Forecast 08/28

The casts done by the 3 boats in the north channel are very interesting, and the model-data comparisons revealed that the ocean forecast is frequently better than even the DA forecast, for salinity profiles ( DA vs. ocean forecast) and flow-thru ( DA vs. ocean forecast), and temperature flow-thru (DA vs. ocean forecast). This is due to the different transport algorithms used in the two forecast; in particular, the mass-conservative upwind scheme seems to lead to better results, although the salinity values around mid-estuary (am169) continue to be under-estimated by this algorithm. The comparisons indicate that if this difficulty can be resolved, the ocean forecast will the preferred forecast everywhere (and we can cut down the total number of forecasts).

The plume tomorrow will likely be under upwelling wind most of the time. The discharge is near minimum. Therefore the plume extent is not expected to be very large.