The rate of change in the phase of a constituent, usually expressed in degrees per hour. The speed is equal to 360o divided by the constituent period expressed in hours
National Oceanic and Atmospheric Administration NOAA, Tide and Current Glossary, National Ocean Service, CO-OPS, Products and Services N/OPS3, Silver Spring, MD, USA 1999. http://co-ops.nos.noaa.gov/publications/glossary2. pdf, (ND/ Tide and Current - Amer) {830}