Strengthened Linkage Between July and August Beaufort Sea Ice and August Precipitation in Southern Greenland Since 2008

ABSTRACT This study investigated the interannual relationship between July and August Beaufort Sea ice (BSIC) and August southern Greenland precipitation (SGP). Additionally, underlying mechanisms were explored using the ECHAM5 model. During 2008–2023, the interannual correlation between July and August BSIC and August SGP increased significantly compared to 1990–2007, with correlation coefficients of 0.70 and 0.51 for two precipitation datasets, both passing the significance test at the 95% confidence level. Further analysis indicated that, after 2008, the BSIC decreased significantly. The proportion of first‐year ice increased, while sea ice thickness declined. These changes contributed to enhancing interannual variability in sea ice and strengthened the interannual correlation between BSIC and SGP. In terms of the mechanism, when BSIC decreased, it was accompanied by rising sea–air temperature and specific humidity differences. The upward sensible and latent heat fluxes increased. The reduction in sea ice triggered eastward‐propagating Rossby waves, causing circulation anomalies in the North Atlantic resembling a negative phase of the summer North Atlantic Oscillation. Such circulation patterns inhibited moisture transport from the southwestern direction of the Labrador Sea and enhanced subsidence through cold advection, leading to reduced SGP. Conversely, when BSIC increased, the opposite effect occurs. Since 2008, the significant interdecadal decline in BSIC has become a key driver of the interdecadal decrease in SGP, although the latter is also influenced by the complex interactions within the climate system. Simulations using the ECHAM5 model confirmed these possible physical mechanisms behind the relationship.