Abstract:
The Numerisation des Niveaux d'Eau (NUNIEAU) is an integrated and automated
MATLAB computer program tool kit for digitizing, transforming and validating
paper records of sea level variations, called marigrams, that can cut in half
the time required to digitize paper records.
This tool kit was developed in 2004 by F. Pons and is currently obtainable by
request from the developer, but will be
... available online on the IMPLI (Impact
des Evenements Extremes sur les Hydro-Systems du Littoral Mediterraneen
Francais) Web site in early 2006
Marigrams obtained from mechanical tide gauges provide the longest continuous
record of sea level variation (the longest sea level record along the French-
Mediterranean coast). With measurements of sea level obtained by satellite
observation and from automated tide gauges only available from the 1990's
onward, it is imperative to preserve information contained in the paper
records. Already, several marigrams have been lost.
The process of manually digitizing the marigrams is also a tedious task; about
25 hours of manual work are necessary to convert a year's worth of marigrams
into a numerical time series of sea level height at hourly timescales using a
digital pen. Eventual corrections of the numerical time series considerably
lengthen this work. The same task using NUNIEAU, with an off-the-shelf
personal computer (3-GHz CPU, 1Gb RAM), is reduced to approximately 12 hours,
including corrections of time and height shifts between consecutive weeks.
Summary from "EOS, Transactions, American Geophysical Union," 86:32. Sept. 20,
2005.