Sensitivity of inter-annual variation of CO2 seasonal cycle at Mauna Loa to atmospheric transport

Origins of the inter-annual variations of the Mauna Loa atmospheric CO₂ seasonal cycle related to atmospheric transport were examined using a global atmospheric transport model with prescribed land biota CO₂ source functions at 11 land sections. On average, the seasonal variation of atmospheric CO₂ at Mauna Loa is influenced mostly by the Siberian CO₂ flux, followed by temperate Asia and North America. The inter-annual variability of the seasonal cycle is caused mainly by the inter-annual variation in the transport of the Siberian signal to Mauna Loa. The characteristics of the simulated seasonal cycle and its inter-annual variability at Mauna Loa are found to be sensitive to the quality of the wind data used to drive the transport model. Implication of this result is that for studying a long-term variations of atmospheric transport a meteorological data set for driving an atmospheric transport model should be obtained from the same production procedure.