और लेख ...

by Swagata Mukhopadhyay, Shantikumar S. Ningombam, Akihiro Uchiyama, Sonam Jorphel, Chiranjeevi G. Vivek, T.S. Shrungeshwara, Sreedevi P., Tsuneo Matsunaga, Som K. Sharma, Pawan Gupta, Dorje Angchuk, Sridevi Jade

Sun-sky radiometer (model POM-01) is commonly used for studying aerosol optical and physical properties at selected aerosol-specific channels. Although the instrument is equipped with a precipitable water vapor (PWV) channel at 940 nm, the inbuilt software does not provide a tool for estimation of PWV. Hence, the current study adopted a new methodology to estimate PWV from three high-altitude ( 3400 m MSL) sites, Hanle, Merak, and Leh, located in Ladakh, India. The retrieval algorithm focuses on the precise estimation of the calibration constant () and coefficients and using modified Langley plots in two different methods. The estimated average value of is 0.59 ± 0.09 which is very close to those commonly used in global studies. Further, the estimated and values from both methods are found to be similar, which may be due to the advantages of the dry and high-altitude environment, where the annual total column water vapor is typically less than 6 mm. The estimated PWV using observations at selected full clear and stable atmospheric conditions compares well with satellite, AERONET, GPS, reanalysis and empirical model data with correlation coefficient varying from 0.91 to 0.97. Further, the estimated propagated root mean square error (rmse) varies from 0.37 mm to 2.58 mm. These results indicated that sun-sky radiometer derived PWV showed good consistency with the derived PWV from independent data sources at the three sites.

Source: https://doi.org/10.1016/j.atmosenv.2026.121789

by Imtiyaz A. Parvez and Sanjeev Ekka

The Himalayas rank among the world’s most seismically active regions, as evidenced by major historical earthquakes, including the 1905 Kangra (Mw 7.8), 1934 Bihar–Nepal (Mw 8.2), 1950 Assam (Mw 8.4), 2005 Kashmir (Mw 7.6), and 2015 Gorkha (Mw 7.8) events. These earthquakes underscore the ongoing tectonic activity along the Himalayan arc and have caused substantial human and economic losses. Seismic hazard assessment is a critical tool for mitigating such impacts, informing preparedness efforts, risk reduction strategies, and policy formulation. Significant advancements have been made in recent decades in assessing seismic hazard and risk across the Himalayas. This article reviews key developments in probabilistic and deterministic seismic hazard studies, integrating both historical and instrumental earthquake data. Notably, peak ground accelerations (PGA) in certain Himalayan regions surpass 0.6 g, with areas near the 1897 and 1950 Assam earthquake epicenters recording extreme PGA values of 1.2–1.3 g. These zones also exhibit high ground velocities and permanent displacements, reflecting the severe ground-shaking potential of large Himalayan earthquakes. The article further explores how local geological conditions and source characteristics influence ground motion, emphasizing their role in microzonation studies. Despite progress, critical research gaps remain, particularly the need for high-resolution seismic hazard mapping across the Himalayan arc to enhance risk reduction and resilience-building efforts.

Source: https://doi.org/10.1007/s43538-025-00626-5

by Payoshni Samantray & Krushna Chandra Gouda

Cloudbursts are brief, intense rainfall occurrences that present significant risks to human life, infrastructure, and ecosystems, especially in the Indian Himalayan Region (IHR). Despite their damaging characteristics, predicting these events remains challenging due to their localized nature, the influence of complex terrain, and a lack of high-resolution observational data. Therefore, enhancing the simulation and comprehension of such occurrences is crucial for improved forecasting and disaster readiness. This research introduces a high-resolution computational modeling technique utilizing the Weather Research and Forecasting (WRF) model to replicate cloudburst events in the Indian Himalayan Region (IHR) during the monsoon season of 2022. These extreme weather phenomena, marked by intense and localized rainfall, are hard to forecast because of the region's complex terrain and convective dynamics. In this study six representative cloudburst events from Himachal Pradesh, Uttarakhand, and Jammu & Kashmir were simulated at a resolution of 3 km using six-hourly NCEP-FNL reanalysis data. The analysis concentrated on critical atmospheric mechanisms such as vorticity, convective instability (CAPE, CINE), moisture availability, and orographic lifting. The model outputs were validated against daily rainfall data from the India Meteorological Department (IMD), Global Precipitation Measurement Mission (GPM), and the CPC MORPHing technique (CMORPH). The model demonstrated a strong correlation with IMD data (correlation coefficient of 0.84 and RMSE of 45.07 mm), although performance varied with satellite-based datasets. This study contributes to understanding the simulation of cloudburst events using high-resolution regional modeling and multiple observational validations.

