Understanding the Greenland Tip Jet Role in the Future: Declining Surface Heat Loss in a High-Resolution CESM Simulation (2015–99)

The Greenland tip jet is a strong mesoscale westerly wind generated by the effect of Greenland’s steep orography on the Icelandic low. This wind significantly affects air–sea heat fluxes in the Irminger Sea and can intensify deep-water formation, potentially influencing the Atlantic meridional overturning circulation (AMOC). If the frequency or strength of tip jets changes as a result of climate change, this may have important implications for the AMOC. Therefore, we analyzed the possible future of tip jets using a single high-resolution (0.258) Community Earth System Model, version 1.3 (CESM1.3), climate simulation forced with the representative concentration pathway 8.5 (RCP8.5) scenario for 2015–99. We identified tip jet events, estimated the air–sea temperature difference, and composited anomalies of surface heat flux and wind stress associated with tip jet events. We found no significant trends in tip jet frequency or wind stress magnitude under a warming climate. However, we did find a trend in air–sea fluxes, with future ocean heat loss decreasing both during tip jet days and during boreal winter. This decrease is caused by the air–sea temperature difference decreasing as the atmosphere warms faster than the ocean water. Therefore, a decrease in air–sea temperature difference leads to a decrease in background latent and sensible heat loss. Thus, the buoyancy forcing for convection reduces even though there is no significant change in the occurrence of tip jet events. This weakened forcing will contribute to the projected decline in mixed-layer depths as a result of climate change, with likely implications for the AMOC.