Projected Changes to Tropical Cyclones in the Southwest Indian Ocean Using High-Resolution Global Climate Models

Tropical Cyclones (TCs) affecting southeastern Africa are poorly understood, due to limited focused research and challenges in modeling TCs. Higher resolution climate models have potential to provide more reliable projections. In this paper, we analyze the latest global high-resolution simulations (“HighResMIP”), to evaluate what these models tell us about current and future TCs in the southwest Indian Ocean. TC tracks are identified by two tracking algorithms in 10 Global Climate Models (GCMs) and we compare to observations and reanalysis. GCMs capture TCs in the same region as observations during the austral summer cyclone season. However, TCs are too weak, not reaching equivalent low pressures to observed storms, but are more intense in high-resolution GCMs (28–55 km) than lower resolution GCMs (≥78 km). We find little improvement in the representation of TCs with increasing resolution, beyond TC intensity. There is no one “best” model for simulating TCs, with notable variations between models in TC climatologies. In experiments of near future climate change (to 2050), there are some consistent signals between models, with nearly all models showing fewer TCs in future. Many models indicate a south-westward shift in TCs. Only the highest resolution model indicates the Lifetime Maximum Intensity of TCs become more intense. All models indicate more favorable oceanic and atmospheric conditions for stronger and more impactful TCs in the Mozambique Channel, including an increase in the Potential Intensity. This study provides an essential benchmark for future research using forthcoming km-scale simulations.