COMPARISON OF 4 DIFFERENT STOMATAL-RESISTANCE SCHEMES USING FIFE DATA- PART II - ANALYSIS OF TERRESTRIAL BIOSPHERIC-ATMOSPHERIC INTERACTIONS

Stomatal resistance (R-s) forms a pivotal component of the surface ene rgy budget and of the terrestrial biosphere-atmosphere interactions. U sing a statistical-graphical technique, the R-s-related interactions b etween different atmospheric and physiological variables are resolved explicitly from observations made during the First ISLSCP (Internation al Satellite Land Surface Climatology Project) Field Experiment (FIFE) . A similar analysis was undertaken for the R-s parameterization schem es, as used in the present models. Three physiological schemes (the Ba ll-Woodrow-Berry, Kim and Verma, and Jacobs) and one operational Jarvi s-type scheme were evaluated in terms of their ability to replicate th e terrestrial biosphere-atmosphere interactions. It was found that all of the R-s parameterization schemes have similar qualitative behavior for routine meteorological applications (without carbon assimilation) . Compared to the observations, there was no significant difference fo und in employing either the relative humidity or the vapor pressure de ficit as the humidity descriptor in the analysis. Overall, the relativ e humidity-based interactions were more linear than the vapor pressure deficit and hence could be considered more convenient in the scaling exercises. It was found that with high photosynthesis rates, all of th e schemes had similar behavior. It was found with low assimilation rat es, however that the discrepancies and nonlinearity in the interaction s, as well as the uncertainties, were exaggerated. Introduction of CO2 into the analysis created a different dimension to the problem. It wa s found that for CO2- based studies, the outcome had high uncertainty, as the interactions were nonlinear and the schemes could not converge onto a single interpretive scenario. This study highlights the second ary or indirect effects, and the interactions are crucial prior to eva luation of the climate and terrestrial biosphere-related changes even in the boundary layer perspective. Overall, it was found that direct a nd indirect effects could lead the system convergence toward different scenarios and have to be explicitly considered for atmospheric applic ations at all scales.