Local emission and long-range transport impacts on the observed concentrations (dry air mole fractions) of CO, CO₂, and CH₄ have been investigated using three years (April 2016 to April 2019) of surface measurements at a tropical rural site, Gadanki (13.5° N, 79.2° E) in Southern peninsular India. Gadanki represents the poor coverage area of Greenhouse Gas (GHG) measurements in India and has both local emission and long-range transport influences on its air masses. All the three gases have shown strong seasonality and diurnal variations. Trend analysis showed a significant decreasing trend in CO (14.3 ± 0.2 ppbv/year) and increasing trends in CO₂ (2.5 ± 1.2 ppmv/year) and CH₄ (11.1 ± 0.03 ppbv/year). CO₂ and CH₄ trends are marginally higher than the global trends (2.2 ± 0.004 ppmv/year and 7.0 ± 0.001 ppbv/year, respectively) for the same period highlighting the sustained local emission impact on the observed concentrations. Among the three species, CO has been the most local emission impacted species with local emission contribution (to the total observed concentration) varying between 4 and 25% during different seasons with a median value always lying above 10% irrespective of the season. In the case of CO₂ and CH₄, the local emission contribution found to vary in the range of 0.8–7% and 0.15–3%, respectively. Long-range transport impact dominance over the local emission is observed in CO₂ and CH₄ during all the seasons. Analysis using MODIS fire count data, Concentration Weighted Trajectory (CWT) and FLEXPART have reconfirmed the combined effect of local and long-range transport impacts on the observed concentrations. Comparison of the IASI MetOp and AIRS satellite data products with surface measurements showed the significant bias and poor representation of the seasonality demonstrating the limitations on the sensitivity of satellite trace gas measurements within the boundary layer.

在热带乡村站点Gadanki进行了三年（2016年4月至2019年4月）表面测量，研究了局部排放和远程运输对观测到的CO，CO ₂和CH ₄浓度（干燥空气摩尔分数）的影响印度南部半岛（13.5°N，79.2°E）。加丹基（Gadanki）代表印度温室气体（GHG）测量的覆盖范围较差的地区，并且对其空气质量具有局部排放和远距离运输的影响。这三种气体均表现出强烈的季节性和昼夜变化。趋势分析显示，CO的下降趋势显着（14.3±0.2 ppbv /年），CO _2的上升趋势（2.5±1.2 ppmv /年）和CH _4的上升趋势（11.1±0.03 ppbv /年）。一氧化碳₂CH ₄和CH ₄趋势在同一时期略高于全球趋势（分别为2.2±0.004 ppmv /年和7.0±0.001 ppbv /年），突显了持续的局部排放对观测浓度的影响。在这三个物种中，CO一直是受当地排放影响最严重的物种，在不同季节中，局部排放贡献（占总观测浓度）在4％至25％之间变化，中位数与季节无关，始终高于10％。在CO ₂和CH ₄的情况下，局部排放贡献分别在0.8–7％和0.15–3％的范围内变化。在CO ₂和CH _4中观察到了对局部排放的远距离运输影响优势在所有季节。使用MODIS火灾计数数据，浓度加权轨迹（CWT）和FLEXPART进行的分析再次确认了局部和远程运输影响对所观察到的浓度的综合影响。IASI MetOp和AIRS卫星数据产品与地面测量结果的比较表明，季节性存在明显的偏差和代表性差，这表明边界层内卫星痕量气体测量的灵敏度受到限制。