QPE Pilot Study Ocean Physics Forecast

Forecast for 7 September 2008, Issued 5 September 2008

This web page presents the output from two 7 day free surface simulations forced with a combination of COAMPS (wind stress) and NOGAPS (heat-flux, E-P) atmospheric forcing, initialized using the Taiwanese in situ data and a summer climatology created using June-August profiles and the HydroBase2 software. The bathymetry used is the NCOR bathymetry.

In our simulations so far, the biggest uncertainty remains the transport just north of Taiwan, in part driven by the transport in the Taiwan Strait between Taiwan and mainland China. To illustrate this point, we decided to issue 2 forecasts, one with an initial 1Sv northward transport and one with a (freely-computed) initial 2.5 Sv southward transport through the Strait. Of course, these boundary transports change with time, based on the interior flows and open boundary conditions.

From the OR2 and OR3 data we have from last week, from the SST data and from our varied model simulations which assimilate the OR2-OR3, we believe there is some upwelling of deeper Kuroshio water on the shelf just north of Taiwan, with nice filaments being advected north-eastward along the shelfbreak on the edge of the Kuroshio (this seems to match the older SST analyses from the Taiwan Central Weather Bureau). This would indicate that currents just north of Taiwan are westward. Associated with this is a relatively classic situation of a meander of the Kuroshio in the QPE area (which appears in this run with a westward flow just north of Taiwan). In summary, this means that the "Free initial Transport" model forecast should be closer to the truth. However, we are not yet certain; more study is needed. In particular, this westward flow is likely too strong in our "free initial transport" simulations.

As a note, the above preliminary analysis would indicate that there is no cyclonic eddy above the QPE area. This eddy is created in the run with an eastward flow just north of Taiwan. In the "Free initial transport run", it is replaced by a meander of the Kuroshio.

Acoustic simulations from each of these two dynamical simulations, with vertical sections of transmission loss (TL) and sound speed, can be found here.

Nowcasts and Forecasts of Environmental Conditions
Initial Transport 50m Temperature 50m Salinity 50m Velocity Complete set of Plots
Nowcast - 6 September Forecast - 7 September Nowcast - 6 September Forecast - 7 September Nowcast - 6 September Forecast - 7 September
2.5Sv S X
1.0Sv N X

Available NetCDF Files
2.5Sv S Along Grid peout_free05sep2008.nc.gz
Geographic peout_geo_free05sep2008.nc.gz
1.0Sv N Along Grid peout_fix05sep2008.nc.gz
Geographic peout_geo_fix05sep2008.nc.gz