Coastal Ocean Dynamics Applications Radar (CODAR)
Real-Time Data

Raw Vector Field

The raw surface current is the unprocessed data measured by CODAR. Therefore the following vector plot is the summation of all sources of current, including tides and wind.

Tidal Vector Field

The Tidal vector field represents the currents that are subtracted from the raw data to get the detided current fields. In this step, local tidal currents are subtracted from the raw data. The following tidal constituents were used to calculate the tidal currents:

• Half a Lunar Day (Period = 12.42 Hours)
• Half a Solar Day (Period = 12.00 Hours)
• A Lunar Day (Period = 25.82 Hours)
• Luni-Solar (Period = 23.93 Hours)
• Larger Lunar Elliptic (Period = 12.66 Hours)

Using the above periods, a predicted tide is determined and plotted.

Detided Vector Field

The detided vector field represents the first step of data processing. In this step, local tidal currents are subtracted from the raw data. These local currents are calculated by getting a least squares fit to regional tidal oscillations. The following tidal constituents were used in the processing:

• Half a Lunar Day (Period = 12.42 Hours)
• Half a Solar Day (Period = 12.00 Hours)
• A Lunar Day (Period = 25.82 Hours)
• Luni-Solar (Period = 23.93 Hours)
• Larger Lunar Elliptic (Period = 12.66 Hours)

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 short frequency currents. The data is delayed three hours because the filter needs information up to three hours after the time of calculation.

High-pass Vector Field

The short frequency currents are calculted by subrtacting the low-pass field from the detided field.

Surface Divergence

The surface divergence is calculated based on the low-pass current field. It is a measure of if water motion toward or away from a particular point on the ocean surface. Positive values represent water being forced away and negative values represent water forced toward the surface point.

Surface Vorticity

The following surface vorticity plot is calculated based on the low-pass current field. Surface vorticity is a measure of the "spin" of a partical about its axis. Counterclockwise rotation is positive and clockwise rotation is negative.