AN EXPERIMENTAL INVESTIGATION ON TOPOGRAPHIC EFFECT ON MULTIPLE REGIMES OF BAROCLINIC FLOW

A rotating annulus experiment is used to study the large scale motion in the thermally-driven baroclinic fluid in the presence of a two ridge sinusoidal topography around the annu-lus. The fundamental effect the topography exerts on the large scale motion in the baroclinicfluid is to modulate the flow and thus to make the flow uneven both in time and in space.The most important paramenter which dominates the flow regime in the fluid is the Rossbynumber. When the imposed Rossby number is very small （R≤0.06） or the imposed tem-perature difference between the walls of the annulus is very small （△T<0.5℃） the flowpattern is wave-like steady flow. When the Rossby number increases （0.06≤R≤0.2） theflow pattern becomes travelling waves with strong vacillation due to the topographic effect.The flow possesses at least two primary regimes, one is zonal regime and the other is meri-dional. The vacillation weakens with increasing Rossby number. When the Rossby numberis large or very large （R≥2.0） the fast