Greenland Tip Jet in the future: Declining Surface Heat Loss in a High-Resolution CESM Simulation (2015-2099)

Abstract

The Greenland Tip Jet is a strong westerly wind generated by the interaction between the synoptic Icelandic Low and the steep Greenland orography. Tip Jets were not extensively explored until the beginning of 2000s when gridded atmospheric products reached temporal and spatial resolution high enough to resolve such mesoscale wind events. This mesoscale wind affects surface heat and freshwater content in the area to the southeast of Greenland and then it causes intensification of deep water formation in the Irminger Sea. Through this increase in deep convection intensity, Tip Jets can potentially affect the large scale Atlantic Meridional Overturning Circulation (AMOC) transport on daily-centennial time scales. Given Tip Jets’ role in deep convection, the research question arises: Will the influence of Tip Jets on AMOC change in the future? In the current research, we aim to fill the gap on the Tip Jet variability in the 21st century using the high resolution (0.25°) CESM 1.3 future climate simulation forced with RCP 8.5 for 2015-2099. We identify Tip Jets, estimate future composite anomalies of the surface heat flux and wind stress associated with Tip Jet events, and define the leading factors of their variability in the 21st century. Our analysis reveals no significant trends in Tip Jet frequency or wind stress for 2015-2099. Although no long-term changes are modelled in Tip Jets and wind stress, upward surface heat flux decreases both during Tip Jet days and during the whole winter season (DJFM) in the area to the southeast of Greenland. We attribute this decrease in surface cooling to changes in air-sea temperature difference (Ta – SST). To the east of Cape Farewell, the atmosphere is warming faster than water, causing Ta – SST to shrink during the 21st century. The observed trend in Ta – SST subsequently appears in surface latent and sensible heat fluxes growth for 2015-2099. Therefore, the more rapid warming of the atmosphere compared to the ocean leads to an increase in background latent and sensible heat, resulting in less cold being transported to the central Irminger Sea during Tip Jets. We showed that Tip Jets will likely continue to affect heat and freshwater content in the Irminger sea, however, the character of this influence will be different with climate change during the 21st century.