Future Changes in the Impact of North Pacific Midlatitude Oceanic Frontal Intensity on the Wintertime Storm Track in CMIP5 Models

The storm track and oceanic front play an important role in the midlatitude air–sea interaction. In this study, future changes in the impact of the North Pacific midlatitude oceanic frontal intensity on the wintertime storm track are projected based on climate model outputs from the Coupled Model Intercomparison Project Phase 5 (CMIP5). The performance of 13 CMIP5 models is evaluated, and it is found that a majority of these models are capable of reproducing the northward intensification of the storm track in response to the strengthened oceanic front. The ensemble means of outputs from six best models under three Representative Concentration Pathway (RCP) scenarios (RCP2.6, RCP4.5, and RCP8.5) are compared with the results of the historical simulation, and future changes are projected. It is found that the impact of the oceanic frontal intensity on the storm track tends to get stronger and extends further westward in a warming climate, and the largest increase appears in the RCP8.5 run. Further analysis reveals that the stronger impact of the oceanic front on the storm track in the future may be partially attributed to the greater oceanic frontal impact on the near-surface baroclinicity, which is mainly related to the intensified oceanic frontal impact on the meridional potential temperature gradient under the climate change scenario. However, this process can hardly explain the increasing impact of the oceanic front on the upstream of the storm track.