Effects of Air Temperature, Atmospheric Pressure, and Wind Speed on Methane Emissions in Yonghwasil Reservoir, South Korea

According to the IPCC National Greenhouse Gas Inventory, reservoirs are classified as flooded areas and require methane (CH₄) emission estimation. CH₄ emissions from reservoirs, characterized by ebullition and diffusion, primarily increase with temperature but are suppressed when reservoirs are frozen. However, these emissions are influenced not only by temperature but also by other conditions, making it difficult to understand with a single value of the CH₄ emission factor provided by the IPCC. The CH₄ emissions from the Yonghwasil Reservoir in South Korea were measured using the eddy covariance method to analyze their behavior under varying meteorological conditions. CH₄ emissions were positively correlated with air temperature with negligible emissions observed at air temperatures below 8 °C. Therefore, CH₄ emission rates during the summer season are significantly higher than those in winter. From August to October, more than 60% of CH₄ was emitted as ebullition. In contrast, from November to January, total CH₄ emissions decreased, with a resulting 80% from diffusion. Additionally, atmospheric pressure negatively influenced CH₄ emission but was correlated with air temperature. Wind speed had no observable effect on CH₄ emissions at low temperatures but contributed to increased emissions under high-temperature conditions.