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The authors acknowledge the US National Science Foundation for support under award OCE 0957767, Project Title: EAGER: Exploratory Research in Non-FourierTidal Analysis of Hydrothermal Time Series, Principal Investigator: Dr. Adam Schultz, Oregon State University, College of Earth, Ocean and Atmospheric Sciences, 104 CEOAS Admin Bldg, Corvallis, OR 97331-5503, USA
Authors: nfTides is based on a method first explored as part of a PhD dissertation written by Dr. Tim Jupp (then at Cambridge University, now at Exeter University), under the supervision of Dr. Adam Schultz (then at Cambridge University, now at Oregon State University). Interested readers are encouraged to refer to: "Fluid Flow Processes at Mid-Ocean Ridge Hydrothermal Systems" by Timothy Edward Jupp, Pembroke College, Cambridge, submitted for the degree of Doctor of Philosophy on 30 September, 2000. We particularly draw the reader's attention to Chapter 3 of that work, "The analysis of tidal data", and specifically to Ch. 3.3.2 "The Admiralty Method".
The original source code was principally authored by Dr. Jupp, with the advice of Dr. Schultz, using original as well as library source code in the public domain. While several chapters of Jupp's thesis have been published in the scientific literature, regrettably this promising development in non-Fourier based parametric tidal analysis of hydrothermal signals has hitherto not been broadly promulgated. This approach was sufficiently promising, however, that NSF EAGER funding was sought to further realize the potential of this method, particularly for the type of relatively short and complicated time series that are typically collected from a variety of sensors deployed at seafloor hydrothermal system. Such short, complicated and typically noisy time series lend themselves very poorly to traditional Fourier-based spectral analysis for tidal constituents, and Jupp's work has demonstrated that many published interpretations of hydrothermal time series tidal components are biased, and in some cases, fundamentally flawed.
NSF EAGER support has allowed us to take a little known algorithm written in an archaic version of Fortran (a dialect of f77), and substantially modernize it. In common with the original approach, however we have included all required subroutines as source code, including some that are commonly found pre-installed as mathematical libraries on typical research computing systems. This is to enable to entire package to be installed on the target computer without need of searching for, and potentially installing, support libraries. As such, nfTides is intended to be a stand-alone package that will determine the principal solid earth and ocean diurnal and semidiurnal tidal components without need of installing any other package or library.
The current version of nfTides has been revised by Dr. Adam Schultz, under support of NSF OCE-095767.
We plan periodic updates of thesoftware, including the distribution of MATLAB and c++ versions of the source code. As the Admiralty Tide Tables are updated through annual editions printed by the UK Hydrographic Office, we will periodically update the table of Admiralty basis functions, which are provided for each day of the calendar year. Please check back to this site to see if the file "admiralty.in" has been updated. This will allow you to carry out non-Fourier tidal analysisfor time series collected more recently than the last date in the existing table of basis functions.