribution over the Western Ghats of India
    (National Institute of Science Communication and Policy Research, 2024) Kumar A.; Srivastava A.K.; Chakravarty K.; Srivastava M.K.
    Joss-Waldvogel Disdrometer (JWD) measurements at the High-Altitude Cloud Physics Laboratory (HACPL: 17.56�N, 73.4�E, above 1373 m MSL), Mahabaleshwar were investigated for determining the diurnality of the drop size distribution (DSD) associated with the precipitation characteristics over the Western Ghats of India. The JWD data for the period from 2015 to 2019 were collected and examined during the Indian Summer Monsoon (ISM) season. The number concentration of rain droplets of various diameters is considerably varying with the rain rate (R) and type of precipitating cloud. With increasing the value of R, rain droplets having larger diameter concentration significantly increases, and the distribution tail moves towards the biggest droplets. The average value of reflectivity (Z), R, liquid water content (LWC), mass-weighted mean diameter (Dm), and normalized intercept parameter (log10Nw) was found to be higher for the heavy rainfall (Rhigh ?10 mm h-1) as compared to the low rainfall (Rlow < 10 mm h-1) during the entire study period. The gamma distribution of DSD shows significant differences during the low and heavy precipitation on different time periods (e.g., 00-06, 06-12, 12-18, 18-23 LST). The number of rain events contributing to the total accumulated rain varies with time. The maximum number of rain events occurred during 12-18 LST, with 23.6 % rain events of low rainfall and 4.9% of heavy rainfall. The bimodality is observed in the diurnal variation of Dm, R, and Z, with the largest peak recorded in the late afternoon hour (13-16 LST) and the second crest in the early morning hour (05 LST). At the same time, the log10Nw value drops down, indicating the lowest concentration of rain droplets. � 2024 National Institute of Science Communication and Policy Research. All rights reserved.
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    Intensification mechanisms and moisture dynamics of super cyclonic storm �Amphan� over the Bay of Bengal: Implications for aerosol re-distribution
    (Elsevier B.V., 2024) Singh V.; Srivastava A.K.; Gupta A.; Konduru R.T.; Singh A.; Singh S.; Kumar A.; Bisht D.S.; Singh A.K.
    The present research investigates the dynamics and underlying causes contributing to the exceptional intensity of Super Cyclonic Storm (SuCS) Amphan (16th to 21st May 2020) over the Bay of Bengal (BoB), as well as its impact on aerosol redistribution along the four cities of eastern coast and north-eastern India. Notably, the SuCS was formed during the first phase of the COVID-19 lockdown in India, giving it a unique aspect of study and analysis. Our analysis based on 30 years of climatology data from Modern-Era Retrospective Analysis for Research and Applications, Version 2 (MERRA-2) reanalysis reveals �positive� monthly anomalous winds (0.8 to 1.6 m/s) prevailed over the central BoB for May 2020. The present study further found the evolution of �barrier layer thickness�(BLT) leading up to landfall, noting a thickening trend from 8 to 3 days before landfall, contributing to maintaining warmer sea surface temperatures near the coast. Additionally, utilizing European Centre for Medium-Range Weather Forecasts (ECMWF), reanalysis version-5 (ERA-5) data, a mean positive sea surface temperature (SST) anomaly of 0.8 to 1 �C was observed �before� cyclone period (10�15 May 2020) near the cyclogenesis point. A detailed examination of Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) vertical cross-section plots during the cyclone's intensification stage reveals the presence of high-altitude clouds composed primarily of ice crystals. Further, analysis also indicates that the cyclone transported Sea-salt PM2.5 aerosols from the ocean, dispersing them in the landfall region.The aerosol optical Depth (AOD) data obtained from the National Aeronautics and Space Administration's (NASA) �Clouds and the Earth's Radiant Energy System (CERES)� mission and MERRA-2 were also analysed, revealing that the cyclone redistributed aerosols over the Bengal basin region (mainly over �Kolkata') and three other nearby cities along the track of the cyclone (i.e., Bhubaneswar (Odisha) Agartala (Tripura) and Shillong (Meghalaya) respectively). � 2024 Elsevier B.V.
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    Long-Term Trend in Black Carbon Mass Concentration Over Central Indo-Gangetic Plain Location: Understanding the Implied Change in Radiative Forcing
    (John Wiley and Sons Inc, 2024) Mehrotra B.J.; Srivastava A.K.; Singh A.; Parashar D.; Majumder N.; Singh R.S.; Choudhary A.; Srivastava M.K.
    For the first-time, analysis of a decade long measurement of Black Carbon mass concentration (BC) was carried out at a representative central Indo-Gangetic Plain (IGP) location, Varanasi (25.30�N, 83.03�E, 79�m asl), from 2009 to 2021 to understand its physical, optical, and radiative impacts. During the 13-year study period, the daily BC mass concentration was found to vary between 0.07 and 46.23�?g�m?3 (mean 9.18���6.53�?g�m?3) and showed a strong inter-annual and intra-annual variations. The inter-annual variability of BC showed a significant decreasing trend (?0.47�?g�m?3�yr?1), with a maximum during the post-monsoon (?1.86�?g�m?3�yr?1) and minimum during the pre-monsoon season (?0.31�?g�m?3�yr?1). The Black Carbon Aerosol Radiative Forcing (BC-ARF) at the top of the atmosphere (BC-ARFT), surface (BC-ARFS), and within the atmosphere (BC-ARFA) was found to be 10.3���6.4, ?30.1���18.9, and 40.5���25.2�W�m?2, respectively. BC-ARF also showed a strong inter-annual variability with a decreasing trend for BC-ARFT (?0.47�W�m?2�yr?1) and BC-ARFA (?1.94�W�m?2�yr?1), while it showed an increasing trend for BC-ARFS (1.33�W�m?2�yr?1). Concentrated weighted trajectories (CWT) and potential source contribution function (PSCF) analyses were performed at the station to determine the potential source sectors and transport routes of BC aerosols. These analyses revealed that the long-range source of BC at Varanasi originates from the upper and lower IGP, central highlands, southern peninsular region, Pakistan, and even from the Central East Asia region. � 2024. American Geophysical Union. All Rights Reserved.
