资源环境科技发展态势分析平台

Some basaltic open vent volcanoes show that spectroscopic SO₂ measurements of a volcanic gas plume are characterised by a fluctuating signal. Understanding the origin of these fluctuations is of great interest for interpreting volcanic gas emission regimes. Although some fluctuations may be associated with intermittency in the source flux, some may be associated with the turbulence in the flow. A simple laboratory experiment, in which we release dye pulses into a turbulent wake in a small water‐filled channel, suggests that when the intermittency of the source has comparable or smaller time scale as the turbulence, the fluctuations are similar, whereas when the intermittency of the source has longer time‐scale than the turbulence, the fluctuations can be distinguished. We also present some small‐scale laboratory experiments of turbulent buoyant plumes produced from a steady source; these demonstrate a time‐fluctuating concentration of source fluid downstream and the fluctuations tends to increase with distance.

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