Characteristics of a Madden–Julian Oscillation Event in July 2017 with Numerical Simulations at a Cloud-Permitting Scale

A madden-Julia oscillation event in July 2017 and its interaction with the marine continent (MC) is characterized by numerical simulations at a clod-permitting scale (~3km horizontal resolution) with an advanced research version of Weather Research and Forecasting model.

First, with the NCEP global analysis, GPM precipitation data and CYGNSS ocean surface winds, the anomalies in zonal winds and their association with precipitation and convective propagation have been examined. It is found that the zonal wind convergence became stronger near the marine continent. The MJO system moved Northward without dissipation. However, with coarser temporal and spatial resolution of global analysis, it is difficult to understand how convective systems and MC interact with the MJO evolution.

The high-resolution numerical simulations are thus used to reveal the detailed evolution of mesoscale convective systems, precipitation, local winds (e.g., sea breeze) and diurnal variation of small-scale convection as well as their interaction with the MJO system. The sensitivity of numerical simulations to different microphysical, cumulus, and boundary layer schemes is also conducted to obtain insights on different processes that control the multi-scale interactions. Detailed results will be reported at the conference.