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<p>Surface PM<sub>2.5</sub> mass reconstructed from MERRA-2 (Modern Era-Retrospective analysis for Research and Applications) chemical species is widely used to assess aerosol-climate interactions and human health impacts, globally. However, species-wise validation of MERRA-2 PM<sub>2.5</sub> against in-situ measurements remains sparse over India due to limited ground-based aerosol speciation data. This study presents the first species-wise validation of MERRA-2 PM<sub>2.5</sub> components (organic carbon (OC), black carbon (BC), sulfate, sea-salt, and dust) using year-long (2019) in-situ measurements of PM<sub>2.5</sub> and its chemical constituents at three geographically distinct Indian sites—Bhopal (central India), Mesra (eastern India), and Mysuru (southern India). Across the study sites, with reference to in-situ species, MERRA-2 OC showed variable agreement, ranging from underestimation (− 23%) to overestimation (+ 22%), while sulfate was predominantly underestimated (− 31% to − 0.36%). Dust and sea-salt were consistently overestimated (+ 36% to + 65% and + 33% to + 300%, respectively), with poor sea-salt correlations (correlation coefficient &lt; 0.2). The annual mean reconstructed MERRA-2 PM<sub>2.5</sub> mass (excluding nitrate) underestimated in-situ PM<sub>2.5</sub> by 9–27%. Incorporation of estimated nitrate, derived from nitrate-to-sulfate ratios from the&#xa0;CAMS (Copernicus Atmosphere Monitoring Service) reanalysis, reduced the underestimation to 9–17% at Mesra and Mysuru, and resulted in a slight overestimation (2%) at Bhopal. Mann-Kendall trend analysis (1999–2019) of the MERRA-2 species revealed increasing anthropogenic aerosol species (sulfate, OC, and BC), particularly over eastern and central India, likely driven by coal-based power generation and residential biomass burning. These validated, species-wise MERRA-2 PM<sub>2.5</sub> products provide a robust supplementary resource for aerosol, air-quality, climate, and health assessments across India.</p> Graphical Abstract <p></p>

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Evaluation of MERRA-2 PM2.5 species at three locations in India and their historical (1999–2019) trends

  • 期刊论文

  • 发表日期：

    2026年4月16日

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  • Sandeep Devaliya,
  • Sayak Patra,
  • Prem Maheshwarkar,
  • Ankur Bhardwaj,
  • Diksha Haswani,
  • Deeksha Shukla,
  • Ramya Sunder Raman,
  • Abisheg Dhandapani,
  • R. Naresh Kumar,
  • Jithin K. P.,
  • Lokesh Kaggere

摘要

Surface PM2.5 mass reconstructed from MERRA-2 (Modern Era-Retrospective analysis for Research and Applications) chemical species is widely used to assess aerosol-climate interactions and human health impacts, globally. However, species-wise validation of MERRA-2 PM2.5 against in-situ measurements remains sparse over India due to limited ground-based aerosol speciation data. This study presents the first species-wise validation of MERRA-2 PM2.5 components (organic carbon (OC), black carbon (BC), sulfate, sea-salt, and dust) using year-long (2019) in-situ measurements of PM2.5 and its chemical constituents at three geographically distinct Indian sites—Bhopal (central India), Mesra (eastern India), and Mysuru (southern India). Across the study sites, with reference to in-situ species, MERRA-2 OC showed variable agreement, ranging from underestimation (− 23%) to overestimation (+ 22%), while sulfate was predominantly underestimated (− 31% to − 0.36%). Dust and sea-salt were consistently overestimated (+ 36% to + 65% and + 33% to + 300%, respectively), with poor sea-salt correlations (correlation coefficient < 0.2). The annual mean reconstructed MERRA-2 PM2.5 mass (excluding nitrate) underestimated in-situ PM2.5 by 9–27%. Incorporation of estimated nitrate, derived from nitrate-to-sulfate ratios from the CAMS (Copernicus Atmosphere Monitoring Service) reanalysis, reduced the underestimation to 9–17% at Mesra and Mysuru, and resulted in a slight overestimation (2%) at Bhopal. Mann-Kendall trend analysis (1999–2019) of the MERRA-2 species revealed increasing anthropogenic aerosol species (sulfate, OC, and BC), particularly over eastern and central India, likely driven by coal-based power generation and residential biomass burning. These validated, species-wise MERRA-2 PM2.5 products provide a robust supplementary resource for aerosol, air-quality, climate, and health assessments across India.

Graphical Abstract