ALBERT

Description: Precipitation in the tropics is dominated by variability on seasonal, intraseasonal and diurnal scales. However, at the finest spatial scales, this variability can be strongly modulated by numerous local factors that represent a range of physical processes. One aspect of this modulation that operates across multiple scales is the orientation of coastal and inland topography relative to the background wind. This is particularly relevant where complex topography occurs in the vicinity of tropical coastlines, which can cause local changes in moisture flux convergence. Another aspect is the coupling of the diurnal cycle to changes in surface heating, surface moisture, column moisture, background wind and cloudiness. This link between clouds, radiation and diurnally forced convection forges a two-way interaction between the intraseasonal scales and mesoscale variability. Further to these modulating factors, propagating disturbances from neighbouring coastlines, and interactions between coastal processes across adjacent seas introduces a non-local mesoscale source of variability, particularly amidst the complex archipelago of the Maritime Continent. These processes also occur outside the deep tropics, where the added complexity of mid-latitude interactions contributes to the overall variation in precipitation. Multiple spatial and temporal scales are impacted by these competing sources of variability, which presents a challenge in quantifying their representation and impact in weather and climate models. This has implications for weather prediction and down-scaling of climate change projections. This talk will examine some of the local manifestations of scale-interactions in tropical Queensland (Australia) and the Maritime Continent, using diverse observational datasets and high-resolution numerical modelling.