Joint Seminar: Explicit versus Parameterized Convection in Response to the Atlantic Meridional Mode

This study investigates whether the representation of explicit and parameterized convection influences the response to the Atlantic Meridional Mode (AMM). The AMM is an important mode of variability in the tropical Atlantic characterized by a meridional dipole of SST anomalies coupled to cross-equatorial low level winds. As a consequence, the position of the Intertropical Convergence Zone is displaced towards the warmer hemisphere.  Despite the increased use of storm-resolving simulations, the response and coupling of explicit convection to modes of SST variability, such as the AMM, has not been previously studied. In this talk we focus on two questions: i) Is the precipitation response to the AMM different in simulations with explicit convection and with parameterised convection? and ii) does the explicit representation of convection lead to a different coupling of convection and SST? The results show that the precipitation response can be interpreted as a meridional shift of 1° in the precipitation climatology for uncoupled simulations with explicit and with parameterized convection. Moreover, slab-ocean simulations reveal that the dissipation of SST anomalies are more pronounced with explicit than parameterized convection. This change in SST is between 0.5K-1K colder for simulations with explicit convection and it is partly explained by stronger wind-induced surface fluxes.

Date

01.06.2021

Time

15:15 h

Place

Virtual Seminar
Hamburg

Speaker

Laura Paccini

Organizers

Diego Jiménez-de-la-Cuesta Otero

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