Browsing by Author "Pramod Kumar Yadava"

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Impact of climate change on water quality and its assessment
(Elsevier, 2022) Pramod Kumar Yadava; Harshbardhan Kumar; Anubhuti Singh; Vinod Kumar; Sunita Verma
Worldwide changes in climatic conditions are encouraged by increase in the concentration of Green House Gases (GHGs), are widely perceptible in terms of continuous changing patterns of superficial temperature, rainfall pattern, wind-flow patterns, radiations, and other life-threatening weather conditions. With a wider consent from the regional and global scientific communities, Intergovernmental Panel on Climate Change (IPCC) has indisputably summarized that kind of fact. Therefore, in this ongoing era of global climate-change, the assessment of probable impact on water and its quality, being the most prominent and reliable resource for human existence, become a significant task. Lots of assessment and review study have been reported on the possible impact of climate-change on water cycling and precipitation pattern. Recently, in-situ quality assessment, satellite observational assessment, and modeling simulation studies are in progress to assess the possible impact of climate change on the quality of available water. These studies mostly reported that the rising temperature and hence changing climatic conditions are capable of varying the ecological balance of water as well its qualitative contents either by its indirect impact or by direct impact by performing various biochemical alternations, as the rise in the water temperature and changes in extremes like flash-flood worsen various reasons of pollution caused in water bodies. In a natural water system, sediment load, nutrients availability, dissolved organic carbon, and essential zoo planktonic community are found to be in a delicate balance. Change in the flow pattern and thus augmentation in nutrients concentration, predictable variation in climatic phenomenon leads to periodic phytoplankton blossoms and alteration of the ecological tropical balance. The resultant dissolved oxygen (DO) level is varied constantly and algal-blooms may range to the perilous level to affect negatively. In addition, melting glaciers and consequent rising levels of the sea are expected to encompass the zones of salinization toward freshwater resources, which results in the reduction in available freshwater resources in the coastal areas. Additionally, variations in the qualitative value of water are predictable to affect nutriment accessibility, steadiness, access, and consumption. All these detrimental effects of changing climate hence water quality can adversely impact food security and hence enhancing the vulnerability of the agriculturalists and civilizations of our rural culture surviving in arid regions like Asian and African deltas (IPCC, Technical report on climate change and water, June 2008). © 2023 Elsevier Inc. All rights reserved.
Influence of meteorological parameters on lightning flashes over Indian region
(Springer, 2023) Pramod Kumar Yadava; Ajay Sharma; Swagata Payra; R.K. Mall; Sunita Verma
Abstract: Lightning flashes (LF) and their association with meteorological variables that can influence the occurrence of lightning have been assessed in detail over the Indian domain, i.e., the Convective Available Potential Energy (CAPE), Relative Humidity (RH), Total Column Water Vapour (TCWV), Surface Temperature (ST) and Outgoing Longwave Radiation (OLR). A high-resolution dataset of LF has been retrieved from the Lightning Imaging Sensor (LIS) on board the Tropical Rainfall Measuring Mission (TRMM) satellite. The CAPE, TCWV, RH and ST from 1998 to 2013 are retrieved using ERA-Interim monthly/annual climatology while OLR was retrieved from NCEP datasets. The seasonal analysis shows that most LF occur during the pre-monsoon period (March, April, and May) (0.40–0.45 flash/km2/day) over northeast region. During the monsoon season (June, July, and August), the LF dominates over northern India (0.35–0.40 flash/km2/day). The seasonal variation of CAPE shows the maximum (1250–2250 J/kg) during pre-monsoon over the coastal area of NE and SE regions. TCWV and RH show the maximum in monsoon season over northeastern part, which is 50–70 kg/m2 and 60–80%, respectively. The dependence of LF on meteorological parameters varies from region to region, as is evident from statistical analysis. Maximum LF occurred over the NE (0.049 flash/km2/day) region, followed by the EC (0.041 flash/km2/day) and the lowest in the WC (0.027 flash/km2/day) region of India. The LF showed a significant correlation with CAPE over NE and EC of India because of higher humidity content values over the coastal regions, which form graupel through convection. Over the WH, LF and CAPE showed a good correlation (r = 0.94) because of orographic convection processes. Further, TCWV showed significant correlation with LF over WH (0.89) and minimum over WC (0.23) region. Principal component analysis (PCA) shows that lightning is well correlated with CAPE, RH, TCWV and ST over most regions in India. However, lightning is not significantly correlated with OLR. Understanding the meteorology of lightning across the Indian region can inform forecasting of possible lightning events and is relevant for assessing lightning for human, wild risk and climate projections. Research highlights: The regional-scale meteorological variables associated with lightning are identified.Due to the regional orography, lightning flashes show high correlation in proximity to meteorological variables.The spatio-temporal distribution shows that most of the lightning flashes occur during March, April and May (MAM) months over North East region.The impact of meteorological variables is visible as the study's threshold values change over time. © 2023, Indian Academy of Sciences.
