Internal undular surges in Seneca Lake: A natural occurrence of solitons

A thermistor array was monitored at barge sites in Seneca Lake for four seasons. During summer and fall when the lake is well stratified internal surges are often observed traveling from south to north. The isotherms are as much as 20 meters deeper after the surge, which travels at a speed of 35 to 40 cm/sec. A wave train with two distinctive parts characterizes these surges. First there are a number of spatially coherent pulses with broad peaks and sharp troughs that are followed by a lower-amplitude wave train that is less coherent. The initial pulses are interpreted as the solitons of nonlinear wave theory. The trailing waves are the oscillatory tail also predicted by theory. Recent results by others have elucidated the generation and propagation of waves that have large amplitudes but that do not break. The numerical calculations for these waves explain aspects of the internal surges in Seneca Lake.