Thoughts on Earth System Modeling: From global to regional scale

Earth system modeling - in which the atmosphere, the hydrosphere, the biosphere, and the geosphere are all taken into account - will form the basis of the future of modeling. Our discussion focuses on some modeling challenges that we believe to be key issues to be addressed, not only on a global, but also on a regional scale. On the one hand, there is the need to improve our knowledge about emissions and atmospheric boundary layer processes to take earth system modeling forward. On the other hand, improved earth system modeling can help in advancing understanding of the chemical composition of the natural atmosphere and the resilience of the earth atmosphere. The paper aims at stimulating an interdisciplinary discussion within the modeling community, both developers and users, regarding the setting of good operational practices and priorities for future research. Special attention is devoted to chemical transport models.