Mixed layer deepening and variability in the upperlayers if the central western Mediterranean, MILEX-82: final report

Abstract

The 1982 Mixed-Layer Experiment (MILEX-82) is described in detail and the data are presented in ways designed to illustrate the spatial and temporal variability of the surface and deeper layers of the central western Mediterranean during the autumn transition period. The surface mixed-layer is seen to cool and to deepen due to convection and mechanical stirring induced by passing storms. The predominating motions observed, and the ones given most attention in this report, are the near inertial internal waves propagating horizontally and vertically from the mixed layer into the pycnocline. Possible generation mechanisms for the vertical oscillations are discussed. It is argued that these may originate well to the north of the study area in the Golfe du Lion, where a high amplitude, inertially oscillating, Ekman mass-flux divergence can be expected due to the high values of windstress curl in that region. Data are, in some cases, fairly extensively 'worked up' to produce a variety of contour plots for temperature, salinity, density and dynamic anomaly and a variety of composite time-series for both the thermistor-chain data and current-meter array vectors. Also presented, but discussed in less detail, are a number of measured and derived quantities relevant to air-sea interaction and mixed layer deepening. It is considered that these will be useful for comparison with other, similar experiments and with output from numerical models.