Frontal wave development over the Southern Ocean.

摘要

The development of frontal waves over the Southern Ocean is described using SeaWinds-on-QuikSCAT scatterometer surface winds. A planetary boundary layer model is used to construct surface pressure fields and correct the wind errors due to rain contamination and the geometry of the scatterometer antenna. The divergence and vorticity are calculated from the winds and used to diagnose frontal wave development over the Southern Ocean.; Three fronts are examined. An attribution technique is used to partition the wind field in nondivergent and irrotational components at the scale of the front and the remaining harmonic component (or environmental flow) induced by the synoptic scale flow. The front and the environment in which the front is embedded can be analyzed separately.; It is shown that frontal waves develop when the large-scale along-front stretching decreases and the environmental flow becomes frontolytic. Three of the observed frontal waves deepen into secondary cyclones. A connection with the upper-levels is observed in each case. The last frontal wave is not in a favorable configuration with the upper-levels and does not deepen significantly.