A TECHNIQUE FOR GRAPHIC PRESENTATION OF WATER LEVEL FORECASTS 

 USING A TOPOGRAPHIC CONTOUR CHART FORMAT 



Don Burns, Dennis Clark and Pat Martin 



Oceanographers 



U.S. Naval Oceanographic Office 



Washington, D. C. 20390 



ABSTRACT: A contoured graphic format has been adapted for the presentation 

 of water-level forecasts such that heights for any time can easily 

 be read from monthly charts for each station. An entire year's 

 forecast can be generated by an on-line plotter In 50 minutes. 

 The charts will be useful in day-to-day and long-range planning 

 of naval operations in tidal waters. 



INTRODUCTION 



During 1968, the Coastal Oceanography Branch, NAVOCEANO, provided 

 COMNAVFORV with limited water-level forecasts for Nha Be, RVN. The fore- 

 casts were presented in tabular form similar to standard "tide tables" and were 

 evaluated informally by the NAVOCEANO representative, NRDU-V (Naval 

 Research and Development Unit, Vietnam) (Figure 1, Coast and Geodetic Survey, 

 1969). The tabular format was especially difficult to use in conjunction with 

 other data such as moonrise and moonset for nighttime operational planning. 

 Based upon this in-field evaluation. It was decided to change the format, if 

 possible, from a tabular to a contoured display (Suthons, 1959). A graphic, 

 chart type format is considered to have an advantage over tabular listings because 

 a chart presents a complete picture of water-level fluctuations for an entire month 

 and can be rapidly interpreted by visual Inspection (O 'Conner, 1964). 



A prediction program (Pore and Cummings, 1967) Is now operational and 

 is run on a high-speed digital computer, including the contouring of the data 

 with an on-line plotter (Branstetter, 1966). Machine contouring insures that the 



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