by Siva Sai Kumar Rajana, Sampad Kumar Panda, Sridevi Jade, Chiranjeevi G. Vivek, A. K. Upadhayaya, Arti Bhardwaj, Sonam Jorphail & Gopi Krishna Seemala
We investigated the ionosphere response to the two severe geomagnetic storms in the ascending phase of solar cycle 25 which occurred during the 23-24 March 2023 (SYM-Hmin = −169 nT) and 23-24 April 2023 (SYM-Hmin = −233 nT) using a latitudinally aligned dense network of Global Navigation Satellite System (GNSS) receivers, magnetometers, and digisonde along the Indian longitude sector. The significant variations in TEC during the storm’s main and recovery phases are mainly linked to the influence of westward Disturbance Dynamo Electric Fields (DDEFs). During the initial phase of the March 23-24 geomagnetic storm, no changes in daytime TEC were observed, despite the storm occurring at noon time with a southward IMF Bz due to the influence of electron density in the top side ionosphere. Furthermore, both pre-reversal enhancement (PRE) and ionosphere irregularities are suppressed within two hours of their onset during the main phase of the March 23-24 storm, owing to the westward transition of zonal electric fields from an eastward direction. During the recovery phase of both storms, a daytime positive storm effect is observed over the dip equatorial region, while the beyond equatorial ionization anomaly (EIA) and mid-latitude regions perceived a negative ionospheric storm effect. This phenomenon is attributed to the influence of the dominant westward DDEFs during the period. Moreover, these DDEFs effectively inhibited the equinoctial manifestation of PRE effects and post-sunset ionospheric irregularities during the recovery phase of both storms. These findings are further confirmed with supporting information from TEC recorded by Swarm satellites, model-derived ionospheric electric fields, and thermospheric O/N2. The results from this study may advance the understanding of ionospheric response to severe geomagnetic storms under the prevailing westward DDEFs during the dayside recovery phase, complementing the global efforts for more reliable space weather modeling and prediction services.
by Priya Singh, Aditya Anand, Shweta Rana, Amit Kumar, Sujeet Kumar, Prabudh Goel, Krushna Chandra Gouda, Harpreet Singh
Introduction: The COVID-19 pandemic has caused widespread morbidity, mortality, and socio-economic disruptions worldwide. Vaccination has proven to be a crucial strategy in controlling the spread of the virus and mitigating its impact.
Objective: The study focuses on assessing the effectiveness of COVID-19 vaccination in reducing the incidence of positive cases, hospitalizations, and ICU admissions. The presented study is focused on the COVID-19 fully vaccinated population by considering the data from the first positive case reported until 20 September 2021.
Methods: Using data from multiple countries, time series analysis is deployed to investigate the variations in the COVID-19 positivity rates, hospitalization rates, and ICU requirements after successful vaccination campaigns at the country scale.
Results: Analysis of the COVID-19 positivity rates revealed a substantial decline in countries with high pre-vaccination rates. Within 1–3 months of vaccination campaigns, these rates decreased by 20–44%. However, certain countries experienced an increase in positivity rates with the emergence of the new Delta variant, emphasizing the importance of ongoing monitoring and adaptable vaccination strategies. Similarly, the analysis of hospitalization rates demonstrated a steady decline as vaccination drive rates rose in various countries. Within 90 days of vaccination, several countries achieved hospitalization rates below 200 per million. However, a slight increase in hospitalizations was observed in some countries after 180 days of vaccination, underscoring the need for continued vigilance. Furthermore, the ICU patient rates decreased as vaccination rates increased across most countries. Within 120 days, several countries achieved an ICU patient rate of 20 per million, highlighting the effectiveness of vaccination in preventing severe cases requiring intensive care.
