The upper ocean hydrography of the central Arctic Ocean, encompassing the mixed layer and the halocline layer, plays a fundamental role in mediating ocean-ice-atmosphere interactions and isolating surface sea ice from underlying warm water masses. Over the past two decades, this region has undergone profound transformations driven by amplified climate change. By synthesizing extensive in-situ observational profiles and ocean reanalysis data during 2000-2023, we identify distinct regional divergences in hydrographic evolution. We further explore the physical mechanisms driving these variations, highlighting the competing influences of atmospheric wind forcing, sea ice thermodynamic processes, lateral advection and their responses to the shifting circulation regime. Our findings emphasize the complex interplay between vertical convective processes and lateral advection in modulating Arctic stratification, carrying critical implications for future sea-ice evolution and diapycnal heat fluxes in a rapidly warming Arctic.