Laboratory experiments on internal solitary wave reflections and their detectability via water surface infrared thermography

We report on results from laboratory experiments performed in a quasi-two-layer system of cold and warm water in a rectangular laboratory tank. Warm front propagation is initiated by removing a vertical barrier from between the two prepared sections of the tank containing cold and warm water filled up to the same level. The warm front propagation in the vicinity of the free water surface is monitored using a high precision infrared camera from above, and with dye visualisation from the side simultaneously. After the warm front reaches the sidewall of the tank, its "head" is reflected, and hence an internal bore emerges along the interface separating the two layers. Following further reflections the bore splits to a train of internal solitary waves, resembling the solutions of the KdV equation. We find that, interestingly, although the waves propagate along the internal interface, certain surface signatures of the bore and wave dynamics can be detected from the water surface temperature fields due to secondary convective flows. This result may have certain applicability for the detection of internal waves using infrared sea-surface temperature data from satellites.