NOAA conducts current surveys to gain critical understanding of tidal currents so commercial and recreational mariners can navigate safely. In order to provide the most accurate predictions possible, NOAA must periodically resurvey various coastal and estuarine locations. Survey locations are selected based on mariners’ navigation needs, oceanographic analyses, and the amount of time that has passed since the last survey. Given modern improvements in measurement and computing technology, these surveys greatly improve the accuracy of tidal predictions.
How does NOAA measure the currents?
Currents are the horizontal movement of water from one location to another. They’re observed throughout the water column for a period of months with sensors that also collect pressure, temperature, an salinity data during deployment. Upon retrieval, oceanographers conduct a mathematical process called harmonic analysis to determine which part of the observed current is derived from tides (due to the gravitational attraction to the sun and moon) and which are from non-tidal forces, such as from the wind or freshwater runoff from rain. Future trajectory of the sun and moon are known, allowing tidal currents to be predicted for years to come.
Updating the New York Harbor Tidal Currents
NOAA recently concluded its Current Survey for New York Harbor. Tidal current predictions have ensured safe navigation of local waterways in this area since the middle of last century, back to 1855 in some locations. NOAA engaged regional partners to pin-point the best location for each instrument, and in 2019, deployed 36 temporary instruments in New York Harbor to assess tidal currents from the Hudson River to Sandy Hook Bay. Data collected are not only analyzed to update tidal current predictions, but also support NOAA’s Operational Forecast System (OFS) hydrodynamic models and Precision Navigation efforts; safeguarding navigation of New York Harbor ports and waterways into the future. Updated information will be available to mariners in the summer of 2020. All tidal current predictions can be accessed here.
READ MORE at tidesandcurrents.noaa.gov