Dense shelf water formation process in the Sea of Okhotsk based on an ice‐ocean coupled model

Formation process of the dense shelf water (DSW) in the Sea of Okhotsk was investigated with an ice‐ocean coupled model. The hindcast through 1998–2000 modeled the anomalous ice productions being controlled by air temperature and mean ice speed over the coastal area. Ice production was larger by 30% in 1998–1999, while less developed ice cover in 1999–2000 allowed larger heat loss from the ocean. The compensating heat loss sustained the similar production of the DSW for >26.75 σ θ in 1998–1999. However, ice production thickened up the density constitution of the DSW, which was significantly denser in 1998–1999. An experiment without brine rejection suggested such modification of the density constitution plays a rather more important role in brine rejection for the DSW property than an increase of the volumetric production. The signal of brine rejection reached the 27 σ θ layer farther south in the Kuril Basin. The model also showed that when winter outflow of the DSW from the continental shelf was neglected, as is the case in observational estimations, the annual production was underestimated by 20% compared with actual productions in 1998–2000. Ice production was increased as the air‐ice drag coefficient C Dai increased and as the ice‐water drag coefficient C Diw decreased because of the intensified polynya activity. In contrast, the density constitution of the DSW was lightened with the increased C Dai , as a linear balance of dominantly intensified advection and slight increase of ice production. Consequently, the DSW property seemed insensitive to C Dai and C Diw compared with the anomalous air conditions year by year.