Kumar et al. (2025) Doppler weather radar-based 5-year climatology of winter storms over the National Capital Region of India

Identification

• Journal: Theoretical and Applied Climatology
• Year: 2025
• Date: 2025-11-10
• Authors: Amit Kumar, M. Mohapatra, Manish Dixit
• DOI: 10.1007/s00704-025-05855-8

Research Groups

• India Meteorological Department, Ministry of Earth Sciences, New Delhi, India

Short Summary

This study presents the first Doppler Weather Radar-based 5-year climatology of winter storms over the National Capital Region of India, characterizing their life period, intensity, size, and movement. It reveals that most storms are short-lived and spatially confined, but a subset of intense, long-lived storms occurs more frequently in polluted and urban-influenced regions, predominantly moving northeastward.

Objective

• To characterize the spatial and temporal distribution of convective systems.
• To classify system intensity using reflectivity thresholds.
• To investigate storm movement direction and propagation speed.
• To assess regional variations in storm duration and frequency.
• To explore the potential influence of local topography and urban pollution on system dynamics.

Study Configuration

• Spatial Scale: A 150 km radius around Delhi, India, encompassing the National Capital Region (NCR), divided into nine grids, each approximately 2500 square kilometers.
• Temporal Scale: A 5-year period (2018–2022) focusing on the winter months of January and February.

Methodology and Data

• Models used: Grid-based framework for storm analysis, centroid-based tracking method for storm movement, and reflectivity thresholds for classifying storm life cycle, size, and intensity.
• Data sources: Raw Level-2 data from the C-band dual-polarized Doppler Weather Radar (DWR) located at Mausam Bhawan, India Meteorological Department (IMD), Delhi.

Main Results

• Over 75% of winter storms persist for less than 180 minutes, with the modal duration being 30–60 minutes, indicating a predominance of short-lived systems.
• A dominant northeastward movement is observed in 71% of storms, aligning with the large-scale steering by upper-tropospheric westerlies associated with Western Disturbances.
• Small-sized storms (less than 20 km x 20 km) dominate across all grids, constituting over 44% of total storms, but Grid 5 (Delhi) shows the highest share of large storms (greater than 31 km x 31 km) at 24%.
• Maximum storm intensities above 45 dBZ are spatially clustered in central and eastern grids, particularly downstream of urban corridors, suggesting the influence of aerosol-cloud interactions.
• Orographic lifting from the Aravalli hill ranges in southern and southwestern grids (Grids 4, 7, 8) plays a vital role in storm initiation.
• Urban pollution and aerosol loading enhance cloud droplet formation, delay early rainout, sustain cloud growth, and strengthen updrafts, contributing to longer-lived and more intense storms over polluted regions like Delhi.

Contributions

• Presents the first Doppler Weather Radar-based climatology of winter storms specifically for Delhi and the National Capital Region of India.
• Highlights the combined roles of large-scale synoptic circulation (Western Disturbances) and localized environmental factors (urban pollution, land use, topography) in modulating winter storm characteristics.
• Provides critical insights for improving storm monitoring and forecasting capabilities in India’s winter weather regime.

Funding

No funding was received to carry out this research.

Citation

@article{Kumar2025Doppler,
  author = {Kumar, Amit and Mohapatra, M. and Dixit, Manish},
  title = {Doppler weather radar-based 5-year climatology of winter storms over the National Capital Region of India},
  journal = {Theoretical and Applied Climatology},
  year = {2025},
  doi = {10.1007/s00704-025-05855-8},
  url = {https://doi.org/10.1007/s00704-025-05855-8}
}