Exploring the impact of southern ocean sea ice on the Indian Ocean swells

The present study analyzes the impact of the Southern Ocean (SO) sea ice concentration on the north Indian Ocean (NIO) wave fields through swells using 6 years (2016–2021) of WAVEWATCH III (WWIII) simulations. We did two experimental runs of WWIII, one with sea ice concentration and winds as the forcing (W3(with_ice)) and the second run with only wind forcing (W3(no_ice)). Analysis shows the impact of the SO sea ice concentration on northward swell peaks in September–November, coinciding with the maximum sea ice extent in the Antarctic region of the Indian Ocean. W3(no_ice) simulations are biased more by ~ 60% and ~ 37% in significant wave height and period, respectively, against W3(with_ice) when compared with NIO mooring data. W3(no_ice) simulates low-frequency swells and travels fast towards NIO, with implications for operational oceanography. We have shown that the forecasts of the timing of high swell events along NIO coasts can be erroneous by ~ 12 h if the SO sea ice concentration is not included in the model. Further, W3(no_ice) could potentially produce false swell alerts along southeastern Australian coasts. In summary, our study highlights the importance of the SO sea ice concentration inclusion in the wave models to accurately simulate NIO waves.