Impact of a Regional Drought on Land and Atmospheric Carbon over the North America
The spatiotemporal extent of a regional drought’s impact on land-atmosphere carbon and their mechanistic linkages are still poorly understood. Allowing carbon-water-energy feedback in an ensemble of coupled land-atmosphere simulations, this study quantifies induced changes in meteorology and carbon caused by an idealized 3-month meteorological drought over to the lower Mississippi River Valley (~500,000 km2). The imposed drought leads to a 23% Gross Primary Production (GPP) reduction in the drought area and the GPP reductions in some remote areas that are adjacent to the imposed drought through the changes in remote meteorology, particularly by the induced precipitation. The effect of the meteorological anomalies on GPP is greater, by at least an order of magnitude, than that of the atmospheric CO2 anomalies. While the magnitude of induced CO2 anomalies near the land surface can be as large as 3.57ppm, the column-averaged CO2 increases up to 0.78ppm and thus is below the precision limit (~1ppm) of current greenhouse gas (GHG) observing satellites. Spatially, the CO2 anomalies cover an area up to three times of that of the imposed drought, which suggests that the atmospheric transport needs to be considered in the interpretation of carbon anomalies in the atmosphere.