Impacts of Transition From Pack Ice Zone to Marginal Ice Zone in the Arctic Ocean on Heat Exchanges Within the Atmosphere‐Sea Ice‐Ocean System

Abstract With the rapid loss of Arctic sea ice in recent decades, the pack ice zone (PIZ) is gradually transitioning to the marginal ice zone (MIZ), but its impacts on heat exchanges within the atmosphere‐sea ice‐ocean system remain unquantified. This study identifies the transition region from PIZ to MIZ using a positive difference in MIZ occurrence frequency between 1979–2010 and 1992–2023, and compares changes in heat exchanges in this region to those over the pan Arctic Ocean. The transition from PIZ to MIZ in summer increases shortwave radiation absorption by the ice‐ocean surface (0.7 W m −2 yr −1 , P < 0.05), further increasing upper ocean heat content (0.04 × 10 8 J m −2 yr −1 , P < 0.05); while that in winter enhances the exchanges of longwave radiation (about 0.8 W m −2 yr −1 , P < 0.05) and surface upward latent and sensible heat fluxes (0.4 and 0.5 W m −2 yr −1 , P < 0.05), partly leading to an increase in 2‐m air temperature (about 0.2 K yr −1 , P < 0.05), more than twice the average of the pan Arctic Ocean, although the transition region occupies less than 25% of the pan Arctic Ocean. The amplification of heat exchanges is more pronounced in the transition region from PIZ to MIZ than in the MIZ defined by ice concentration between 15% and 80%. Results highlight that the transition process from PIZ to MIZ is more critical for the thermodynamic coupling of the Arctic atmosphere‐sea ice‐ocean system, compared to changes in the location and extent of MIZ.