MIPAS OCS-measurements confirm gross primary production in the Amazon region of different vegetation models

Uptake of atmospheric CO2 (gross primary production, GPP) and of carbonyl sulfide (OCS) by plants is highly correlated. Contrary to CO2 , which to a great extent is respired again, uptake of carbonyl sulfide is irreversible. For this reason, measurement of atmospheric OCS is a promising approach to estimating regional GPP. OCS fluxes in the Amazon region corresponding to various vegetation models were used for modelling of atmospheric OCS and compared to MIPAS satellite measurements (left) in the tropical upper troposphere (250 hPa). The OCS distribution measured above the tropics corresponds to a GPP-value (right, dark green diamond) in the middle of the model range(right, upper row). This work has been published in Geophys. Res. Lett.

Understanding the magnitude of tropical gross primary production is critical for carbon cycle modeling and climate projections, but this quantity is poorly constrained at regional scales. In the approach presented here, OCS concentrations driven by surface flux scenarios encompassing a wide range of GPP estimates for the Amazon basin were simulated. The model output was compared to satellite retrievals and a regional GPP estimate of 2375+-914 g(C) m^-2 yr^-1 was found, consistent with previous estimates, including the TRENDY model ensemble range of 1431-3812 g(C) m^-2 yr^-1. TRENDY provides an ensemble of results from dynamic global vegetation models.