Topics:
Boualem KHOUIDER (U. Victoria, Canada)
"Stochastic lattice systems for climate models"
Abstract:Tropical weather and climate variability consists of numerous circulation and cloud systems that occur on a hierarchy of temporal and spatial scales ranging from the scale of the convective cloud of 1km to 10 km to planetary intraseasonal disturbances such as the Madden Julian oscillation (MJO) and monsoon dynamics. These systems interact nontrivially with each other and with the global dynamics. Unfortunately, despite most recent improvements, state-of-the-art climate models represent very poorly these systems and their mutual interactions and their interactions with global dynamics as well as the rainfall distributions in the tropics. The representation of clouds and rainfall variability in the tropics is still one of the major uncertainties in the climate models used for the IPCC climate projections. The culprit is believed to be the poor representation of clouds and organized convection by the underlying subgrid models used to represent convection and clouds, which are deterministic in nature, are based on the quasi-equilibrium theory, and as such fail to represent the often chaotic variability due to the interactions of various cloud types with each other and with the environment. Instead, we use a stochastic lattice interacting particle system to represents these clouds and associated interactions using observations as a guiding principle. This leads to a better representation of the afore mentioned tropical modes of variability including the MJO and monsoon dynamics.
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