Browsing by Author "R. K. Mall"

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A framework for city-specific air quality health index: a comparative assessment of Delhi and Varanasi, India
(Institute of Physics, 2025) Franciosalgeo George; Pallavi Joshi; Sagnik Dey; R. K. Mall; Santu Ghosh
Air quality index (AQI) is a crucial tool for communicating the health risks of air quality to the public. However, the current AQI in India does not consider the health impacts of exposure to air pollutants, necessitating the development of air quality health index (AQHI). Here, we proposed a framework for developing city-specific AQHI that better reflects local air quality and associated health risks using air pollution and health data from two polluted and densely populated cities in north India—Delhi and Varanasi (Delhi: 2013-2017; Varanasi: 2009-2016). We also constructed a pooled AQHI by combining data from both cities. Using concentrations of ambient fine particulate matter (PM2.5), nitrogen dioxide, and ozone, we applied generalized additive models with a quasi-Poisson link, using daily mortality counts as the outcome, excluding suicide and accidental deaths. A 10 µg m−3 increase in PM2.5 was associated with mortality increases of 0.17% (95% CI: 0.01-0.34) in Varanasi, 0.20% (95% CI: 0.1-0.29) in Delhi, and 0.16% (95% CI: 0.08-0.24) in the pooled model. The city-specific AQHI classified 21.8% of days in Delhi as ‘Satisfactory’ versus 18.2% by the pooled index, while 24.2% of days were ‘Poor’ compared to 30.1% under the pooled index. In Varanasi, 6.8% of days were ‘Good’ under the city-specific AQHI, compared to 9.3% by the pooled index, with 15.7% of days classified as ‘Poor’ versus 19.3% by the pooled index. Our results suggest that a single-pooled AQHI may misrepresent local air quality and associated health risks. Since AQHI values are derived from excess mortality risk estimates, a city-specific AQHI ensures a more accurate reflection of local pollution-related health impacts, supporting targeted public health interventions. We recommend accessibility of health data to enable developing AQHI for non-attainment cities in India and use it to track progress towards cleaner air. © 2025 The Author(s). Published by IOP Publishing Ltd.
Assessing climate-driven phenological responses of tomato crops under future climate change trajectories: A Central India perspective
(Elsevier B.V., 2025) Pashupati Nath Singh; Prashant Kumar Srivastava; Bhawana Sharma; R. K. Mall
Climate change poses a serious challenge to global agriculture, particularly by altering crop phenology and yield dynamics. This study investigates the phenological responses of tomato crops to anticipated climate scenarios by employing a Crop Simulation model, Decision Support System for Agrotechnology Transfer (DSSAT). Simulations were conducted for Central India under two Shared Socioeconomic Pathways (SSP 4.5 and SSP 8.5) across three temporal windows: near-century (2010–2039), mid-century (2040–2069), and far-century (2070–2099). Historical climate data and calibrated genetic coefficients were used to project shifts in flowering and fruiting stages under varying climate conditions. The study assessed the impacts of projected changes in temperature (T), solar radiation (Srad), and precipitation (PPT) patterns on phenological development. Climate input datasets were sourced from IMD, IPCC, and six CMIP6- Global Climate Models. Results revealed a distinct phenological advancement, characterised by a reduction in days to flowering and fruiting, along with a concurrent decline in tomato yield (Ton/ha) across all future timeframes. Increased growing season temperatures and marginal reductions in Srad were observed to accelerate crop development, while altered rainfall patterns influenced spatial variability in production. Notably, enhanced evapotranspiration demand driven by warming trends may be partially moderated by decreased radiation levels. Spatial rainfall analysis indicated intensified PPT in central zones, whereas western and northwestern regions may experience monsoonal weakening and prolonged dry spells. Model performance showed robust agreement with observed yields (R = 0.78), with validation metrics—MAE = 5.9, RMSE = 6.93, and Bias = -1.43—demonstrating consistent predictive accuracy with slight underestimation. The Nash–Sutcliffe Efficiency (NSE = 0.59) further affirms the model's applicability under future climate conditions. This research underscores the utility of process-based models in decoding climate–phenology–yield relationships and provides critical insights to inform climate-resilient agricultural strategies for sustainable tomato production in vulnerable agro-ecological regions. © 2025
Does climate change induce desertification in Gujarat?
(Springer Science and Business Media Deutschland GmbH, 2025) R. Bhatla; Richa S. Singh; Priyanka; R. K. Mall; Sanjay Bist
Land degradation refers to the decline in economic and biological productivity of land caused by climatic variability and human activities, leading to disrupted ecosystem functions. Gujarat, located in the dry and semi-arid region of India, is particularly vulnerable to these processes due to its dependence on monsoon precipitation, which is characterized by significant variability. This study examines rainfall data from the India Meteorological Department for the period 2000 to 2020 and satellite-derived Normalized Difference Vegetation Index (NDVI) values for 2001, 2011, and 2021 to assess spatial and temporal trends in desertification across selected districts. The analysis indicates an overall increasing trend in monsoonal rainfall during the two decades, but this increase is unevenly distributed, with certain districts experiencing more pronounced variability. Remote sensing data reveal a complex pattern of vegetation dynamics. Districts like Porbandar and Bharuch show improvements in NDVI values, suggesting enhanced vegetation cover and potential recovery from land degradation. Conversely, Vadodara exhibits declining NDVI trends, highlighting escalating risks of desertification, likely driven by intensified anthropogenic pressures such as industrialization and deforestation. This research highlights the critical interplay between climatic factors and land use changes in shaping regional ecological health. The findings underscore the need for proactive and region-specific land management strategies to mitigate desertification. With the help of reliance on robust satellite-based monitoring and high-resolution climatic data, this study provides a replicable framework for understanding and combating land degradation in similar vulnerable districts. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2025.
