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This paper updates the results obtained earlier with the climate model developed at the A.M. Obukhov Institute of Atmospheric Physics of the Russian Academy of Sciences (IAP RAS CM) and describing the impact of atmospheric sulfur dioxide on the terrestrial carbon cycle. Since no global data are available for the near-surface SO2 concentration, a statistical model was used to reconstruct its concentration from appropriate data on surface sulfate concentrations; the coefficients of this model were tuned by using the output of the RAMS-CMAQ atmospheric chemistry and transport model. The results obtained in this study are generally consistent with data reported earlier. Specifically, the most significant SO2 impact on the terrestrial carbon cycle was found to be for southeastern North America and for Europe. However, this impact for southeastern Asia obtained in this study is considerably weaker than the value obtained earlier, which can be explained by the excessive moisture content in the atmosphere used in the IAP RAS CM for this region. [ABSTRACT FROM AUTHOR]

This paper examines long-term eddy covariance data from 18 European and 17 North American and Asian forest, wetland, tundra, grassland, and cropland sites under non-water-stressed conditions with an empirical rectangular hyperbolic light response model and a single layer two light-class carboxylase-based model. Relationships according to ecosystem functional type are demonstrated between empirical and physiological parameters, suggesting linkages between easily estimated parameters and those with greater potential for process interpretation. Relatively sparse documentation of leaf area index dynamics at flux tower sites is found to be a major difficulty in model inversion and flux interpretation. Therefore, a simplification of the physiological model is carried out for a subset of European network sites with extensive ancillary data. The results from these selected sites are used to derive a new parameter and means for comparing empirical and physiologically based methods across all sites, regardless of ancillary data. The results from the European analysis are then compared with results from the other Northern Hemisphere sites and similar relationships for the simplified process-based parameter were found to hold for European, North American, and Asian temperate and boreal climate zones. This parameter is useful for bridging between flux network observations and continental scale spatial simulations of vegetation/atmosphere carbon dioxide exchange. [ABSTRACT FROM AUTHOR]