Conclusion: COVID-19 vaccination has proven to be very much effective in reducing the incidence of cases, hospitalizations, and ICU admissions. However, ongoing surveillance, variant monitoring, and adaptive vaccination strategies are crucial for maximizing the benefits of vaccination and effectively controlling the spread of the virus.
by Stella Jes Varghese, Sajani Surendran, Kavirajan Rajendran, Subimal Ghosh, Akio Kitoh, Karumuri Ashok
The increase in water holding capacity of the atmosphere with temperature, given by the Clausius-Clapeyron (CC) relationship, describes the changes in extreme rainfall intensities at warmer atmospheric states. We study the characteristics of extreme rainfall events (EREs) during the Indian summer monsoon season with respect to thermodynamic changes and precipitation-scaling over the Indian subcontinent and its homogeneous rainfall zones. We utilize outputs from a present-day climate simulation and a time-slice future climate change projection experiments of a high-resolution global climate model. Large changes are seen for very EREs (vEREs) which suggests their sensitivity to warmer temperatures. In future, the altered radiative forcing will heat up the upper atmosphere, stabilize it and offset the effect of increasing humidity on precipitation intensity. Our analysis also suggests that more convective clouds and the interplay of increased moisture content and circulation will result in future changes in EREs.
by Iranna Gogeri, K. C. Gouda & T. Sumathy
Atmospheric carbon dioxide (CO2) is considered as most significant greenhouse gas (GHG) in terms of its global warming potential and human-caused emissions. In Indian context, CSIR Fourth Paradigm Institute has established continuous monitoring of GHG stations at Hosakote nearer to Bengaluru, India. In the present study, seasonal autoregressive integrated moving average (SARIMA) model has been developed based on evaluation criteria, considering its statistical performance and ability to capture the trend and patterns in CO2 concentration at station scale which will be useful in regional studies. The present work addresses to find an optimized SARIMA configuration for the accurate prediction of the CO2 concentration and to provide a projection of the same in the near future i.e., till 2027. The proposed model is being trained with data from October 2016 to December 2020 and the performance is validated by comparing simulated results with the observed data for recent 2 years (2021 and 2022). The statistical measures for the model’s performance has been evaluated by computing the important error parameters and correlation analysis.The study demonstrated that the SARIMA model is very much suitable for forecasting the CO2 concentrations, as it provided accurate predictions by showing good agreement with the observed values.The predicted data align well with observations and capture the seasonal variations, suggesting that model developed in this study has captured the patterns and trends in the CO2 concentration data effectively and can be considered a reliable tool for predicting future CO2 concentrations. Also, the projection made till 2027 using the optimised model and it is predicted that there is slight increase in the CO2 concentrations over the Bengaluru region in the near future time i.e., 2023–2027. These inferences will contribute for understanding the CO2 concentration trends in at station scale and provide valuable insights for policymakers, researchers, and stakeholders involved in climate change mitigation and environmental planning.
by T. S. Shrungeshwara, Bhavani Narukula, Sridevi Jade, Sapna Ghavri, Chiranjeevi G. Vivek & I. A. Parvez
We report the present day GNSS velocities (2015–2021) and strain rates in Himachal, Kashmir and Ladakh Himalaya covering the rupture zones of the 2005 Muzaffarabad earthquake and the 1905 Kangra earthquake. Geodetic strain rates estimated from GPS velocities of about 58 sites spanning last two decades of measurements indicate a mean compression rate of − 32.5 ns/year (nanostrain/year) and dilatation of − 37.3 ns/year. Seismic strain rates are estimated using both the instrumental period (1964–2021) and historical earthquakes since 1500 AD in this region. Seismic strain rates during the instrumental period of the past 50 + years indicate a mean compression rate of − 28.1 ns/year and it slightly decreases to − 21.7 ns/year after including the historical earthquakes of the past 520 years. The Azimuth of the seismic strain tensor for the instrumental and historic periods and geodetic strain tensor is broadly consistent with orientation of major faulting in this region suggesting uniform compression over a long-time interval justifying combined analysis of the strain rate field to determine the seismic potential of the region. Composite analysis of geodetic and seismic strain rates and the associated moments estimate the accumulated strain budget of ~ 1E + 21 Nm in the past 520 years which has a potential of generating future earthquake of Mw > 8 in this segment of Northwest Himalaya.
Source: https://doi.org/10.1038/s41598-023-48997-3
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