Source: https://doi.org/10.1007/s40808-025-02680-w

by Siva Sai Kumar Rajana, Sambit Prasanajit Naik, Sampad Kumar Panda, Chiranjeevi G. Vivek, Sridevi Jade

Myanmar, located at the convergence of the Indian and Sunda plates, is one of the most seismically active and tectonically complex regions in Southeast Asia. Despite the high seismic hazard, limited ionospheric research has been conducted to understand earthquake-related atmospheric and ionospheric disturbances in this region. The Mw 7.7 Myanmar earthquake that occurred near Mandalay on 28 March 2025 has been considered in this work to examine seismo-ionospheric coupling along the active Sagaing Fault. Using GNSS-derived Total Electron Content (TEC) data, this study identifies both co-seismic and pre-seismic ionospheric anomalies. Multiple Receiver-Satellite (R-S) pairs reveal coherent, temporally correlated perturbations peaking around 0635 UT, indicative of upward-propagating seismic-induced Acoustic Gravity Waves (AGWs). The disturbance amplitudes decreased with distance from the epicenter, with dominant frequencies (3–5 mHz) consistent with seismically induced Traveling Ionospheric Disturbances (TIDs). Horizontal propagation speed of 1.19 km/s confirm the acoustic wave origin of these TEC perturbations. Prominent ionospheric anomalies are detected in the western side of the epicenter, corresponding to the fault rupture zone. These localized, directional perturbations indicate the clear coupling between the strike-slip fault dynamics and ionospheric disturbances. A significant regional TEC reduction detected three days prior to the event under geomagnetically quiet conditions suggests Lithosphere-Atmosphere-Ionosphere (LAI) coupling, likely linked to stress-induced radon emissions or electric field changes. The timing and characteristics of these anomalies reinforce the potential of TEC monitoring as an effective earthquake precursor. The findings not only demonstrate the sensitivity of TEC data to both pre- and post-seismic disturbances but also highlight the potential of TEC-based monitoring as a viable early warning tool, particularly in inter-plate settings where conventional seismic networks may be sparse or underdeveloped. Such ionospheric precursor detection can play a crucial role in enhancing seismic hazard forecasting and preparedness in geologically complex and high-risk regions like Myanmar.

https://doi.org/10.1016/j.asr.2025.11.015

by Puja Sahu, P. K. Mohanty & Krushna Chandra Gouda

Climate change has direct effect on rice crop production, resulting in an impact on food security in tropical countries like India. The coastal state of Odisha, situated in the country's eastern region, also suffered from crop production/yield due to the regional climate change. In this research work, the multi-source long term data analysis is being carried out to quantify the climate-crop relation in the state of Odisha. The analysis of rainfall, temperature, Kharif crop (rice) yield and production for the past three decades in Odisha at district scale is carried out. The study based on the cluster analysis of different physiographical regions i.e. coastal plain (CP), river catchment (RC) and mountainous zone (MZ). The region wise climatology, interannual variability, and trend analysis of both rainfall and temperature and the rain/temperature days are computed using the data over 30 (1993–2022) years. The variability of annual and monsoon rainfall is comparatively higher in the CP and RC than in MZ. The monsoon rainfall trend seems to be decreasing in the CP region, increasing in the MZ and no trend over RC. The analysis infers a negligible (0.01 °C/year) temperature trend in the state. The correlation result suggested that the Kharif rice crop yield & production well correlated with the summer monsoon rainfall over RC and MZ at 90% confidence levels. The rice production in the state shows increasing trend in RC as compared to other two regions. The results suggest a good correlation between the rainfall and rice crop production observed in RC and MZ regions. Similarly, temperature also correlates better with the Kharif crop production and yield in CP as compared to other regions. The district scale analysis also indicated that strong correlation (95%) of rice crop yield with temperature is observed in 10 districts and the relation of crop production and rainfall is strong in 12 districts. The impact of large-scale process like ENSO on the district scale Kharif yield/production also assessed. The analysis signifies the global, local, and direct impact of climate patterns on rice production at district and regional scales. This study opens a scope for the potential use of the integrated approach to address the impact of climate change on a state's agriculture and food sector.

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सीएसआईआर-राष्ट्रीय डेटा विज्ञान एवं कृत्रिम बुद्धिमत्ता संस्थान

Retrieval of precipitable water vapor from sun-sky radiometer (POM-01) at 940 nm absorption band: Calibration, measurement and validation

Mapping seismic hazards in the Himalayas

Studying the dynamics of cloudburst events over Indian Himalayan region using model simulation

Seismo-ionospheric anomalies associated with the 2025 Mw 7.7 Myanmar earthquake: a case study

Quantifying weather-rice crop production relationships across different physiographical zones in Odisha, India