Atmospheric Methane Variability During Upwelling Events in the Southern Coast of Java, Indonesia

Abstract

AbstractAs a greenhouse gas with a radiative forcing of 0.48 ± 0.05 W/m2, methane can trap heat in the atmosphere better than carbon dioxide. Methane is produced naturally from the ocean, especially during coastal upwelling events due to the effect of the biogeochemical process. This study investigates the contribution of the seasonal coastal upwelling events towards atmospheric methane variability in the southern coast of Java, Indonesia, from 2011 to 2020. The result shows that Atmospheric methane concentrations along the southern coast of Java have an annual cycle with strong seasonal variability that peaks around boreal autumn with a concentration around 1800–1820 ppb/volume each year. Seasonal upwelling begins in May and peaks in July. Atmospheric methane concentrations are significant in July and peak in September. Hence there is a two-month lag between upwelling intensification and seasonal variations in plankton and atmospheric methane concentrations above the upwelling system. In addition, the interannual variability of atmospheric methane concentration is related to Indian Ocean Dipole that coincides with increased upwelling intensity and phytoplankton abundance.KeywordsMethaneCoastal upwellingSouthern coast of JavaIndian Ocean