Model of the Regional Coupled Earth system (MORCE): Application to process and climate studies in vulnerable regions

The vulnerability of human populations and natural systems and their ability to adapt to extreme events and climate change vary with geographic regions and populations. Regional climate models (RCM), composed by an atmospheric component coupled to a land surface scheme and driven over ocean areas by prescribed sea surface temperature, have been developed to produce fine scale regional climate change information useful for impact assessment and adaptation studies. Although RCM can be sufficient for many applications, the Earth system is composed of the physical, chemical, biological, and social components, processes, and interactions that together determine the state and dynamics of Earth, including its biota and human occupants. Developing regional Earth system models has thus two primary motivations: (1) with respect to climate science, to improve modeling capabilities and better understand coupled processes at regional scales and (2) to support stakeholders who aim to use climate information for regionally-specific impact assessment and adaptation planning. IPSL in collaboration with ENSTA-ParisTech, LOPB, and CERFACS developed the MORCE (Model of the Regional Coupled Earth system) platform for process and climate studies of the regional Earth system. The original aspects of the MORCE platform are (1) the integration of a large number of coupled compartments and processes (physical and biogeochemical processes in the ocean, atmosphere and continent), (2) the transferability of the numerical platform to different locations in the world, (3) the use of a non-hydrostatic model for the atmospheric module which allows an accurate representation of kilometric scale processes. The present article describes the MORCE platform, detailing its various modules and their coupling and illustrating its potential with results obtained in the Mediterranean region and over the Indian Ocean.