资源环境科技发展态势分析平台

Motivated by potential effects of the Earth's rotation on the Deepwater Horizon oil plume, we conducted laboratory experiments on saltwater point plumes in a homogeneous rotating environment across a wide range of Rossby numbers 0.02 <= Ro <= 1.3. We report a striking physical instability in the plume dynamics near the source: after approximately one rotation period, the plume tilts laterally and starts to precess anticyclonically. The mean precession frequency.. (omega) over bar scales linearly with the rotation rate Omega as.. (omega) over bar approximate to 0.4 Omega. We find no evidence of a critical Rossby number above which precession ceases. We infer that a conventionally defined Rossby number is not an appropriate parameter when the plume is maintained over a long time: provided Omega not equal 0, rotation is always important to the dynamics. This indicates that precession may occur in persistent oceanic or atmospheric plumes even at low latitudes.