Enhanced Representation of Landscape Heterogeneities in ICON-LAND: Implications for Hydrology and Carbon Processes

Carbon fluxes play an important role in the Earth System, influencing climate, vegetation dynamics, and biogeochemical cycles. Accurately simulating these fluxes using Earth System Models is essential to understand and predict future climate change. However, these simulations depend on often poorly represented characteristics like small-scale landscape heterogeneities as well as small-scale variations in surface hydrology and temperature, which can impact carbon processes.

In this study, we analyze simulations performed with the ICON climate model, focusing on recent enhancements to its land surface component, ICON-Land. The modifications aim for a better represention of  small-scale heterogeneities by introducing distinct tiles within each grid cell that represent local states of moisture and temperature and can exchange water and heat fluxes between each other. The characteristics of these tiles are derived from high resolution topographical data. These improvements are expected to capture soil moisture and temperature dynamics - which are key drivers of carbon processes - in a more realistic way.

Our preliminary results, which are derived from simulations with prescribed atmospheric forcing, indicate that the improved representation of landscape heterogeneities in ICON-Land affects its hydrology and carbon processes. Specifically, we see an increase in soil moisture and evapotranspiration as well as Gross Primary Productivity and soil respiration in our simulations. These changes demonstrate that the improved model has a significant effect on interactions between the land surface and the atmosphere, and thereby might affect the global carbon cycle.

This study highlights the importance of representing small-scale landscape features in climate models and demonstrates the potential of the enhanced ICON-Land model to improve the simulation of carbon processes. Further analysis is underway to comprehensively assess the impacts of these modifications on the global carbon budget and fully-coupled climate projections.