Rapid flash flood calamity in Chamoli, Uttarakhand region during Feb 2021: an analysis based on satellite data
(Springer Science and Business Media B.V., 2022) Sunita Verma; Ajay Sharma; Pramod Kumar Yadava; Priyanshu Gupta; Janhavi Singh; Swagata Payra
The present study investigates the accelerating factors for extreme flash flood at Chamoli district of Uttarakhand on 7 February 2021. The Sentinel-2A and 2B satellite data have been used to depict changes in pre-flood (16th of January) i.e., 5 years of 2016 to 2021 to post-flood (10 February, 2021) situation over the study domain. Vegetation and snow-cover from 2016 to 2021 has been obtained using Normalized Difference Vegetation Index (NDVI) classification over study area. Normalized Difference Water Index (NDWI) is used to extract the pre and post-flood water pixels for flood inundation mapping. The Cartosat-1 digital elevation model (DEM) product is used for drainage pattern and stream order mapping. Correlation between the meteorological parameters such as snowfall, wind speed and wind direction of Nanda Gunti peak during the time of flood with the flood event is analysed. The overall results indicate heavy snowfall (4.22 mm/day) over Nanda Gunti hills followed by high wind speed (23 km/hr.) that might have led to initiation of avalanche/landslide, giving rise to massive flash flood and eroded approximately 0.0263 km3 volume of landmass along with snow cover. Further, the 5 years NDVI analysis shows decrease in vegetation near Rishiganga and Alaknanda, a higher order river streams, is also crucial factor for flood intensification that caused massive destruction within the study area. The work highlights the importance of mapping of intense events and underline factors to reduce the impact and losses in case of future events. © 2022, The Author(s), under exclusive licence to Springer Nature B.V.
Role of Lightning NOx in Ozone Formation: A Review
(Birkhauser, 2021) Sunita Verma; Pramod Kumar Yadava; D.M. Lal; R.K. Mall; Harshbardhan Kumar; Swagata Payra
This paper provides an overview on the spatiotemporal distribution and evolution mechanism of lightning. The predominant mechanism of ozone formation in the upper troposphere is lightning-induced precursors such as oxides of nitrogen (NOx), carbon monoxide (CO), and hydrocarbons (HC). Lightning-induced NOx (LNOx) is one of the major ordinary sources of NOx in the upper atmosphere, particularly in the tropical region, but it is still highly uncertain as to the exact quantity. Various ground measurements, satellite observations and modelling studies on the lightning and global NOx source rate have been extensively studied and compared to find the variability in estimated global lightning-induced NOx. Lightning can influence the climate via the production of nitrogen oxides (NO + NO2 = NOx) followed by the production of ozone, another efficient greenhouse gas. The global annual lightning NOx of 5 ± 3 Tg year−1 has been estimated by modelling studies with an ozone creation efficiency of 6.5 ± 4.7 times that of surface NOx sources. Understanding and quantifying the processes and production of lightning and LNOx is important for assessment of ozone concentrations and its associated impacts on the global climate. © 2021, The Author(s), under exclusive licence to Springer Nature Switzerland AG.
The major lightning regions and associated casualties over India
(Springer, 2020) Pramod Kumar Yadava; Manish Soni; Sunita Verma; Harshbardhan Kumar; Ajay Sharma; Swagata Payra
Lightning, a climate-related highly localized natural phenomenon, claims lives and damage properties. These losses could only be reduced by the identification of active seasons and regions of lightning. The present study identifies and correlates the lightning-prone regions with the number of casualties reported over India at the state/union territory level. The seasonal and monthly composite satellite data of Lightning Imaging Sensor for the duration of 16 years (1998–2013) have been analyzed in this study for the identification of the major lightning-prone seasons and regions over India. The casualties due to lightning have also been estimated using data from Accidental Deaths and Suicides in India, National Crime Record Bureau report of India. The spatial distribution analysis reveals that lightning occurs mostly in hilly regions over India throughout the year (26 flash/sq. km/yr) and, however, causes lesser casualties because of the sparse population over the hilly terrain. The seasonal analysis reveals the most lightning phenomena occur during the pre-monsoon period (40–45 flash/sq. km/yr) over the northeast region of India. During the winter period, the lightning dominates over the northern parts of India such as Jammu and Kashmir. The state-wise casualties’ study reveals that maximum casualties are reported in Madhya Pradesh (313 deaths), Maharashtra (281 deaths) and Orissa (255 deaths) on an average per annum. The favorable climatic conditions, such as availability of moisture content, unstable atmosphere and strong convection, cause severe cases of lightning over the regions of Orissa and Maharashtra. © 2020, Springer Nature B.V.