Abstract
NOAA/National Ocean Service’s (NOS) Center for Operational Oceanographic
Products and Services (CO-OPS) provides users with real-time currents at
more than sixty stations, currents predictions at thousands of historic
and active stations, and operational currents nowcast and near-term
forecast information in navigable estuaries, harbors, rivers, and
coastal regions of the United States as an integral part of its safe
navigation mission. CO-OPS performs at least one current survey each
year to update currents predictions in regions of particular interest to
stakeholders. NOS’ Operational Forecast Systems (OFS) operate and
maintain fully 3-D hydrodynamic models that provide regional nowcast and
forecast (48-60 hours) guidance for water levels, currents, salinity,
and temperature. By combining the information available from real-time
observations, current surveys, historic current predictions, and OFS
output, both the tidal current predictions and the OFS forecast products
can be improved. Tidal current predictions are traditionally generated
based on analysis of at least one month of six-minute observation data
obtained from a physically deployed current meter using harmonic least
squares techniques to resolve tidal constituents. By using longer time
series and traditional techniques combined with additional statistical
methods, a more accurate representation of the tidal flow and a more
exact match to the shape of the tidal current curve is obtained. By
applying these methods to long-term OFS output at locations where
long-term physical observations also exist, tidal current predictions
based on model data within the model domain can be verified. Once
verified, the number of available “virtual stations” exponentially
increases the repository of tidal current predictions. Users can choose
any location of interest and receive tidal current predictions that can
be incorporated into integrated, user-friendly navigation products and
tools. We will evaluate this technique in the lower Chesapeake Bay using
output from the Chesapeake Bay Operational Forecast System (CBOFS) and
real-time currents data.