CODAR Real time vector fields: standard

CODAR is used to measure the surface currents of the coastal ocean. A
transmitter sends out a radio frequency that bounces off the ocean
surface and back to a receiver antenna. Using this information and the
principles of the Doppler shift, CODAR is able to calculate the speed
and direction of the surface current. These calculations are made at
about every half mile across the surface and extend as far as about
twenty miles offshore.

The following Data is available online:

Raw Vector Field: The raw surface current is the unprocessed data
measured by CODAR. Therefore these velocity fields are the summation
of all sources of current, including tides and wind.

Tidal Vector Field: This vector field represents the component of the
raw velocity that is caused by tidal forcing.

Detided Vector Field: The detided vector field contains all the
surface currents shown in the raw velocity field with the exception of
the tidal currents. Using the above periods, a predicted tide is
calculated and then subtracted from the raw data field.

Low-pass Vector Field: The low-pass surface current field is
representative of the second step of data processing. A low-pass
filter is applied to the detided data to further eliminate any other
currents with a period less than 30 hours. The data is delayed three
hours because the filter needs information up to three hours after the
time of calculation.

High-pass Vector Field: These high frequency currents are calculated by
subtracting the low-pass field from the detided field. Therefore,
These currents have periods less than thirty hours and do not include
the tides.