Visualization of large-scale internal seiche in Lake Inawashiro

Field observation of water temperature in Lake Inawashiro has been carried out in 1999. Spatial variation of the temperature in the whole area of the lake can be obtained using a simple linear interpolation method, as seen in the figures. In Figs.1 and 2, strong wind from the left caused deepening of the interfacial layer on the right hand side. Subsequently, upwelling of cold water was observed on the left hand side in Figs.3 and 4, followed by the recovery of thermocline in Figs.5 and 6. It should be noted in Fig.6 that the distinct vertical mixing of the lake water occurred after the large-scale oscillation, suggesting that the internal seiche has important role for the change in water quality in the lake.