Very high-resolution climate modelling for rain and wind
Heavy rainfall and extreme winds are increasingly impacting communities in New Zealand, and as they occur on such local scales, traditional atmospheric models struggle to represent these weather processes.
New Zealand weather systems are strongly influenced by the Southern Alps, where coarse model resolution can result in rainfall being simulated in the wrong river catchments. Very high-resolution modelling is refining our understanding of these weather processes, and will contribute to improved projections of New Zealand’s future climate.
This project has developed very-high resolution modelling capability (2.2 km), and is focussing its analysis on key weather processes in NZ that occur on small spatial scales, such as rainfall triggered by moisture-laden air being forced over mountain ranges, extreme winds and intense low-pressure systems.
- A regional climate model has been configured for New Zealand at a 2.2 km grid spacing, allowing the complex mountainous terrain of New Zealand to be better represented. Analysing historical simulations, the model shows improvement in the representation of important weather phenomena such as intense short-duration rainfall.
- The New Zealand Earth System Model (NZESM) has been successfully downscaled to 2.2km over NZ in a multi-year simulation (beginning in 2080) under a high-emissions warming scenario (SSP3-7.0).
How this research is being used:
- Very high-resolution climate simulations are providing new insight into the behaviours of rainfall, snow and wind in New Zealand, particularly in alpine regions, and how these may change under future warming caused by increased greenhouse gases.
- This modelling will ultimately be used to improve future projections of a range of downstream environmental processes including river flows and flooding.