Impacts of high-resolution atmospheric forcing and air-sea coupling on coastal ocean circulation off the Pearl River Estuary

Abstract

We investigated the impacts of high-resolution atmospheric forcing and ocean-atmosphere coupling on the estuary-shelf ocean simulation off the Pearl River Estuary. We conducted process and dynamics analyses of the wind-driven coastal ocean circulation under atmospheric flux forcing from (1) global reanalysis data, (2) a high-resolution regional atmospheric model, and (3) an air-sea coupled model during an upwelling-favorable wind. The results revealed that the high-resolution atmospheric model significantly improved the representations of the near-surface wind field and air temperature. The air-sea coupled model outperformed the uncoupled model in simulating coastal currents, water temperature, and salinity. The high-resolution uncoupled model strengthened the surface wind stress and along-isobath pressure gradient force (PGF), resulting in an intensified cross-isobath transport. The improved wind forcing from the air-sea coupled model modulated the spatial variation of the net stress curl and vorticity advection and enhanced the along-isobath PGF for a stronger cross-isobath transport. The lower sea surface temperature (SST) in the air-sea coupled model reduced the air temperature and wind stress. Adjusting the SST in the air-sea coupled model improved the momentum fluxes and the associated ocean transport dynamics.