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<p>This study investigates the spatio-temporal variability of atmospheric CO<sub>2</sub> across the Indian sub-continent from 2010 to 2020. It examines seasonal fluctuations in atmospheric CO<sub>2</sub> in relation to time–frequency variations, focusing on rainfall, other climatic parameters, and surface fluxes. The analysis is concentrated on four distinct regions of India: Northwest, East and Northeast, Central, and South Peninsular India. Using a least-square error-based harmonic analysis, we identified significant periodicities, primarily dominated by the annual cycle, followed by a semi-annual cycle, in atmospheric CO<sub>2</sub> concentrations and their influencing factors. These factors include climate variables (rainfall, OLR), horizontal advection, and surface fluxes (net terrestrial exchange and combustion emissions). During the Indian monsoon period, a notable decrease in atmospheric CO<sub>2</sub> concentration is observed, attributed to factors such as marine transport driven by the southwest monsoon and low-level cross-equatorial flow, coupled with active vegetation engaging in photosynthetic activities. In contrast, the pre-monsoon season shows elevated CO<sub>2</sub> levels across all regions due to suppressed vegetation growth, crop harvesting, and extensive biomass burning amid prevailing dry conditions. Moderate CO<sub>2</sub> levels are recorded during the post-monsoon and winter seasons, driven by CO<sub>2</sub> fixation by winter crops and the continuous influence of anthropogenic emissions. A multiple linear regression model was employed to determine regional relationships between atmospheric CO<sub>2</sub> and its potential influencing factors throughout different seasons. The seasonal cycles of CO<sub>2</sub> derived from our regression model align well with satellite measurements and NOAA CarbonTracker data. To strengthen validation, we compared model outputs with <i>in-situ</i> CO<sub>2</sub> measurements from four flux tower locations (Gadanki, Sriharikota, Shadnagar, and Ponmudi). These comparisons demonstrate good alignment, reinforcing the model’s robustness in capturing regional CO<sub>2</sub> dynamics. A significant portion of seasonal CO<sub>2</sub> variability can be explained by vegetation dynamics and anthropogenic activities. Additionally, intense convective activities and rainfall are identified as key contributors to the seasonal dynamics of atmospheric CO<sub>2</sub>.</p>

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Spatio-temporal dynamics of atmospheric CO2 over India and its inter-relationship with combustion emissions, ecosystem exchange, and meteorological factors

  • 期刊论文

  • 发表日期：

    2025年9月12日

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  • M Krishnapriya,
  • D R Pattanaik,
  • Amit Kumar,
  • M V Ramana,
  • C V Naidu

摘要

This study investigates the spatio-temporal variability of atmospheric CO2 across the Indian sub-continent from 2010 to 2020. It examines seasonal fluctuations in atmospheric CO2 in relation to time–frequency variations, focusing on rainfall, other climatic parameters, and surface fluxes. The analysis is concentrated on four distinct regions of India: Northwest, East and Northeast, Central, and South Peninsular India. Using a least-square error-based harmonic analysis, we identified significant periodicities, primarily dominated by the annual cycle, followed by a semi-annual cycle, in atmospheric CO2 concentrations and their influencing factors. These factors include climate variables (rainfall, OLR), horizontal advection, and surface fluxes (net terrestrial exchange and combustion emissions). During the Indian monsoon period, a notable decrease in atmospheric CO2 concentration is observed, attributed to factors such as marine transport driven by the southwest monsoon and low-level cross-equatorial flow, coupled with active vegetation engaging in photosynthetic activities. In contrast, the pre-monsoon season shows elevated CO2 levels across all regions due to suppressed vegetation growth, crop harvesting, and extensive biomass burning amid prevailing dry conditions. Moderate CO2 levels are recorded during the post-monsoon and winter seasons, driven by CO2 fixation by winter crops and the continuous influence of anthropogenic emissions. A multiple linear regression model was employed to determine regional relationships between atmospheric CO2 and its potential influencing factors throughout different seasons. The seasonal cycles of CO2 derived from our regression model align well with satellite measurements and NOAA CarbonTracker data. To strengthen validation, we compared model outputs with in-situ CO2 measurements from four flux tower locations (Gadanki, Sriharikota, Shadnagar, and Ponmudi). These comparisons demonstrate good alignment, reinforcing the model’s robustness in capturing regional CO2 dynamics. A significant portion of seasonal CO2 variability can be explained by vegetation dynamics and anthropogenic activities. Additionally, intense convective activities and rainfall are identified as key contributors to the seasonal dynamics of atmospheric CO2.