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    Lysosome-targeting solid state NIR emissive donor-acceptor molecules: a study on photophysical modulation through architectural distinction
    (Royal Society of Chemistry, 2024) Kushwaha A.K.; Srivastava A.K.; Kumar P.; Kumar A.; Srikrishna S.; Singh R.S.
    The prevalence of the D-A strategy in achieving red-shifted emission has been established through designing D-A molecules of D-A-D and A-D-A constructs. Architectural control over such D-A systems integrates solid state NIR emission with lysosome tracking and sets a multifarious goal of photophysical modulation in a comprehensive way. In particular, two compounds, CPM-1 (D-A-D) and CPM-2 (A-D-A), have been synthesized by introducing carbazole-based donors and difluoroboron acceptors. Lysosome targeting and imaging have been achieved through incorporation of a morpholine unit, which ultimately imparts viscosity sensitivity to the construct. The fluorophores exhibited significant emission in solution along with distinctive solvatochromism, viscochromism and TICT. A comparative account of these competitive photophysical properties revealed the superior charge transfer properties of the A-D-A construct (CPM-2), while the D-A-D molecule (CPM-1) was found to be a better molecular rotor with marked viscochromism. The solid state NIR emission has been found to be much more intense in CPM-1 relative to CPM-2, which further highlights the influence of structural aspects on photophysical behvaiour. Theoretical studies further established the distinctive characteristics of ground and excited states in these compounds. Owing to its excellent viscochromic behvaiour, CPM-1 has been successfully utilized in lysosome targeting in wild-type Drosophila fly gut tissues through co-localization studies. � 2024 The Royal Society of Chemistry.
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    Smart sensing solutions for the growth of agriculture
    (Elsevier, 2024) Srivastava A.K.; Saxena S.; Yadav S.K.; Ashok P.
    The global population is growing suddenly, and resources are being used up quickly. We need creativity, especially in agriculture, to feed such a vast population. The most technologically advanced and demanding industry now is agriculture. There is a serious concern about how quickly the condition of the land is declining. We must apply contemporary agricultural assistance to end hunger, improve the farmer's financial situation, and so directly enhance the financial situation of the nation. One of the buzzwords of the moment is "precision farming" or "smart farming," and with the development of technology, particularly in the areas of Internet of Things and artificial intelligence, agriculture is reaching new heights. The creation of various uses and sensors for farming growth is greatly aided by IoT and sensor networks. This motivates us to offer the classification of various smart sensing applications and breakthroughs in agriculture. We will discuss a variety of sensors in this chapter that will be useful in forestry and agriculture. � 2024 Elsevier Inc. All rights reserved.
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    Sustainable water management in rice cultivation reduces arsenic contamination, increases productivity, microbial molecular response, and profitability
    (Elsevier B.V., 2024) Majumdar A.; Upadhyay M.K.; Giri B.; Yadav P.; Moulick D.; Sarkar S.; Thakur B.K.; Sahu K.; Srivastava A.K.; Buck M.; Tibbett M.; Jaiswal M.K.; Roychowdhury T.
    Arsenic (As) and silicon (Si) are two structurally competitive natural elements where Si minimises As accumulation in rice plants, and based on this two-year field trial, the study proposes adopting alternating wetting and drying (AWD) irrigation as a sustainable water management strategy allowing greater Si availability. This field-based project is the first report on AWD's impact on As-Si distribution in fluvio-alluvial soils of the entire Ganga valley (24 study sites, six divisions), seasonal variance (pre-monsoon and monsoon), rice plant anatomy and productivity, soil microbial diversity, microbial gene ontology profiling and associated metabolic pathways. Under AWD to flooded and pre-monsoon to monsoon cultivations, respectively, greater Si availability was achieved and As-bioavailability was reduced by 8.7 � 0.01�9.2 � 0.02% and 25.7 � 0.09�26.1 � 0.01%. In the pre-monsoon and monsoon seasons, the physiological betterment of rice plants led to the high rice grain yield under AWD improved by 8.4 � 0.07% and 10.0 � 0.07%, proving the economic profitability. Compared to waterlogging, AWD evidences as an optimal soil condition for supporting soil microbial communities in rice fields, allowing diverse metabolic activities, including As-resistance, and active expression of As-responsive genes and gene products. Greater expressions of gene ontological terms and complex biochemical networking related to As metabolism under AWD proved better cellular, genetic and environmental responsiveness in microbial communities. Finally, by implementing AWD, groundwater usage can be reduced, lowering the cost of pumping and field management and generating an economic profit for farmers. These combined assessments prove the acceptability of AWD for the establishment of multiple sustainable development goals (SDGs). � 2024 Elsevier B.V.