Bottom currents induced by baroclinic forcing in Lake Banyoles (Spain)

Because of the difference in morphometry and in the underground heating of the two lobes of Lake Banyoles there is a differential cooling that causes a density current - the denser water of the shallower lobe plunging into the deepest lobe forming a bottom current - which redistributes water between the lobes and replaces that of the northern lobe about every 5 days. This current has been studied during the mixing periods of the years 1989-1991 from temperature and current measurements and it has been found that it increases or slows down depending on the direction of the wind. Furthermore, it is observed that it mainly flows along the west shore of the lake, deflecting towards the right as an effect of the bottom morphometry. However, due to the long time scale of the density current the influence of the earth's rotation should not be neglected in advance. Finally, a simple numerical model has been used to corroborate the magnitude of this current - whose velocity has been directly measured - which is found to be the most important in the lake during the mixing period and so, it dominates the lake-wide circulation © 1993 Birkhäuser Verlag.