The residual flow in the inlets of the Venice lagoon subject to bora and sirocco winds has been studied. Current velocities have been monitored since 2001 using Acoustic Doppler Current Profilers (ADCP) installed on the beds of the inlets that connect the lagoon to the Adriatic Sea; these inlets are the Lido, Malamocco and Chioggia. Wind velocity data have also been continuously measured at an oceanographic platform 14.8 km offshore from the lagoon. These data were subsequently decomposed into Principal Components, which are associated with bora and sirocco wind directions. Analyses show that the inflow in the Lido inlet is strongly related to the bora wind. The outflow at the Chioggia inlet occurs during bora events, but shows a slightly weaker correlation with the wind speed, while Malamocco inlet shows little or no influence of bora winds on flow patterns. A net residual inflow through the Lido and Malamocco inlets was found, while outflow prevails in the Chioggia inlet. During bora events, the average residual inflow increased three-fold at the Lido inlet, whereas the outflow at the Chioggia inlet doubled. The current velocities at the Lido and Chioggia inlets are best described by an exponential function of wind velocity with exponents of -0.1187 and -0.0924, respectively. The response to sirocco events was evident mainly at the Chioggia inlet. Specifically, there was a slow down of the outflow in linear proportion to wind speed. In excess of 10 m/s a complete current reversal was observed. Lido and Malamocco inlets showed little or no response to sirocco winds, except during rare cases when wind speeds exceeded 15m/s.
The effect of wind on the residual current velocities in the inlets of Venice lagoon
Mazzoldi A
2010
Abstract
The residual flow in the inlets of the Venice lagoon subject to bora and sirocco winds has been studied. Current velocities have been monitored since 2001 using Acoustic Doppler Current Profilers (ADCP) installed on the beds of the inlets that connect the lagoon to the Adriatic Sea; these inlets are the Lido, Malamocco and Chioggia. Wind velocity data have also been continuously measured at an oceanographic platform 14.8 km offshore from the lagoon. These data were subsequently decomposed into Principal Components, which are associated with bora and sirocco wind directions. Analyses show that the inflow in the Lido inlet is strongly related to the bora wind. The outflow at the Chioggia inlet occurs during bora events, but shows a slightly weaker correlation with the wind speed, while Malamocco inlet shows little or no influence of bora winds on flow patterns. A net residual inflow through the Lido and Malamocco inlets was found, while outflow prevails in the Chioggia inlet. During bora events, the average residual inflow increased three-fold at the Lido inlet, whereas the outflow at the Chioggia inlet doubled. The current velocities at the Lido and Chioggia inlets are best described by an exponential function of wind velocity with exponents of -0.1187 and -0.0924, respectively. The response to sirocco events was evident mainly at the Chioggia inlet. Specifically, there was a slow down of the outflow in linear proportion to wind speed. In excess of 10 m/s a complete current reversal was observed. Lido and Malamocco inlets showed little or no response to sirocco winds, except during rare cases when wind speeds exceeded 15m/s.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
