Influence of Meteorology and interrelationship with greenhouse gases (CO₂ and CH₄) at a suburban site of India

Abstract. Atmospheric greenhouse gases (GHGs), such as carbon dioxide (CO₂) and methane (CH₄), are important climate forcing agents due to their significant impacts on the climate system. The present study brings out first continuous measurements of atmospheric GHGs using high-precision LGR-GGA over Shadnagar, a suburban site of Central India during the year 2014. The annual mean CO₂ and CH₄ over the study region are found to be 394 ± 2.92 and 1.92 ± 0.07 ppm (μ ± 1σ) respectively. CO₂ and CH₄ show a significant seasonal variation during the study period with maximum (minimum) CO₂ observed during pre-monsoon (monsoon), while CH₄ recorded the maximum during post-monsoon and minimum during monsoon. Irrespective of the seasons, consistent diurnal variations of these gases are observed. Influences of prevailing meteorology (air temperature, wind speed, wind direction, and relative humidity) on GHGs have also been investigated. CO₂ and CH₄ show a strong positive correlation during winter, pre-monsoon, monsoon, and post-monsoon with correlation coefficients (R_s) equal to 0.80, 0.80, 0.61, and 0.72 respectively, indicating a common anthropogenic source for these gases. Analysis of this study reveals the major sources for CO₂ are soil respiration and anthropogenic emissions while vegetation acts as a main sink, whereas the major source and sink for CH₄ are vegetation and presence of hydroxyl (OH) radicals.