The Coastal Data Information Program (CDIP)

The Coastal Data Information Program (CDIP) is operated by the Ocean Engineering Research Group
(OERG) of the Center for Coastal Studies (CCS) at the Scripps Institution of Oceanography (SIO). Its
offices are located in Isaacs Hall at SIO. CDIP measures, analyzes, archives, and disseminates coastal
environment data for use by coastal engineers, planners, and managers as well as scientists and
mariners. 

With seed money from the California Sea Grant Program, Dr. Richard J. Seymour and the OERG staff
developed a wave data collection system which could be accessed remotely by normal telephone lines.
In 1975, Dr. Seymour began what is now called CDIP with a single wave measurement station at
Imperial Beach, California, with funding from the California Department of Boating and Waterways
(CDBW). In 1977 the U.S. Army Corps of Engineers began funding CDIP in partnership with CDBW
and now provides the major share of the program's operating budget. 

Under the management of David Castel, the CDIP network has grown steadily over the years. It has
deployed and maintained wave (and occasionally wind and current) gauging stations at over 100
locations along the coasts of California, Oregon, Washington, Hawaii, Georgia, Minnesota, Virginia and
North Carolina. Waves are measured offshore in deep water using buoys or pressure sensors attached to
oil drilling platforms. This includes nondirectional buoys which measure wave energy and, increasingly,
directional buoys which also measure some basic directional properties of the wave field, such as mean
wave direction and directional spread, as a function of wave frequency or period. Since 1999, the CDIP
data acquisition platform is a Sun Microsystems workstation. 

Close to shore, in water depths of 30 to 60 feet, waves are measured using pressure sensors mounted
near the bottom. These instruments measure pressure fluctuations, or the changing height of the water
column, associated with passing waves. These pressure time series can be converted to sea surface
elevations and wave frequency spectra. The shore stations store data continuously in digital memory.
Arrays of four pressure sensors placed in a 6m square configuration provide directional information
similar to that acquired by directional buoys. 

In addition to wave data, wind and temperature data are collected at some sites. Sea temperature is
measured either by buoys or by temperature gauges mounted to a pier. Anemometers are used to collect
wind data, which can be converted to average and maximum velocity. 

We have been fortunate to receive the cooperation of the US Coast Guard, local fishermen, and other
marine community entities for the deployment of these instruments. 

All the instruments at a particular site are connected to a shore station, either by cable, cellular phone or
radio link. They are interrogated automatically several times daily by a central computer at SIO. The
raw data from all of the instruments are archived on disk for access by CDIP clients. Analyzed data are
sent in near real-time to the National Weather Service computers to aid in marine weather advisories and
surf forecasts. Sun Microsystem's computers perform the analysis, archiving and dissemination of the
data. 

In addition, using numerical wave models and deep water wave measurements, CDIP is able to provide
near real-time Southern California swell predictions several times each day. These images are provided
for general oceanographic interest, depicting physical characteristics such as wave refraction and island
shadowing. For further queries, please refer to our FAQ. 

There is a real-time exhibit of CDIP data at SIO's Birch Aquarium. This display is intended to
complement their research and educational theme.