India's Drought Challenge: Insights From CMIP6 Models on Historical and Future Climate Scenarios
(John Wiley and Sons Ltd, 2025) R. Bhatla; Aashna Verma; Akash Vishwakarma; R. K. Mall
Droughts, wielding devastating impacts on India, serve as the focal point of this research paper that explores key facets of India and its six distinct homogeneous regions' future climate by investigating the frequency, intensity, and underlying mechanisms of droughts. Utilising 10 General Circulation Models (GCMs) from the Coupled Model Intercomparison Project Phase 6 (CMIP6), spanning 1901 to 2014, our study employs a Multi-Model Ensemble (MME) approach under Shared Socioeconomic Pathways: SSP245 and SSP585 scenarios for the near (2031–2060) and far (2071–2100) future. Examining historical and projected scenarios, our findings reveal shifting patterns in drought frequency and intensity across regions, identifying North-west India (NWI) and North-central India (NCI) as potential hotspots. The study delves into atmospheric dynamics, revealing their role in drought vulnerabilities. Future trends under SSP245 and SSP585 trajectories underscore the impact of anthropogenic activities, with SSP585 projecting heightened drought risks, especially in NWI and NCI. The analysis of atmospheric physics uncovers the influence of moisture, convective processes, and regional climatic factors, attributing intensified drought risks to amplified atmospheric instability, particularly in NWI. Near-future precipitation patterns reflect regional nuances driven by atmospheric physics and climatic factors. Transitioning to the far future reveals persistent precipitation patterns, emphasising the role of emission trajectories in shaping drought conditions. Statistical analyses indicate an increase in drought intensity and duration, with NWI witnessing the maximum number of extreme droughts. Divergent regional patterns necessitate planned, adaptive policies to address evolving climate dynamics. © 2025 Royal Meteorological Society.
Spatio-Temporal Changes in Cold Wave Characteristics Over the Diverse Meteorological Sub-Divisions of India
(Birkhauser, 2025) Saumya Singh; R. K. Mall; Pradip Kumar Gautam
Cold wave (CW) and Severe Cold wave (SCW) prevail over India as a seasonal episode during winter season. The present study analyzes the changing spatio-temporal characteristics and trends of cold waves over India's meteorological subdivisions from 1951 to 2021 (Dec–Feb). It uses minimum temperature data obtained from the India Meteorological Department (IMD) at a spatial resolution of 0.5° × 0.5°. A declining trend in both CW and SCW days is found with a decrease of − 0.29 days/decade in CW days and 0.02 days/decade in SCW days. The study also explored the trend of spells of three, five and seven days of CW and SCW and found a significantly decreasing trend of − 0.02 days/decade and − 0.05 days/decade in 3 and 5-day SCW spell respectively. A consistent significant increase of 0.027 °C/decade in minimum temperature post 1980s is also reported in the study with a simultaneous decrease in cold wave. While the northwestern and northern meteorological subdivision record highest CW and SCW spells, a declining trend is reported in these regions, highest being in West Rajasthan (− 1.3 days/decade) and Punjab (− 1.3 days/decade). A significant increasing trend has been observed in CW, SCW days/spells in the eastern, eastern coastal and southern subdivisions such as Bihar (0.16 days/decade), Jharkhand (0.05 days/decade) and Odisha (0.2 days/decade). Overall, the study reports a decline in cold waves and identifies new cold wave-prone regions in the country. The study also highlights the emerging severe impact on agriculture sector in the scenario of declining cold extremes over major wheat producing belts. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2025.
