Laboratory studies of interleaving

This is a review of laboratory experiments on double-diffusive interleaving. Several configurations are discussed and compared, including thermohaline fronts, heated sidewalls, melting ice-blocks, point heat sources, and double-diffusive plumes, using both the heat-salt and sugar-salt systems to generate property anomalies. Two parallels emerge. The vertical scale of intrusions in most configurations is proportional to the ‘natural’ scale given by the property anomaly divided by the density gradient. The speed of advance of intrusions into undisturbed water is proportional to the product of the buoyancy frequency and intrusion thickness, with a constant of proportionality of order 0.005, but which depends on the vertical gradient density ratio and on the experimental configuration.We end with a long list of questions. Further progress will require new or more complex experimental configurations, more quantitative observations, and close comparisons with intrusion theories, both linear and finite-amplitude.