Geographical and monthly variability of the first baroclinic Rossby radius of deformation in the South China Sea

In this paper, based on the 1-degree grided data of the monthly mean temperature and salinity data at standard levels in the South China Sea(SCS), we solve the linearized vertical eigenvalue problem for horizontal large-scale waves, the first baroclinic phase speed c1 and the first baroclinic Rossby radius of deformation R1 are obtained. Due to the regional variations of the water depth, stratification and latitude, R1 varies largely. In most months of a year, in the deep sea area, the effect of temporal variation of the stratification on R1 can be neglected, however, in November and December, R1 in the central SCS changes largely due to a large stratification variation of the local water mass; in the wide continental shelf, the effect of temporal variation of the stratification on R1 is very important. The westward phase speed of the first baroclinic Rossby wave CR1 derived from observations and numerical models give an independent estimation which is consistent with solving the vertical eigenvalue problem, which shows that the estimated CR1 could be used to distinguish and trace the propagation signal of baroclinic Rossby waves in the SCS.