Synergistic associations of ambient air pollution and heat on daily mortality in India
(Elsevier Ltd, 2025) Jeroen de Bont; Ajit Rajiva; Siddhartha Mandal; Massimo Stafoggia; Tirthankar Banerjee; Hem H. Dholakia; Amit Garg; Vijendra Ingole; Suganthi Jaganathan; Itai Kloog; Bhargav Krishna; Kevin James Lane; R. K. Mall; Jyothi S. Menon; Amruta Nori-Sarma; Dorairaj Prabhakaran; Abhiyant Suresh Tiwari; Yaguang Wei; Gregory A. Wellenius; Joel D. Schwartz; Poornima Prabhakaran; Petter L.S. Ljungman
Background: Limited studies have evaluated the interaction between ambient air pollution and heat on mortality, especially in regions such as India, where extreme levels of both exposures occur frequently. Accordingly, we aimed to investigate the potential synergistic effects between ambient air pollution and heat on daily mortality in India. Methods: We applied a time-series analysis for ten cities in India between 2008–2019. We assessed city-wide daily particulate matter ≤ 2.5 μm (PM2.5) and temperature levels using two nationwide spatiotemporal models. We estimated city-specific exposure-outcome associations through generalised additive Poisson regression models, and meta-analysed the associations. To evaluate the interaction between PM2.5 and air temperature (modelled at lag 0–1), a product term was incorporated between linear PM2.5 and non-linear air temperature. From this model, we estimated the effect of air pollution for increasing levels of temperature, and vice versa. Findings: Among ∼ 3.6 million deaths, we found that the association of PM2.5 on mortality was particularly stronger beyond the 75th percentile of temperature. When we compared the associations of PM2.5-mortality at the 75th and 99th temperature percentile, we observed an increase from 0.8 % (95 % CI: −0.3 %, 1.9 %) to 4.6 % (95 % CI: 2.9 %, 6.5 %) increase in mortality per 10 μg/m3 increments, respectively. In addition, we observed a 22.0 % (95 % CI: 13.5 %, 31.2 %) increase in daily mortality risk due to an increase in temperature from the 75th to the 99th city-specific percentiles. Percent change in mortality risk increased linearly from 8.3 % (95 % CI: 2.2 %, 14.9 %) when daily PM2.5 was 20 μg/m3 to 63.9 % (95 % CI: 38.7.%, 93.7 %) at 100 μg/m3. Interpretation: Our findings reveal a substantial synergistic interaction between ambient air pollution and temperature in India. This calls for efforts to tangibly reduce common sources of air pollution and climate change to immediately lower their combined effects on daily mortality and mitigate their long-term health consequences. © 2025 The Authors
The dynamical influence of energy fluxes in modulating variability of the Indian summer monsoon
(Elsevier Ltd, 2025) R. Bhatla; Archana Maurya; Aashna Verma; R. K. Mall; Sanjay Bist
The surface heat fluxes have a significant role in shaping the Indian summer monsoon (ISM) dynamics. The present study investigates the climatological tricadal and decadal variability of surface energy fluxes viz., net shortwave radiation flux, latent heat flux (LHF) and net heat flux (NHF) during ISM season. For that purpose, a long-term (1961–2020) reanalysis data sets derived from the European Centre for Medium-Range Weather Forecasts fifth-generation (ERA5) and National Center for Environmental Prediction-National Centre for Atmospheric Research reanalysis (NCEP-NCAR) has been considered. Significant regional differences and changing patterns have been observed in the distribution of energy fluxes over southern peninsular India, Arabian Sea (AS), Bay of Bengal (BoB), Equatorial Indian Ocean (EIO), and Southern Indian Ocean. The BoB and AS emerge as vital moisture sources, directly contributing to the monsoon rainfall over eastern, central and western India, respectively. A significant positive change in LHF is observed over AS (9W/m2) and EIO (12W/m2) regions, whereas over the BoB region, a negative departure of −8 W/m2 has been persistent in the recent tricade. These changes correspond to the significant negative anomalous patterns of NHF, i.e., −11 W/m2 over AS and −18 W/m2 over EIO, alongside the highest increase in NHF value over the BoB regions (20 W/m2). The pronounced tricadal phase shift of surface fluxes over AS, EIO, and BoB is identified as a contributing factor influencing ISM rainfall. © 2025 Elsevier Ltd
Upscaling residential solar rooftop in Uttar Pradesh: review of policy, practices and stakeholders perspective, identification of challenges and solutions
(Elsevier Ltd, 2025) Ashish Tiwari; R. K. Mall; Maheswar Rupakheti
This research paper examines the barriers and solutions related to the adoption of residential rooftop solar (R-RTS) in Uttar Pradesh. Despite government policy interventions, R-RTS uptake remains limited compared to the state's energy consumption-based potential. The study systematically analyses key adoption issues, stakeholder perspectives, policy landscape and identifies critical issues such as policy gaps, implementation challenges, and stakeholder collaboration deficits through policy review, stakeholder analysis, and adoption drivers. Methodologically, the study employs a mixed qualitative approach, including document analysis, stakeholder consultations, and field insights. The study proposes following actionable solutions: i) Policy interventions for subsidies beyond 3 kW. ii) Relaxation on system capacity limits. iii) Enhanced compensation for excess electricity injected into the grid. iv) Strategies to improve vendor participation. v) Addressing DISCOM inefficiencies regarding net meter availability and verification delays. vi) Speedier subsidy transfers. vii) Targeted awareness campaigns.The research highlights the importance of post-installation service ecosystems, advocating for skilled manpower development and product standardization to improve local service access. The intended policy outcome is to create a more enabling environment for residential R-RTS adoption, supporting climate goals and decentralized renewable energy expansion. This paper provides a structured roadmap for policymakers, vendors, consumers, and implementors to scale rooftop solar adoption in Uttar Pradesh. © 2025 Elsevier B.V.