D7.1: Report on simulating tropical climate and its variability and teleconnections Deliverable number D35 (Del. Rel.

About this document This report provides the assessment of the importance of resolving air-sea interactions on mesoand sub-mesoscales for simulating tropical climate, including its major modes of sub-seasonal to seasonal variability and the West African Monsoon, as well as for simulating climate change. Work package in charge: WP7 Executive summary This deliverable reports on the simulation of climate and, especially climate variability and change in the tropics by NextGEMS models. On the one hand, we have addressed the representation of mean climate and its variability in the models by comparing with observation-based products to investigate the importance of resolving air-sea interactions on km-scales for climate. On the other, we have used the simulations to explored scientific questions like projected changes in the climate system or the role of the background state in shaping teleconnections. For this two-fold purpose, we have mainly focused on multi-decadal NextGEMS simulations spanning cycles 2 to 4. We have addressed the simulation of air-sea coupled modes of variabilitysuch as the Pacific and the Atlantic Niño, their teleconnections and interactions. We have detailed the simulation of ocean upwelling regions and subtropical regions with strong presence of stratocumulus cloud decks. Finally, tropical rainfall and particularly monsoon systems have been investigated and related to the simulation of energy transports in the atmosphere and to the representation of synoptic-scale phenomena.