Evolution study of the Qingdao Cold Water Mass

Abstract The Qingdao Cold Water Mass (QCWM), located in the offshore waters near the Shandong Peninsula, exhibits notable seasonal variability and plays a crucial role in shaping hydrological conditions due to its distinct temperature and salinity structures. This study investigates the evolution of the QCWM in 2014 using cruise observations and the hydrodynamic model FVCOM. Results reveal that the QCWM forms in April and dissipates by June. Momentum analysis indicates that its springtime formation and persistence are facilitated by an anticyclonic circulation and the weakness of the pressure gradient force. In summer, the emergence of the Yellow Sea Cold Water Mass (YSCWM), combined with the frontal circulation at its edges, enhances the westward baroclinic pressure gradient force and destabilizes the structure of the QCWM. Lagrangian particle tracking experiments suggest that the bottom water of the QCWM primarily originates from local cold waters off the southeastern coast of the Shandong Peninsula in winter and dissipates locally in summer. The QCWM’s persistence in the absence of tidal signals underscores its localized characteristics.