Numerical modeling of upwelling filaments using ROMS

Edith Soosaar
Tallinn University of Tecnology, Estonia


Upwelling filaments cause offshore export of cold nutrient-rich water. Coastal upwelling and upwelling filaments are common phenomenon in the Gulf of Finland (GOF). Observations show that locations of upwelling centers and filaments are very often highly repeatable.
The Regional Ocean Modeling System (ROMS) is used to model coastal upwelling filaments in short time period (10 days). To gain overview of upwelling filaments formation we consider three high resolution (2.7 km) experiments in the GOF area. In the first two experiments, the model is forced with constant wind from west and east cardinal points, while third experiment is with measured wind from 19 July 1999 to 29 July 1999 when upwelling filaments were observed in GOF. Measured water temperature and salinity profiles (horizontally constant) were used for all three experiments.
In first two experiments upwelling started to occur with one and half day and clear defined filaments emerged between the third and forth day. Anticyclonic eddies, which curved filaments in their rotating direction, developed on the right side of the filaments in the both cases. For the end of simulation upwelling was covering entire coast and had spread cross-shore to the half of the GOF. Filaments extended to the opposite coast. More pronounced filaments had started to form mushroom head shape.
Comparison of third experiment and observations, show good agreement in the location of filaments, but strength and offshore extent was underestimated in the model. The major difference between simulated and observed filaments was that the modeled filaments tend to curve clockwise while the observed filaments tend to curve counterclockwise.