Convection-permitting simulations of diurnally forced convection over the Maritime Continent

The Maritime Continent region is characterised by a variety of convective systems, ranging from locally forced systems with a strong diurnal cycle though to large-scale propagating systems like the MJO. The locally forced systems can arise due to land and sea breeze circulations, orographic uplift, and other geographically forced circulations like gravity waves. Most of these processes occur on the mesoscale and are therefore poorly resolved by all but the highest resolution models. Indeed, it is well known that models with parameterized convection have difficulty simulating the diurnal cycle of convection in the maritime continent and unresolved mesoscale processes are one likely reason.

In this study we use convection-permitting simulations of the maritime continent region to investigate the important processes governing the diurnal cycle of convection. Simulations are conducted over a period of suppressed large-scale forcing within the ‘Year of Tropical Convection' (YOTC); a suppressed period is chosen to maximise the diurnal influence. Simulations are conducted with the Weather Research and Forecasting (WRF) model as well as the UK Met Office's Unified Model, with initial and boundary forcing provided by the YOTC high-resolution ECMWF analysis data. Preliminary comparisons between the two models, different model resolutions, and the available observations will be presented.