Atmospheric carbon dioxide over the Arabian Peninsula: Variability and associated sources

Abstract

This study uses near-decade-long OCO-2 satellite measurements of column-averaged dry-air carbon dioxide (CO₂) mole fraction (XCO₂) to understand CO₂ dynamics across the Arabian Peninsula (AP). The XCO₂ over the AP exhibits strong seasonality, with considerably high and low concentrations during spring and autumn, respectively. Local CO₂ fluxes, predominantly from anthropogenic sources, do not display seasonal variations, resulting in minimal impact on the seasonal XCO₂ cycle across the AP. Analyses of CarbonTracker model outputs reveal a considerable north-to-south transport of CO₂, mainly from Europe and adjacent areas and confined between the low and middle levels of the atmosphere. The seasonal XCO₂ cycle observed in the AP clearly replicates the seasonality of this transport pattern. Furthermore, a cross-correlation analysis shows a lag of approximately 1 month in CO₂ concentrations between Europe and the AP, with the former preceding the latter. The transport of CO₂ from Europe is influenced by considerable variations in local fluxes across the Europe. From winter to early spring, net positive CO₂ fluxes occur due to high respiration, increasing local CO₂ levels. Conversely, from summer to early autumn, net negative fluxes arise from enhanced uptake, reducing local CO₂ concentrations. These concentrations of CO₂ are subsequently transported to the AP, driven by synoptic-scale systems (shamal winds) moving toward the region.

The evolution of El Niño conditions considerably amplifies the XCO₂ levels over the AP by up to approximately 1 ppm. Notably, during the peak phase of the recent 2015–2016 El Niño, we noted strongly positive anomalies over the southern latitudes, which subsequently migrated to the AP.