Jangid et al. (2026) Decadal precipitation variability and atmospheric brown cloud effects: a multi-platform assessment over the Indian subcontinent

Identification

• Journal: Theoretical and Applied Climatology
• Year: 2026
• Date: 2026-01-09
• Authors: Manish Jangid, Avinash Dass
• DOI: 10.1007/s00704-025-06010-z

Research Groups

• School of Environmental Sciences, Jawaharlal Nehru University, New Delhi, India
• Institute for Inclusive Policy and Governance, Chandigarh, India
• Department of Environmental Science, Central University of South Bihar, Gaya, India

Short Summary

This study assessed decadal precipitation variability and atmospheric brown cloud (ABC) effects over the Indian subcontinent from 2000-2019. It found that during 2010-2019, precipitation increased in low-rainfall areas but decreased in high-rainfall and southern regions, with these shifts linked to aerosol optical depth and mechanisms like the Elevated Heat Pump and surface dimming.

Objective

• To investigate the decadal spatio-temporal variation of precipitation patterns and their radiative effects due to atmospheric brown clouds (ABCs) over the Indian subcontinent, specifically examining aerosol type, vertical distribution, and radiative effects across contrasting climatic regions from 2000 to 2019.

Study Configuration

• Spatial Scale: Indian subcontinent [7° N − 38°N; 60°E − 98°E], divided into North-Western Central Indian region (NWCIR: 21°−31° N; 68°−80° E), Indian Core Monsoon Region (ICMR: 21°−27° N; 80°−90° E), and South Indian region (SIR: 9°−21° N; 73°−80° E).
• Temporal Scale: Two decades: D1 (2000–2009) and D2 (2010–2019), with daily datasets. Seasonal analysis: pre-monsoon (March-May), monsoon (June-September), post-monsoon (October-November), and winter (December-February).

Methodology and Data

• Models used: MERRA-2 (Modern-Era Retrospective analysis for Research and Applications, version 2), ERA5 (ECMWF Re-Analysis fifth generation).
• Data sources:
  • Satellite: TRMM (Tropical Rainfall Measuring Mission) 3B42 Version 7 for precipitation (2003-2019). MERRA-2 assimilates AOD from MISR, MODIS, AVHRR.
  • Observation (Ground-based): IMD (Indian Meteorological Department) gridded precipitation data (2000-2018), AERONET (AErosol RObotic NETwork) for aerosol optical depth (AOD).
  • Reanalysis: MERRA-2 (aerosol optical depth, radiative fluxes), ERA5 (meteorological parameters: meridional, zonal, vertical winds, relative humidity).
  • Statistical methods: Ordinary least squares linear regression, Sen’s slope estimator, Mann-Kendall test, two-tailed Student’s t-test (95% confidence level). Data regridded to 1° × 1° horizontal resolution.

Main Results

• A clear decadal shift in precipitation patterns was observed: during 2010-2019 (D2) compared to 2000-2009 (D1), precipitation rates generally increased over regions with lower mean precipitation rates (e.g., northwest India during winter/pre-monsoon).
• Conversely, a decrease in precipitation rates was observed over heavy precipitation regions (e.g., northeast India during monsoon and post-monsoon seasons) and in southern India during pre-monsoon and monsoon periods.
• Decreased precipitation in southern and coastal regions was consistently associated with elevated aerosol optical depth (AOD) and substantial ABC-induced surface dimming.
• Increased aerosol loading (AOD) was associated with enhanced median and extreme precipitation in the northwestern and core monsoon regions, supporting the Elevated Heat Pump (EHP) mechanism.
• The vertical and seasonal distributions of various aerosol loadings (dust, sea salt, anthropogenic) emerged as key modulators of precipitation variability, driving spatially divergent aerosol impacts.

Contributions

• Provides new decadal-scale evidence linking the aerosol component of ABCs to region-specific precipitation responses across the Indian subcontinent, using a multi-platform assessment (satellite, reanalysis, ground-based).
• Offers a long, season-resolved synthesis linking evolving ABC loading to precipitation at subregional scales, addressing a gap in previous studies that focused on shorter periods, single platforms, or national averages.
• Explicitly examines aerosol type, vertical distribution, and radiative effects to provide new insights into why aerosol impacts on precipitation differ between northern, central, and southern India.
• Highlights the dual role of absorbing aerosols (enhancing atmospheric heating/monsoonal winds in the north versus surface dimming/reduced evaporation in the south), supporting both EHP and surface dimming frameworks.
• Underscores urgent regional water management and resilience-planning implications for densely populated, climate-sensitive areas.

Funding

• The study received no external funding.

Citation

@article{Jangid2026Decadal,
  author = {Jangid, Manish and Dass, Avinash},
  title = {Decadal precipitation variability and atmospheric brown cloud effects: a multi-platform assessment over the Indian subcontinent},
  journal = {Theoretical and Applied Climatology},
  year = {2026},
  doi = {10.1007/s00704-025-06010-z},
  url = {https://doi.org/10.1007/s00704-025-06010-z}
}