Development and evaluation of ecosystem-atmospheric chemistry interactions in the ECHAM-HAMMOZ-iMAPLE model

Most existing studies simulate ecosystem influences on atmospheric pollutants using prescribed vegetation datasets, while feedbacks from atmospheric chemistry to terrestrial ecosystems are rarely represented. Here, we couple the chemistry-climate model ECHAM6.3–HAM2.3–MOZ1.0 (ECHAM-HAMMOZ) with the interactive Model for Air Pollution and Land Ecosystems (iMAPLE) to enable fully dynamic, two-way interactions between atmospheric chemistry and terrestrial ecosystems. Biogenic volatile organic compounds, including isoprene (IPP) and monoterpenes (MTP), are simulated by iMAPLE and interactively participate in chemical reactions in HAMMOZ. Simulated leaf area index and stomatal conductance modulate dry deposition velocities, thereby influencing atmospheric chemical concentrations. In turn, the modeled ozone affects vegetation productivity through stomatal uptake. Relative to the original model, the coupled system exhibits notable changes in atmospheric composition and ecosystem productivity. Enhanced IPP and MTP emissions reduce surface ozone concentrations in high-latitude regions, while dynamically simulated ozone variability induces a seasonal reduction in terrestrial gross primary productivity (GPP). In addition, spatial heterogeneity in stomatal conductance alters ozone dry deposition patterns. By explicitly representing these coupled feedback processes, the integrated ECHAM–HAMMOZ–iMAPLE framework improves the realism of biosphere–atmosphere interactions and provides a useful tool for studying atmosphere–terrestrial ecosystem coupling.